Information
-
Patent Grant
-
6366247
-
Patent Number
6,366,247
-
Date Filed
Monday, August 7, 200024 years ago
-
Date Issued
Tuesday, April 2, 200222 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
-
CPC
-
US Classifications
Field of Search
US
- 343 702
- 343 895
- 343 725
- 343 729
- 343 850
- 343 853
- 343 852
- 343 859
- 343 860
- 343 865
-
International Classifications
-
-
Disclaimer
Terminal disclaimer
Abstract
The present invention makes it possible to realize an antenna device and a portable radio set capable of greatly reducing the deterioration of antenna characteristics while used near a human body and greatly reducing the deterioration of communication quality by electrically connecting first and second antenna elements to a balanced-to-unbalanced transform circuit by connection means when a first antenna element is retracted, supplying power to the first and second antenna elements from an unbalanced transmission line through balanced-to-unbalanced transform means to operate the first and second antenna elements as antennas, preventing a leakage current from flowing to a ground member to which the unbalanced transmission line is grounded from the first and second antenna elements through the transmission in accordance with the balanced-to-unbalancecd transform by the balanced-to-unbalanced transform means, and thereby preventing the ground member from operating as an antenna.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an antenna device and a portable radio set, and more particularly, is suitably applied to a cellular telephone.
2. Description of the Related Art
The cellular telephone of this type has been decreased in size and weight so far in order to improve the portability. Thereby, a retract/pull-out type of whip antenna device is positively developed as an antenna device provided for a cellular telephone. There is a cellular telephone configured as shown in
FIGS. 1A and 1B
as the cellular telephone of the above type.
In case of a cellular telephone
1
having the above configuration, a whip antenna device
3
is providing for in a housing
2
made of a nonconductive material such as synthetic resin.
The antenna device
3
has an antenna section
6
provided with a rod antenna
4
made of a conductive wire rod and a helical antenna
5
formed by helically winding a conductive wire rod. The antenna section is set so as to be freely retracted and pulled out along a direction in which the antenna section
6
is pushed into the housing
2
shown by an arrow a at the upper end
2
A of the housing
2
(this direction is hereafter referred to as retracting direction) and inversely, along a direction in which the section
6
is pulled out of the housing
2
(this direction is hereafter referred to as pull-out direction).
In the antenna section
6
, a first power-supply member
7
made of a conductive material and having a protrusion
7
A is electrically and mechanically connected to the lower end of the rod antenna
4
and a joint
8
made of a nonconductive material is mechanically connected to the upper end of the rod antenna
4
.
Moreover, a second power-supply member
9
made of a conductive material is electrically and mechanically connected to the lower end of the helical antenna
5
and mechanically connected to the joint
8
. Thereby, in the antenna section
6
, the rod antenna
4
and the helical antenna
5
are mechanically connected each other by the joint
8
but they are electrically separated from each other.
Moreover, the rod antenna
4
is covered with a rod antenna cover
10
and the helical antenna
5
is stored in a cap-shaped helical antenna cover
11
so that the antennas
4
and
5
do not directly contact a user.
A circuit board (not illustrated) on which various circuit devices including a transceiving circuit
12
and a matching circuit
13
are mounted and a shielding case serving as a ground member made of a conductive material for covering the circuit board are stored in the housing
2
.
Moreover, an antenna power-supply terminal
14
made of a conductive material electrically connected to the matching circuit
13
is set inside of the upper end
2
A of the housing
2
and only either of the rod antenna
4
and helical antenna
5
is electrically connected to the antenna power-supply terminal
14
when the antenna section
6
is retracted or pulled out.
Actually, in the antenna device
3
, the antenna section
6
is pushed in and the helical antenna cover
11
is pushed in the retracting direction and made to contact the upper end
2
A of the housing
2
to push the rod antenna
4
into the housing
2
and store the rod antenna
4
in the housing
2
and electrically connect the second power-supply member
9
to the antenna power-supply terminal
14
.
Moreover in the antenna device
3
, power is supplied to the helical antenna
5
from the transceiving circuit
12
through the matching circuit
13
, antenna power-supply terminal
14
, and second power-supply member
9
in order under the above state to make the helical antenna
5
operate as an antenna.
Furthermore, in the antenna device
3
, by electrically separating the rod antenna
4
from the antenna power-supply terminal
14
by the joint
8
, the rod antenna
4
is not operated as an antenna.
In the antenna device
3
, however, when the second antenna cover
11
is pulled in the pull-out direction while the rod antenna
4
is stored in the housing
2
, the rod antenna
4
is pulled out to the outside from the upper end
2
A of the housing
2
, the protrusion
7
A of the first power-supply member
7
is made to contact the antenna power-supply terminal
14
, and thereby the first power-supply member
7
is electrically connected to the antenna power-supply terminal
14
.
Furthermore, in the antenna device
3
, power is supplied to the rod antenna
4
from the transceiving circuit
12
through the matching circuit
13
, antenna power-supply terminal
14
, and first power-supply member
7
in order under the above state to make the rod antenna
4
operate as an antenna.
Furthermore, in the antenna device
3
, by electrically separating the helical antenna
5
from the antenna power-supply terminal
14
by the joint
8
, the antenna
5
is not operated as an antenna.
In this connection, to make the rod antenna
4
and helical antenna
5
operate as antennas, the impedances of the rod antenna
4
and helical antenna
5
are matched with the impedance of the unbalanced transmission line
16
by the matching circuit
13
.
Moreover, the shielding case functions as ground for various circuit devices and moreover functions as an electrical shielding plate for preventing radio waves of external noise and radio waves emitted from the antenna section
6
from entering various circuit devices mounted on a circuit board.
Thereby, the cellular telephone
1
makes it possible to, at the time of pulling out the antenna section
6
, transmit a transmission signal configured of a high-frequency signal from the transceiving circuit
12
to the rod antenna
4
through the matching circuit
13
, transmit the transmission signal to a base station (not illustrated) through the rod antenna
4
, and transmit a reception signal configured of a high-frequency signal transmitted from the base station and received by the rod antenna
4
to the transceiving circuit
12
through the matching circuit
13
.
Moreover, the cellular telephone
1
makes it possible to prevent damage to the rod antenna
4
by storing the antenna
4
in the housing
2
at the time of retracting the antenna section
6
, transmitting a transmission signal from the transceiving circuit
12
to the helical antenna
5
through the matching circuit
13
under the above state, transmitting the transmission signal to a base station through the helical antenna
5
, and transmitting a reception signal transmitted from the base station and received by the helical antenna
5
to the transceiving circuit
12
through the matching circuit
13
.
The cellular telephone
1
having the above configuration is provided with an unbalanced transmission line
26
configured of a microstrip line formed on a circuit board, in which the rod antenna
4
or helical antenna
5
is electrically connected to the transceiving circuit
12
through the hot side of the unbalanced transmission line
26
and the matching circuit
13
sequentially, and the ground side of the unbalanced transmission line
26
is grounded to the shielding case.
Then, in the cellular telephone
1
, as shown in
FIGS. 2A and 2B
, when power is supplied to the rod antenna
4
and helical antenna
5
through the hot side of the unbalanced transmission line
26
to operate the rod antenna
4
and helical antenna
5
as antennas, a leakage current i
1
flows to the shielding case
27
having a potential almost equal to that of the ground side of the unbalanced transmission line
26
from the ground side and thereby, the shielding case
27
also operates as an antenna.
Therefore, in the cellular telephone
1
, when the shielding case
27
operates as an antenna and the housing
2
is held by a hand of a user or when the housing
2
is approached to the head of the user, antenna characteristics of the cellular telephone
1
are deteriorated because the shielding case
27
approaches a hand or the head of the user through the housing
2
.
When the antenna section
6
is pulled out, the physical length of the rod antenna
4
pulled out from the upper face
2
A of the housing
2
is comparatively large and it is possible to separate the rod antenna
4
from a hand of a user holding the housing
2
or the head of the user to which the housing
2
is approached. Therefore, deterioration of antenna characteristics of the cellular telephone
1
is almost caused by the shielding case
27
approached to a user.
However, when the antenna section
6
is retracted, the physical length of the helical antenna
5
protruded beyond the upper face
2
A of the housing
2
is very small as compared with the case of the pulled-out rod antenna
4
and the helical antenna
5
greatly approaches a hand of the user holding the housing
2
or the head of the user to which the housing
2
is approached together with the shielding case
27
. Therefore, antenna characteristics of the cellular telephone
1
are extremely deteriorated compared to the case in which the antenna s;section
6
is pulled out and as a result, a problem occurs that communication quality is deteriorated.
Moreover, the cellular telephone
1
has a problem that when the antenna section
6
is retracted, the shielding case
27
and helical antenna
5
are made to approach a hand or the head of a user and thereby, the power for unit time or unit mass absorbed in a specific portion of a user {so-called Specific Absorption Rate (SAR)) is increased.
SUMMARY OF THE INVENTION
In view of the foregoing, an object of the invention is to provide an antenna device and a portable radio set capable of greatly reducing the deterioration of communication quality when an antenna element is retracted.
The foregoing object and other objects of the invention have been achieved by the provision of an antenna device comprising a first antenna element provided so as to be freely retracted or pulled out, a second antenna element, an unbalanced transmission line for supplying power to the first and second antenna elements, balanced-to-unbalanced transform means for performing balanced-to-unbalanced transform between the unbalanced transmission line on one hand and the first and second antenna elements on the other, and connection means for electrically connecting the first and second antenna elements to the balanced-to-unbalanced transform circuit when the first antenna element is retracted and electrically connecting at least the first antenna element to the balanced-to-unbalanced transform circuit when the first antenna element is pulled out, in which power is supplied to the first and second antenna elements from the unbalanced transmission line through the balanced-to-unbalanced transform means so as to operate the first and second antenna elements as antennas when the first antenna element is retracted and power is supplied to at least the first antenna element from the unbalanced transmission line through the balanced-to-unbalanced transform means to operate the first antenna element as an antenna when the first antenna element is pulled out.
As a result, when the first antenna element is retracted, it is possible to prevent a leakage current from flowing through a ground member to which the unbalanced transmission line is grounded from the first or second antenna element through the unbalanced transmission line due to balanced-to-unbalanced transform by the balanced-to-unbalanced transform means, thereby preventing the ground member from operating as an antenna, and greatly reducing the deterioration of antenna characteristics near a human body.
Moreover, the present invention provides a portable radio set having an antenna device comprising a first antenna element provided so as to be freely retracted and pulled out, a second antenna element, an unbalanced transmission line for supplying power to the first and second antenna elements, balanced-to-unbalanced transform means for performing balanced-to-unbalanced transform between the unbalanced transmission line on one hand and the first and second antenna elements on the other, and connection means for electrically connecting the first and second antenna elements to the balanced-to-unbalanced transform circuit when the first antenna element is retracted and electrically connecting at least first antenna element to the balanced-to-unbalanced transform circuit when the first antenna element is pulled out, in which power is supplied to the first and second antenna elements from the unbalanced transmission line through the balanced-to-unbalanced transform means when the first antenna element is retracted to operate the first and second antenna elements as antennas and power is supplied to at least the first antenna element from the unbalanced transmission line through the balanced-to-unbalanced transform means when the first antenna element is pulled out to operate the first antenna element as an antenna.
As a result, when the first antenna element is retracted, it is possible to prevent a leakage current from flowing through a ground member to which the unbalanced transmission line is grounded from the first or second antenna element through the unbalanced transmission line due to balanced-to-unbalanced transform by the balanced-to-unbalanced transform means, and thereby, prevent the grounding member from operating as an antenna and greatly reduce the deterioration of antenna characteristics nearby a human body.
The nature, principle and utility of the invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings in which like parts are designated by like reference numerals or characters.
BRIEF DESCRIPTION OF THE DRAWINGS
In the accompanying drawings:
FIGS. 1A and 1B
are block diagrams showing the circuit configuration of a conventional cellular telephone;
FIGS. 2A and 2B
are schematic front views for explaining operations of a conventional shielding case serving as an antenna;
FIG. 3
is a schematic view showing the configuration of a balanced antenna;
FIGS. 4A and 4B
are schematic voltage-waveform diagrams for explaining operations of a balanced antenna;
FIG. 5
is a schematic diagram showing the configuration of an unbalanced antenna;
FIGS. 6A and 6B
are schematic voltage-waveform diagrams for explaining operations of an unbalanced antenna;
FIG. 7
is a schematic diagram showing the configuration of an intermediate-exciting-attitude antenna;
FIGS. 8A and 8B
are schematic voltage-waveform diagrams for explaining an operation of an intermediate-exciting-attitude antenna;
FIGS. 9A and 9B
are schematic sectional views for explaining the theory of a cellular telephone of the present invention;
FIG. 10
is a schematic perspective view showing the configuration of an unbalanced transmission line configured by a microstrip line;
FIG. 11
is a schematic block diagram for explaining the connection between an unbalanced transmission line on one hand and rod antenna and helical antenna on the other;
FIG. 12
is a schematic block diagram for explaining the connection between an unbalanced transmission line using a balun (Balanced-to-Unbalanced Transformer) on one hand and rod antenna and helical antenna on the other;
FIG. 13
is a block diagram showing the configuration of a balun;
FIG. 14
is a block diagram showing the configuration of a phase circuit of a balun;
FIGS. 15A and 15B
are schematic diagrams for explaining a shielding case when an antenna operates;
FIG. 16
is a block diagram for explaining the arrangement of a matching circuit at the unbalanced side of a balun;
FIG. 17
is a block diagram for explaining the arrangement of a matching circuit at the balanced side of a balun;
FIGS. 18A and 18B
are block diagrams showing the configuration of a matching circuit set to the balanced side of a balun;
FIG. 19
is a schematic side view showing a first embodiment of the configuration of a cellular telephone of the present invention;
FIG. 20
is a schematic diagram for explaining the arrangement of a rod antenna, a helical antenna, and a shielding case;
FIGS. 21A and 21B
are block diagrams showing the internal configuration of a cellular telephone of the first embodiment;
FIGS. 22A and 22B
are block diagrams showing the internal configuration of a second embodiment;
FIGS. 23A and 23B
are schematic sectional views showing the configuration of an antenna section of the second embodiment;
FIG. 24
is a schematic side view showing the configuration of a cellular telephone of a third embodiment;
FIGS. 25A and 25B
are block diagrams showing the internal configuration of a cellular telephone of the third embodiment;
FIGS. 26A and 26B
are block diagrams showing the internal configuration of a cellular telephone of a fourth embodiment;
FIG. 27
is a schematic sectional view showing the configuration of an antenna section of the fourth embodiment;
FIGS. 28A and 28B
are block diagrams showing the internal configuration of a cellular telephone of a fifth embodiment;
FIGS. 29A and 29B
are block diagrams showing the internal configuration of a cellular telephone of a sixth embodiment;
FIGS. 30A and 30B
are schematic sectional views showing the configuration of an antenna section of the sixth embodiment;
FIGS. 31A and 31B
are block diagrams showing the internal configuration of a cellular telephone of a seventh embodiment;
FIGS. 32A and 32B
are block diagrams showing the internal configuration of a cellular telephone of an eighth embodiment;
FIGS. 33A and 33B
are schematic sectional views showing the configuration of an antenna section of the eighth embodiment;
FIGS. 34A and 34B
are block diagrams showing the internal configuration of a cellular telephone of the ninth embodiment;
FIG. 35
is a schematic diagram showing the configuration of an unbalanced transmission line of another embodiment configured by a coaxial cable;
FIGS. 36A
to
36
C are block diagrams showing the configuration of a phase circuit of another embodiment;
FIG. 37
is a schematic diagram showing the configuration of a balun of another embodiment;
FIG. 38
is a schematic diagram showing the configuration of a balun of another embodiment;
FIGS. 39A and 39B
are schematic diagram showing the configuration of a balun of another embodiment;
FIG. 40
is a schematic diagram showing the configuration of a balun of another embodiment;
FIG. 41
is a top view showing a coil used for a transformer balun;
FIGS. 42A and 42B
are a schematic sectional view and a schematic diagram showing the configuration of a Sperrtopf balun of another embodiment using a coaxial cable;
FIG. 43
is a schematic diagram showing the configuration of a Sperrtopf balun of another embodiment using a microstrip line;
FIG. 44
is a schematic diagram showing the configuration of a balun of another embodiment;
FIGS. 45A and 45B
are schematic top views showing the configuration of antenna element of another embodiment substituted for first and second helical antennas;
FIGS. 46A
to
46
C are schematic top views showing the configuration of an antenna element of another embodiment;
FIG. 47
is a schematic diagram showing the configuration of an antenna element substituted for rod antenna;
FIGS. 48A and 48B
are schematic sectional views showing the configuration of an antenna section provided with a retractable rod antenna of another embodiment;
FIGS. 49A and 49B
are schematic sectional views showing the configuration of an antenna section of another embodiment provided with a retractable rod antenna;
FIGS. 50A and 50B
are schematic sectional views showing the configuration of an antenna section of another embodiment provided with a retractable rod antenna;
FIGS. 51A and 51B
are schematic side views for explaining push-in and pull-out directions of an antenna section of another embodiment; and
FIG. 52
is a block diagram for explaining the arrangement of matching circuits of another embodiment.
DETAILED DESCRIPTION OF THE EMBODIMENT
Preferred embodiments of this invention will be described with reference to the accompanying drawings:
(1) Theory
An antenna configured by first and second antenna elements
30
and
31
which are structurally and electrically symmetric like a dipole antenna as shown in
FIG. 3
is classified as a balanced antenna because the antenna has the same amplitude in the first and second antenna elements
30
and
31
as shown in
FIGS. 4A and 4B
and takes a balanced exciting attitude and operates when voltages with phases shifted from each other by an approximately 180° are generated.
Moreover, as shown in
FIG. 5
, like a monopole antenna almost vertically set to a ground member which can be regarded to be wider than a disk having a radius of one wavelength (electrical length) and to have an infinite size, a structure configured of a ground member
32
which can be regarded to be structurally asymmetric and have an infinite size and an antenna
33
set almost vertically to the member
32
takes an unbalanced exciting attitude because the vast ground member
32
becomes almost zero potential and a voltage changing at a predetermined cycle is generated in the antenna
33
and thereby, the antenna operates as shown in
FIGS. 6A and 6B
.
In this connection, because the unbalanced antenna has a vast ground member
32
, it is possible to easily estimate an image current flowing through the unbalanced antenna and select antenna characteristics of the unbalanced antenna almost similarly to a balanced antenna.
Moreover, as shown in
FIG. 7
, as the antenna of this type, an antenna is also used which is configured by structurally and electrically asymmetric first and second antenna elements
34
and
35
similarly to the case of the rod antenna
4
{FIGS.
1
A and
1
B}, helical antenna
5
{FIGS.
1
A and
1
B}, and a shielding case
27
{
FIGS. 2A
to
2
C} shown in the conventional cellular telephone
1
{FIGS.
1
A and
1
B}.
Because the antenna having the above configuration is structurally and electrically asymmetric, it takes an intermediate exciting attitude different from the balanced exciting attitude or unbalanced exciting attitude as shown in
FIGS. 8A and 8B
. Therefore, the antenna is classified as an antenna (hereafter referred to as intermediate-exciting-attitude antenna) different from a balanced antenna or unbalanced antenna.
Moreover,
FIG. 9
shows a cellular telephone
36
of the present invention excluding a matching circuit. In the cellular telephone
36
, a housing
37
is provided with a retract/pull-out type antenna device
40
having a rod antenna
38
and a helical antenna
39
serving as first and second antenna elements.
The rod antenna
38
and helical antenna
39
constitute an antenna (hereafter referred to as almost-balanced antenna) taking an almost-balanced exciting attitude, which is electrically symmetric because it is selected to almost the same electrical length though it is structurally asymmetric.
In this connection, in the present invention, an antenna provided for an antenna device is classified as an almost-balanced antenna by taking a balanced exciting attitude because it is electrically symmetric though it is structurally asymmetric unless otherwise specified.
FIG. 7A
shows the rod antenna
38
when retracted in which only the helical antenna
39
is protruded beyond the housing
37
, the rod antenna
38
in the housing
37
can be used as a transceiving antenna element together with the helical antenna
39
. And
FIG. 7B
shows the rod antenna
38
when pulled out in which only the rod antenna
38
can be used as a transceiving antenna element by protruding the rod antenna
38
beyond the housing
37
.
Actually, the antenna device
40
is provided with an unbalanced transmission line
42
configured of a microstrip line, the rod antenna
38
and helical antenna
39
are electrically connected to the transceiving circuit
41
through the unbalanced transmission line
42
or only the rod antenna
38
is electrically connected to the transceiving circuit
41
.
In this case,
FIG. 10
shows a microstrip line applied as the unbalanced transmission line
42
, which is configured by providing a strip conductor
44
for one face
43
A of a dielectric layer
43
having a predetermined thickness as a hot side and providing an earth conductor
45
for the other face
43
B of the dielectric layer
43
as a ground side and, for example, formed on a circuit board (not illustrated) stored in the housing
37
.
Moreover, in case of the antenna device
40
, as shown in
FIG. 11
, at the time of using the rod antenna
38
and helical antenna
39
together for transmission and reception, for example, the helical antenna
39
is basically electrically connected to the transceiving circuit
41
through the hot side
44
of the unbalanced transmission line
42
and the rod antenna
38
is electrically connected to the transceiving circuit
41
through the ground side
45
of the unbalanced transmission line
42
.
In case of the antenna device
40
, however, the rod antenna
38
and helical antenna
39
respectively take an almost-balanced exciting attitude while the unbalanced transmission line
42
takes an unbalanced exciting attitude because of grounding the ground side
45
, that is, the both antennas take exciting attitudes different from each other. Therefore, if the rod antenna
38
and helical antenna
39
are directly connected with the unbalanced transmission line
42
, current unbalance occurs due to the difference between the exciting attitudes when the rod antenna
38
and helical antenna
39
operate as antennas.
As a result, in the cellular telephone
36
, a leakage current i
2
flows to a shielding case having a potential almost equal to that of the ground side
45
of the unbalanced transmission line
42
from the rod antenna
38
through the ground side
45
and thereby, the shielding case is operated as an antenna by the leakage current i
2
. Thus, when the housing
37
is approached to a hand or the head of a user, antenna characteristics of the cellular telephone
36
are deteriorated.
Therefore, as shown in
FIG. 12
, in the case of the antenna device
40
of the present invention, a balun (balanced-to-unbalanced transformer)
46
for performing balanced-to-unbalanced transform is set between the unbalanced transmission line
42
on one hand and the rod antenna
38
and helical antenna
39
on the other.
As shown in
FIG. 13
, the balun
46
is configured by using two transmission lines such as first and second transmission lines
47
and
48
and setting a phase shifter
49
in the middle of the second transmission line
48
.
Moreover, in case of the balun
46
, one end of each of the first and second transmission lines
47
and
48
are electrically connected to the hot side
44
of the unbalanced transmission line
42
at the connection side (hereafter referred to as the unbalanced side) of the unbalanced transmission line
42
and the rod antenna
38
and helical antenna
39
are electrically connected to the other end of each of the first and second transmission lines
47
and
48
at the connection side (hereafter referred to as the balanced side) of an antenna element.
In this case, as shown in
FIG. 14
, the phase shifter
49
is configured by combining a plurality of symmetric-structure T-type phase circuits
50
obtained by connecting two inductive-reactance elements L
1
and L
2
in series, electrically connecting one end of a capacitive-reactance element C
1
to the connective midpoint P
1
between the elements L
1
and L
2
and grounding the other end of the capacitive-reactance element C
1
.
Furthermore, the balun
46
captures a high-frequency signal supplied from the transceiving circuit
41
through the hot side
44
of the unbalanced transmission line
42
from the unbalanced side, directly transmits the high-frequency signal to the balanced-side helical antenna
39
through the first transmission line
47
, shifts the phase of the high-frequency signal by approximately 180° from the helical antenna
39
in a frequency band used in a phase shifter
49
of the second transmission line
48
, and transmits the obtained phase-shifted high-frequency signal to the balanced-side rod antenna
38
.
Thereby, the balun
46
allows the rod antenna
38
and helical antenna
39
to generate a voltage attitude same as that in
FIGS. 4A and 4B
described above through balanced-to-unbalanced transform and to operate as almost-electrically-symmetric balanced antennas.
Thus, the balun
46
can prevent a current unbalance from occurring in the rod antenna
38
and helical antenna
39
and prevent the leakage current i
2
from flowing to the ground side
45
of the unbalanced transmission line
42
from the rod antenna
38
thereby preventing the shielding case from operating as an antenna.
In this connection, because the balun
46
can use a very-small chip of approximately 1 mm square for the phase shifter
49
as the inductive-reactance elements L
1
and L
2
and the capacitive-reactance element C of the phase circuit
50
. Therefore, it is possible to greatly downsize the balun
46
as a whole and thus, easily provide the balun
46
for the cellular telephone
36
which tends to be decreased in size and weight.
Moreover, in case of the antenna device
40
{FIGS.
9
A and
9
B}, when only the rod antenna
38
is used as a transceiving antenna element, only the rod antenna
38
is electrically connected to the balanced side of the balun
46
. Under the above state, when power is supplied to the rod antenna
38
from the transceiving circuit
41
through the unbalanced transmission line
42
and the balun
46
in order, the rod antenna
38
is operated as an antenna.
In this case, in the antenna device
40
, when only the rod antenna
38
is operated as an antenna as described above, balanced-to-unbalanced transform cannot be performed because there is not any antenna element to be electrically symmetric to the rod antenna
38
at the balanced side of the balun
46
. Thereby, the leakage current i
2
flows to the shielding case
51
from the ground side
45
of the unbalanced transmission line
42
similarly to the case of the conventional cellular telephone
1
{FIGS.
1
A and
1
B}.
Therefore, in case of the cellular telephone
36
of the present invention, the shielding case
51
also operates as an antenna in accordance with the leakage current i
2
at the time of making the rod antenna
38
protrude beyond the housing
37
and using only the rod antenna
38
as a transceiving antenna element as shown in
FIGS. 15A and 15B
.
In case of the rod antenna
38
of the cellular telephone
39
being retracted, however, at the time of making the helical antenna
39
protrude from the housing
37
and using the helical antenna
39
and the rod antenna
38
in the housing
37
as transceiving antenna elements, the helical antenna
39
and the rod antenna
38
are both operated as antennas but the shielding case
51
is prevented from operating as an antenna.
Thereby, the cellular telephone
39
makes it possible to greatly reduce the deterioration of antenna characteristics of the cellular telephone
36
nearby a human body and greatly reduce the deterioration of communication quality even if the housing
37
is held by a hand of a user or the housing
37
is approached to the head of the user because the shielding case
51
is not operated as an antenna.
Moreover, at the time of using the rod antenna
38
and helical antenna
39
as transceiving antenna elements, the cellular telephone
36
makes it possible to control power to be absorbed in a user and greatly lower the SAR by making the shielding case
51
function only as an original grounding and electrical shielding plate but not operate as an antenna.
In this connection,
FIGS. 9A and 9B
show the transceiving circuit
41
set outside of the shielding case
51
in the housing
37
in order to simplify the description. Actually, however, the transceiving circuit
41
is set inside of the shielding case
51
. Moreover, though the balun
46
is set outside of the shielding case
51
, it is also possible to set the balun
46
either inside or outside the shielding case
51
.
Moreover, in
FIGS. 9A and 9B
and
FIGS. 11
to
13
, a matching circuit is omitted in order to simplify explanation. However, as shown in
FIG. 16
, a matching circuit
52
can be set for example, between the unbalanced transmission line
42
and the balun
46
.
Moreover, as shown in
FIG. 17
, a matching circuit
53
can be set between balun
46
on one hand and the rod antenna
38
and the helical antenna
39
on the other. In this case, however, if the matching circuit
53
is grounded, a leakage current generated in the helical antenna
39
flows to the shielding case
51
through the matching circuit
53
even if the balun
46
performs balanced-to-unbalanced transform and as a result, the shielding case
51
operates as an antenna.
Therefore, as shown in
FIGS. 18A and 18B
by constituting the matching circuit
53
of a conductive-reactance element L
3
or capacitive-reactance element C
2
connected in parallel between the transmission lines
54
and
55
for electrically connecting the balanced side of the balun
46
with the rod antenna
38
and helical antenna
39
so as not to ground the matching circuit
53
, it is possible to set the matching circuit
53
between the balun
46
on one hand and the rod antenna
38
and helical antenna
39
on the other with no problem.
(2) First Embodiment
In
FIG. 19
, symbol
60
denotes a cellular telephone of first embodiment as a whole, which is configured by providing a whip antenna device
62
for a housing
61
made of a non-conductive material such as synthetic resin.
The housing
61
is formed like a box in which a loudspeaker
63
, a liquid-crystal portion
64
, various operation keys
65
, and a microphone
66
are arranged on the front
61
A.
In case of the antenna device
62
, an antenna section
69
having a rod antenna
67
and a helical antenna
68
serving as first and second antenna elements is set to the back
61
C of the upper face
61
B of the housing
61
in almost parallel with the longitudinal direction of the housing
61
(hereafter referred to as housing longitudinal direction) so as to be freely retracted and pulled out.
Moreover, the cellular telephone
60
is arranged so as to reduce the deterioration of antenna characteristics of the cellular telephone
60
nearby a human body because the rod antenna
67
and helical antenna
68
of an antenna section
69
can be separate from the head of a user even if the front
61
A of the housing
61
is approached to the head of the user because of setting the antenna section
69
to the back
61
C of the housing
61
.
Furthermore, as shown in
FIG. 20
the cellular telephone
60
is arranged so as to prevent a shielding case
70
from being capacity-coupled with the shielding case
70
and operating as an antenna at the time of operating the rod antenna
67
and helical antenna
68
as antennas by electrically separating the rod antenna
67
and helical antenna
68
of the antenna section
69
from the shielding case
70
stored in the housing
61
.
Actually,
FIGS. 21A and 21B
show an internal configuration of the cellular telephone
60
excluding a matching circuit and a shielding case, in which a circuit board (not illustrated) on which various circuit devices such as the transceiving circuit
41
and balun
46
are mounted is stored in the housing
61
and moreover, a shielding case made of a conductive material to cover the circuit board is stored in the housing
61
.
Moreover, the transceiving circuit
41
is electrically connected to the unbalanced side of the balun
46
through the unbalanced transmission line
42
configured of a microstrip line formed on the circuit board.
Furthermore, in the antenna device
62
, a rod-antenna bottom power-supply member
71
made of a conductive material is electrically and mechanically connected to the lower end of the rod antenna
67
, a rod-antenna top-power-supply member
72
made of a conductive material is electrically and mechanically connected to the upper end of the rod antenna
67
, and a joint
73
made of a nonconductive material is mechanically connected to the rod-antenna top-power-supply member
72
.
Furthermore, a helical-antenna power-supply member
74
made of a conductive material is electrically and mechanically connected to the lower end of the helical antenna
68
and the helical-antenna power-supply member
74
is mechanically connected to the joint
73
. Thereby, the helical antenna
68
and rod antenna
67
are mechanically connected to each other by the joint
73
but they are electrically separated from each other.
Furthermore, the rod antenna
67
is covered with a rod-antenna cover
75
made of a nonconductive material and the helical antenna
68
is stored in a helical-antenna cover
76
made of a nonconductive material and formed like a cap so as not to directly contact a user.
Moreover, in the antenna section
69
, top- and bottom-antenna power-supply terminals
77
and
78
respectively made of a conductive material and formed like a ring are electrically separately arranged inside of the upper face
61
B of the housing
61
and the rod antenna
67
is inserted into the top- and bottom-antenna power-supply terminals
77
and
78
respectively.
Furthermore, the top- and bottom-antenna power-supply terminals
77
and
78
are electrically connected to the balanced side of the balun
46
.
Thereby, in the antenna device
62
, when the antenna section
69
is retracted, the helical-antenna cover
76
is pushed in the retracting direction and made to contact with the upper face
61
B of the housing
61
to electrically connect the helical-antenna power-supply member
74
to the top-antenna power-supply terminal
77
and electrically connect the rod-antenna top-power-supply member
72
to the bottom-antenna power-supply terminal
78
.
Thus, in the antenna device
62
, the rod antenna
67
is stored in the housing
61
and the helical antenna
68
is protruded from the upper face
61
B of the housing
61
while the rod antenna
67
and helical antenna
68
are electrically connected to the balanced side of the balun
46
.
Moreover, in the antenna device
62
, when power is supplied to the rod antenna
67
and helical antenna
68
from the transceiving circuit
41
through the unbalanced transmission line
42
and balun
46
in order under the above state, the rod antenna
67
and helical antenna
67
are brought into the same voltage attitude as that described above for
FIGS. 4A and 4B
and operated as almost-balanced antennas.
Furthermore, in the antenna device
62
, a leakage current is prevented from flowing to the ground side of the unbalanced transmission line
42
from the rod antenna
67
in accordance with the balanced-to-unbalanced transform by the balun
46
, a shielding case is prevented from operating as an antenna because a leakage current resultantly flows to the shielding case from the ground side of the unbalanced transmission line
42
, and the shielding case is made to function only as original electrical shielding plate and ground.
Furthermore, in the antenna device
62
, when the antenna section
69
is pulled out, the helical-antenna cover
76
is pulled in the pull-out direction, thereby the rod-antenna bottom power-supply member
71
is electrically connected to the top-antenna power-supply terminal
77
and only the rod antenna
67
is electrically connected to the balanced side of the balun
46
to electrically separate the helical antenna
68
.
Thereby, in the antenna device
62
, when power is supplied to the rod antenna
67
from the transceiving circuit
41
through the unbalanced transmission line
42
and balun
46
in order under the above state, the rod antenna
67
is operated as an antenna.
Moreover, in the antenna device
62
, a leakage current flows to the shielding case from the ground side of the unbalanced transmission line
42
in the above case and thereby, the shielding case also operates as an antenna.
Thus, in the cellular telephone
60
, the portability is improved by pushing the rod antenna
67
into the housing
61
when actually retracting the antenna section
62
, a transmission signal is supplied to the rod antenna
67
and helical antenna
68
from the transceiving circuit
41
through the unbalanced transmission line
42
and balun
46
in order under the above state, the signal is transmitted to a base station through the rod antenna
67
and helical antenna
68
, and a reception signal transmitted from the base station and received by the rod antenna
67
and helical antenna
68
is supplied to the transceiving circuit
41
through the balun
46
and unbalanced transmission line
42
in order.
Moreover, in the cellular telephone
60
, when the antenna section
62
is pulled out, the antenna section
62
is easily pulled out by holding the helical-antenna cover
76
, a high-frequency transmission signal is supplied to the rod antenna
67
through the unbalanced transmission line
42
and balun
46
in order and transmitted to a base station (not illustrated) through the rod antenna
67
, and a high-frequency reception signal transmitted from the base station and received by the rod antenna
67
is supplied to the transceiving circuit
41
through the balun
46
and unbalanced transmission line
42
in order.
Then, in the cellular telephone
60
, when the antenna section
69
is pulled out, antenna characteristics near a human body deteriorate because the shielding case operates as an antenna. When the antenna section
69
is retracted, however, it is possible to greatly reduce the deterioration of antenna characteristics of the cellular telephone
60
near a human body even if the housing
61
is held by a hand of the user or brought near the head of the user by preventing the shielding case from operating as an antenna.
Moreover, in the cellular telephone
60
, it is possible to greatly reduce the power to be absorbed in a user, that is, the SAR by preventing the shielding case from operating as an antenna in the above case.
Furthermore, in the cellular telephone
60
, it is possible to secure a frequency band comparatively wider than that of the helical antenna
68
because the physical length of the helical antenna
68
is larger than that of the rod antenna
67
.
Furthermore, in the cellular telephone
60
, it is possible to always secure a comparatively-low frequency band by operating the rod antenna
67
as an antenna when the antenna section
69
is retracted and pulled out.
(3) Second Embodiment
FIGS. 22A and 22B
shown by providing the same symbols for portions corresponding to those in
FIGS. 21A and 21B
show a cellular telephone
80
of the second embodiment, which is similarly configured by the cellular telephone
60
{FIGS.
21
A and
21
B} of the above first embodiment except the configuration of an antenna section
82
of an antenna device
81
.
In
FIGS. 23A and 23B
shown by proving same symbols for portions corresponding to those in
FIGS. 21A and 21B
, the antenna section
82
is configured so that a rod-antenna bottom power-supply member
68
is electrically and mechanically connected to the lower end of a first antenna half-body
83
configured by a conductive cylindrical member, a pull-out stop section
84
is provided for the upper end of the first antenna half-body
83
, and a second antenna half-body
85
configured by a conductive rod member is inserted into a hole of the first antenna half-body
83
so as to be freely retracted and pulled out.
Moreover, a sliding spring
86
made of a conductive material is electrically and mechanically connected to the lower end of the second antenna half-body
85
located in the hole of the first antenna half-body
83
and a rod-antenna top power-supply member
72
is electrically and mechanically connected to the upper end of the second antenna half-body
85
.
Moreover, a helical-antenna power-supply member
74
is mechanically connected to the rod-antenna top power-supply member
72
through a joint
73
and thereby, the second antenna half-body
85
and the helical antenna
68
are mechanically connected by a joint
87
but they are electrically separated from each other.
Furthermore, the first and second antenna half-bodies
83
and
85
are covered with antenna covers
88
and
89
.
Thereby, in the antenna section
82
, when the second antenna half-body
85
is pushed into or pull out of the first antenna half-body
83
, the sliding spring
86
slides in the hole of the first antenna half-body
83
and a rod antenna
90
which can be extended and contracted by the first and second antenna half-bodies
83
and
85
is formed by electrically connecting the first antenna half-body
83
with the second antenna half-body
85
through the sliding spring
86
.
Actually in the antenna device
81
{FIGS.
22
A and
22
B}, when the antenna section
82
is retracted and the helical antenna cover
76
is pushed in the retracting direction, the antenna section
82
is pushed into the housing
61
while pushing the second antenna half-body
85
into the first antenna half-body
83
.
Then, in the antenna device
81
, when the helical antenna cover
76
is made to contact with the upper face
61
B of the housing
61
, the rod antenna
90
contracted by the first and second antenna half-bodies
83
and
85
is formed by pushing the second antenna half-body
85
into the first antenna half-body
83
and stored in the housing
61
.
Moreover, in this case, the antenna device
81
electrically connects the helical-antenna power-supply member
74
to the top-antenna power-supply terminal
77
and the rod-antenna top power-supply member
72
to the bottom-antenna power-supply terminal
78
and thus, electrically connects the helical antenna
68
and the contracted rod antenna
90
to the balanced of the balun
46
.
In this connection, in the antenna device
81
, when power is supplied to the helical antenna
68
and the contracted rod antenna
90
from the transceiving circuit
41
through the unbalanced transmission line
42
and balun.
46
in order under the above state, the helical antenna
68
and contracted rod antenna
90
are made to operate as almost-balanced antennas and in this case, a leakage current is prevented from flowing from the contracted rod antenna
90
to the ground side of the unbalanced transmission line
42
in accordance with the balanced-to-unbalanced transform by the balun
46
.
Moreover, in the antenna device
81
, when the antenna section
82
is pulled out and the helical-antenna cover
76
is pulled in the pull-out direction, the antenna section
82
is pulled to the outside from the upper face
61
B of the housing
61
while the second antenna half-body
85
is pulled out of the first antenna half-body
83
.
Furthermore, in the antenna device
81
, when the second antenna half-body
85
is fully pulled out of the first antenna half-body
83
and the rod antenna
90
extended by the first and second antenna half-bodies
83
and
85
is formed, the rod-antenna bottom power-supply member
71
is electrically connected to the top antenna power-supply terminal
77
. Thus, the extended rod antenna
90
is electrically connected to the balanced of the balun
46
and the helical antenna
68
is electrically separated from the balanced of the balun
46
.
Therefore, in the cellular telephone
80
, when the antenna section
82
is pushed in, the rod antenna
90
contracted by the first and second antenna half-bodies
83
and
85
is formed and pushed into the housing
61
. Thereby, a portion of the antenna section
82
to be pushed into the housing
61
can be greatly shortened compared to the case of the cellular telephone of the first embodiment {FIGS.
21
A and
21
B}.
Therefore, in the cellular telephone
80
, even when the antenna section
82
is not easily pushed into the housing
61
due to a space occupied by a battery or the like, it is possible to set the antenna section
82
to the upper face
61
B of the housing
61
so as to be freely retracted and pulled out.
Moreover, the cellular telephone
80
makes it possible to secure a comparatively-wide frequency band by operating the rod antenna
90
as an antenna at the time of retracting and pulling out the antenna section
82
.
(4) Third Embodiment
FIG. 24
shown by providing the same symbol for a portion corresponding to that of
FIG. 19
shows a cellular telephone
91
of the third embodiment which is configured similarly to the cellular telephone
60
(
FIG. 19
) of the above-described first embodiment except the configuration of an antenna section
93
of an antenna device
92
.
In this antenna section
93
, a helical antenna
68
is set in a helical antenna cover
94
set to the back-
61
C side of the upper face
61
B of a housing
61
and at rod antenna
67
is set to the upper face
94
A of the helical antenna cover
94
so as to be freely retracted and pulled out along the longitudinal direction of the housing.
Actually, in
FIGS. 25A and 25B
shown by providing the same symbol for a portion corresponding to that in
FIGS. 21A and 21B
, the lower end of the helical antenna
68
of the antenna section
93
is directly electrically connected to a top antenna power-supply terminal
77
.
Moreover, an antenna knob
95
made of a nonconductive material and having a T-shaped cross section is set to the upper end of the rod antenna
67
through a rod-antenna top power-supply member
72
.
Moreover, in the antenna device
92
, the rod antenna
67
is pushed in and pulled out along the axis of the helix of the helical antenna
68
.
Actually in the antenna device
92
, when the rod antenna
67
is retracted and the antenna knob
95
is pushed in the retracting direction and made to contact with the upper face
94
A of the helical antenna cover
94
, the antenna knob
95
is inserted into the helical antenna
68
and top antenna power-supply terminal
77
, and the rod-antenna top power-supply member
72
is electrically connected to the bottom antenna power-supply terminal
78
.
Thereby, in the antenna device
92
, the rod antenna
67
as well as the helical antenna
68
positioned at the side of the upper face
91
B of the housing
61
are electrically connected to the balanced of the balun
46
.
Moreover, in the antenna device
92
, when power is supplied to the helical antenna
68
and rod antenna
67
from a transceiving circuit
41
through an unbalanced transmission line
42
and the balun
46
in order under the above state, the helical antenna
68
and rod antenna
67
are operated as almost-unbalanced antennas and in this case, a leakage current is prevented from flowing from the rod antenna
67
to the ground side of the unbalanced transmission line
42
in accordance with the balanced-to-unbalanced transform by the balun
46
.
In this connection, in the antenna device
92
, when the rod antenna
67
is pulled out and the antenna knob
95
is pulled in the pull-out direction, a rod-antenna bottom power-supply member
71
is electrically connected to the top antenna power-supply terminal
77
, and a composite antenna is formed by the rod antenna
67
and helical antenna
68
and electrically connected to the balanced of the balun
46
.
Then, in the antenna device
92
, when power is supplied to the composite antenna from the transceiving circuit
41
through the unbalanced transmission line
412
and the balun
46
in order under the above state, the composite antenna is operated as an antenna.
Therefore, the cellular telephone
91
makes it possible to greatly reduce the deterioration of antenna characteristics of the cellular telephone
91
near a human body even if the housing
61
is held by a hand of a user or brought close to the head of the user and a shielding case is located near a human body by preventing the shielding case from operating as an antenna when the rod antenna
67
is retracted similarly to the case of the first embodiment described above. Moreover, it is possible to greatly reduce the power absorbed by a human body, that is, the SAR.
Moreover, the cellular telephone
91
makes it possible to always secure a comparatively-wide frequency band by operating the rod antenna
67
as an antenna when the rod antenna
67
is retracted and pulled out.
(5) Fourth Embodiment
FIGS. 26A and 26B
shown by providing the same symbol for a portion corresponding to that in
FIGS. 25A and 25B
show a cellular telephone
100
of the fourth embodiment, which is configured similarly to the cellular telephone
91
{FIGS.
25
A and
25
B} of the above-described third embodiment except the configuration of an antenna section
102
of an antenna device
101
.
In
FIGS. 27A and 27B
shown by providing the same symbol for a portion corresponding to that in
FIGS. 25A and 25B
and
FIGS. 23A
and
23
B, the antenna section
102
has a retractable rod antenna
103
in which a second antenna half-body
85
is inserted into a first antenna half-body
83
so as to be freely retracted and pulled out and a rod-antenna top power-supply member
72
is electrically and mechanically connected to the upper end of the second antenna half-body
85
.
Moreover, in the antenna device
101
, when the rod antenna
103
is pulled out and the antenna knob
95
is pulled in the pull-out direction, the rod antenna
103
is extended by pulling out the second antenna half-body
85
from the first antenna half-body
83
. When the second antenna half-body
85
is fully pulled out from the first antenna half-body
83
, a rod-antenna bottom power-supply member
71
is electrically connected to a top antenna power-supply terminal
77
to form a composite antenna by the helical antenna
68
and the extended rod antenna
103
.
Moreover, in the antenna device
101
, when the rod antenna
103
is pulled out and the antenna knob
95
is pulled in the pull-out direction, the rod antenna
103
is extended by pulling out the second antenna half-body
85
from the first antenna half-body
83
. When the second antenna half-body
85
is fully pulled out from the first antenna half-body
83
, a rod-antenna bottom power-supply member
71
is electrically connected to a top antenna power-supply terminal
77
to form a composite antenna by the helical antenna
68
and the extended rod an n
103
.
Thereby, in the cellular telephone
100
, when the rod antenna
103
is pushed in, it is possible to greatly shorten a portion of the rod antenna
103
to be pushed into the housing
61
by contracting the rod antenna
103
when the rod antenna
103
is pushed in compared to the case of the cellular telephone
91
of the above third embodiment.
Therefore, the cellular telephone
100
makes it possible to easily set the rod antenna
103
in the housing
61
even when it is not easy to push in the rod antenna
103
due to a space occupied by a battery or the like.
Moreover, the cellular telephone
91
makes it possible to always secure a comparatively-wide frequency band by operating the rod antenna
103
as an antenna when the rod antenna
103
is both retracted and pulled out.
(6) Fifth Embodiment
FIGS. 28A and 28B
shown by providing the same symbol for a portion corresponding to
FIGS. 25A and 25B
show a cellular telephone
105
of the fifth embodiment which is configured similarly to the cellular telephone
91
{FIGS.
25
A and
25
B} of the above-described third embodiment except the configuration of an antenna section
107
of an antenna device
106
.
In the antenna section
107
, a short-circuit member
108
made of a conductive material is electrically and mechanically connected to a predetermined portion along the longitudinal direction of a rod antenna
67
and the rod antenna
67
is covered with a rod antenna cover
109
made of a nonconductive material so as to expose the periphery of the short-circuit member
108
.
Moreover, an annular helical antenna short-circuit terminal
110
made of a conductive material is set inside of the upper face
94
A of a helical antenna cover
94
. Furthermore, the helical short-circuit terminal
110
is electrically and mechanically connected to the upper end of a helical antenna
68
.
In this case, in the antenna device
106
, when the rod antenna
67
is retracted and an antenna knob
95
is pushed in the retracting direction and made to contact with the upper face
94
A of the helical antenna cover
94
, the antenna knob
95
is inserted into the helical short-circuit terminal
110
, helical antenna
68
, and top antenna power-supply terminal
77
in order, to electrically connect a rod-antenna top power-supply member
72
to a bottom antenna power-supply terminal
78
.
Thereby, in the antenna device
106
, the rod antenna
67
is electrically connected to the balanced side of a balun
46
together with the helical antenna
68
set to the upper face
91
B of a housing
61
.
Then, in the antenna device
106
, when power is supplied to the helical antenna
68
and rod antenna
67
from a transceiving circuit
41
through an unbalanced transmission line
42
and the balun
46
in order under the above state, the helical antenna
68
and rod antenna
67
are operated as almost-balanced antennas and in this case, a leakage current is prevented from flowing from the rod antenna
67
to the ground side of the unbalanced transmission line
42
in accordance with the balanced-to-unbalanced transform by the balun
46
.
In this connection, in the antenna device
106
, when the rod antenna
67
is pulled out and the antenna knob
95
is pulled in the pull-out direction, a rod-antenna bottom power-supply member
71
is electrically connected to the bottom antenna power-supply terminal
78
and the short-circuit member
108
is electrically connected to the helical short-circuit terminal
110
. Thus, the upper and lower ends of the helical antenna
68
are short-circuited with the rod antenna
67
to from a composite antenna.
In this case, in the antenna device
106
, when power is supplied to the composite antenna from the transceiving circuit
41
through the unbalanced transmission line
42
and balun
46
in order, the helical antenna
68
of the composite antenna does not operate as an antenna because of the short circuit with the rod antenna
67
so that only the rod antenna
67
is operated as an antenna.
Therefore, the cellular telephone
106
makes it possible to greatly reduce the deterioration of antenna characteristics of the cellular telephone
91
near a human body even if the housing
61
is held by a hand of a user or the housing
61
is brought close to the head of the user and a shielding case is located near a human body because the shielding case is not operated as an antenna when the rod antenna
67
is retracted, similarly to the case of the above-described third embodiment. Moreover, it is possible to greatly reduce the SAR by controlling the power to be absorbed by a human body from the shielding case.
Moreover, the cellular telephone
91
makes it possible to always secure a comparatively-wide frequency band by operating the rod antenna
68
as an antenna when the rod antenna
67
is retracted and pulled out.
(7) Sixth Embodiment
FIGS. 29A and 29B
shown by providing the same symbol for a portion corresponding to that in
FIGS. 28A and 28B
show a cellular telephone
112
of the sixth embodiment, which is configured similarly to the cellular telephone
105
{FIGS.
28
A and
28
B} of the fifth embodiment except the configuration of an antenna section
114
of an antenna device
113
.
In this case, in
FIGS. 30A and 30B
shown by providing the same symbol for a portion corresponding to that in
FIGS. 28A and 28B
and
FIGS. 27A and 27B
, the antenna section
114
has a retractable rod antenna
115
in which a second antenna half-body
85
is inserted into a first antenna half-body
83
so as to be freely retracted and pulled out, a short-circuit member
116
is electrically and mechanically connected to a predetermined portion of the first antenna half-body
83
, and the first antenna half-body
83
is covered with a rod antenna cover
117
made of a nonconductive material so as to expose the periphery of the short-circuit member
116
.
Then, in the antenna device
113
{FIGS.
29
A and
29
B}, when the rod antenna
115
is retracted and an antenna knob
95
is pushed in the retracting direction and made to contact with the upper face
94
A of a helical antenna cover
94
, the rod antenna
115
is contracted by pushing the second antenna half-body
85
into the first antenna half-body
83
, the contracted rod antenna
115
is stored in the housing
61
, and a rod-antenna top power-supply member
72
is electrically connected to a bottom antenna power-supply terminal
78
.
Moreover, in the antenna device
113
, when the rod antenna
115
is pulled out and the antenna knob
95
is pulled in the pull-out direction, the second antenna half-body
85
is pulled out of the first antenna half-body
83
to extend the rod antenna
115
. In this case, the rod-antenna bottom power-supply member
71
is electrically connected to the top antenna power-supply terminal
77
and the short-circuit member
116
is electrically connected to the helical short-circuit terminal
116
. Thus, upper and lower ends of the helical antenna
68
are short-circuited with the extended rod antenna
115
to form a composite antenna.
Thus, the cellular telephone
112
makes it possible to greatly shorten a portion of the rod antenna
115
to be pushed into the housing
61
compared to the case of the cellular telephone of the fifth embodiment by contracting the rod antenna
115
and pushing the antenna
115
into the housing
61
when the rod antenna
115
is pushed in.
Therefore, the cellular telephone
112
makes it possible to easily set the rod antenna
115
in the housing
61
so as to be freely retracted and pulled out even when it is difficult to easily push in the rod antenna
115
due to a space occupied by a battery or the like.
Moreover, the cellular telephone
112
makes it possible to always secure a comparatively-wide frequency band by operating the rod antenna
115
as an antenna at the time of both pushing in and pulling out the rod antenna
115
.
(8) Seventh Embodiment
FIGS. 31A and 31B
shown by providing the same symbol for a portion corresponding to
FIGS. 25A and 25B
show a cellular telephone
119
of the seventh embodiment, which is configured similarly to the cellular telephone
91
{FIGS.
25
A and
25
B} except the configuration of an antenna section
121
of an antenna device
120
.
In the antenna section
121
, a joint
122
made of a nonconductive material is mechanically connected to a rod-antenna top power-supply member
72
of at rod antenna
67
, an antenna member
123
made of a conductive material is mechanically connected to the joint
122
, and moreover an antenna knob
124
made of a nonconductive material is mechanically connected to the antenna member
123
. Thereby, the rod antenna
67
and antenna member
123
are mechanically connected each other by the joint
122
but they are electrically separated from each other.
Moreover, an annular helical-antenna power-supply member
125
made of a conductive material is electrically and mechanically connected to the lower end of the helical antenna
68
.
Moreover, in the antenna device
120
, an annular top-antenna power-supply terminal
126
made of a conductive material is set inside of the upper face
61
B of the housing
61
and electrically connected to the balanced of a balun
26
.
Furthermore, in the antenna device
120
, the rod antenna
67
is inserted into the helical antenna
68
, helical-antenna power-supply member
125
, and top antenna power-supply terminal
126
so as to be pushed in and pulled out.
Actually in the antenna device
120
, when the rod antenna
67
is retracted and the antenna knob
124
is pushed in the retracting direction and made to contact with the upper face
94
A of the helical antenna cover
94
, the antenna member
123
is electrically connected to the helical-antenna power-supply member
125
and top antenna power-supply terminal
126
and the rod-antenna top power-supply member
72
is electrically connected to the bottom antenna power-supply terminal
78
.
Thereby, in the antenna device
120
, the antenna member
123
is electrically connected to the helical antenna
68
to form a composite antenna and the rod antenna
67
is electrically connected to the balanced of the balun
46
together with the composite antenna.
Moreover, in the antenna device
120
, when power is supplied to the composite antenna and the rod antenna
67
from a transceiving circuit
41
through an unbalanced transmission line
42
and the balun
46
in order under the above state, the composite antenna and the rod antenna
67
are operated as almost-balanced antennas and in this case, a leakage current is prevented from flowing to the ground side of the unbalanced transmission line
42
from the rod antenna
67
in accordance with the balanced-to-unbalanced transform by the balun
46
, and thus a shielding case is prevented from operating as an antenna.
Moreover, in the antenna device
120
, when the rod antenna
67
is pulled out and the antenna knob
124
is pulled in the pull-out direction, the rod-antenna bottom power-supply member
71
is electrically connected to the top antenna power-supply terminal
126
and thus, only the rod antenna
67
is electrically connected to the balanced of the balun
46
.
Thereby, in the antenna device
120
, when power is supplied to the helical antenna
68
from the transceiving circuit
41
through the unbalanced transmission line
42
and balun
46
in order, the helical antenna
68
is operated as an antenna.
Thus, the cellular telephone
119
makes a shielding case function as only an original electrical shielding plate and ground without operating as an antenna when the rod antenna
67
is retracted and thereby, makes it possible to greatly reduce the deterioration of antenna characteristics of the cellular telephone
119
nearby a human body and moreover, greatly decrease the SAR by controlling the power to be absorbed in a human body from the shielding case.
Moreover, the cellular telephone
119
makes it possible to secure a comparatively-wide frequency band by operating the rod antenna
67
as an antenna when the rod antenna
67
is both retracted and pulled out.
(9) Eighth Embodiment
FIGS. 32A and 32B
shown by providing the same symbol for a portion corresponding to that in
FIGS. 31A and 31B
show a cellular telephone
127
of the eighth embodiment, which is configured similarly to the cellular telephone
119
{FIGS.
31
A and
31
B} of the seventh embodiment except the configuration of an antenna section
129
of an antenna device
128
.
In
FIGS. 33A and 33B
shown by providing the same symbol for a portion corresponding to that in
FIGS. 31A and 31B
, and
FIGS. 27A and 27B
, the antenna section
129
is provided with a retractable rod antenna
130
in which a second antenna half-body
85
is inserted into a first antenna half-body
83
so as to be freely retracted and pulled out.
Moreover, in the antenna device
128
{FIGS.
32
A and
32
B}, when the rod antenna
130
is retracted and an antenna knob
124
is pushed in the retracted direction and made to contact with the upper face
94
A of a helical antenna cover
94
, the rod antenna
130
is contracted by pushing the second antenna half-body
85
into the first antenna half-body
83
, the contracted rod antenna
130
is stored in the housing
61
, and in this case, the antenna member
123
is electrically connected to the helical-antenna power-supply member
125
and top antenna power-supply terminal
126
and a rod-antenna top power-supply member
72
is electrically connected to a bottom antenna power-supply terminal
78
.
Thereby, in the antenna device
128
, the antenna member
123
is electrically connected to the helical antenna
68
to form a composite antenna and the rod antenna
67
is electrically connected to the balanced of a balun
46
together with the composite antenna.
Moreover, in the antenna device
128
, when the rod antenna
130
is pulled out and the antenna knob
124
is pulled in the pull-out direction, the second antenna half-body
85
is pulled out of the first antenna half-body
83
to extend the rod antenna
130
and in this case, the rod-antenna bottom power-supply member
71
is electrically connected to the top antenna power-supply terminal
126
.
Thereby, in the cellular telephone
127
, it is possible to greatly shorten a portion of the rod antenna
130
to be pushed into the housing
61
compared to the case of the cellular telephone
119
of the seventh embodiment by contracting the rod antenna
130
when the rod antenna
130
is pushed in.
Therefore, in the cellular telephone
127
, it is possible to easily set the rod antenna
130
in the housing
61
so as to be freely retracted and pulled out even when the rod antenna
130
is not easily pushed in due to a space occupied by a battery or the like.
Moreover, the cellular telephone
127
makes it possible to secure a comparatively-wide frequency band by operating the rod antenna
130
as an antenna when the rod antenna
130
is both retracted and pulled out.
(10) Ninth Embodiment
FIGS. 34A and 34B
shown by providing the same symbol for a portion corresponding to that in
FIGS. 28A and 28B
show a cellular telephone
131
of the ninth embodiment, which is configured similarly to the cellular telephone
105
{FIGS.
28
A and
28
B} of the above-described fifth embodiment except the configuration of an antenna section
133
of an antenna device
132
.
In the antenna section
133
, a helical antenna cover
134
is provided for the back
61
C of the upper face
61
A of a housing
61
and a helical short-circuit terminal
135
made of a conductive material and a top antenna power-supply terminal
136
made of a conductive material are set to the upper face
134
A and lower face
134
B of the helical antenna cover
134
so as to hold a predetermined lateral face (hereafter referred to as antenna sliding face)
134
C.
Moreover, a helical antenna
68
is set in the helical antenna cover
134
so that the axis of the helix of the antenna
68
is almost parallel with the longitudinal direction of the housing, the upper end of the helical antenna
68
is electrically connected to the helical short-circuit terminal
135
, and the lower end of the helical antenna
68
is electrically connected to the top antenna power-supply terminal
136
. In this connection, the top antenna power-supply terminal
136
is also electrically connected to the balanced of the balun
46
.
Moreover, in the antenna device
132
, the rod antenna
67
is set to the upper face
61
A of the housing
61
so that the longitudinal direction of the antenna
67
is almost parallel with the axis of the helix of the helical antenna
68
and slides on the antenna sliding face
134
C of the helical antenna cover
134
so that the antenna
67
is pushed in or pulled out.
Moreover, an antenna knob
137
made of a nonconductive material and having an L-shaped cross section is provided for the rod-antenna top power-supply terminal
72
at the upper end of the rod antenna
67
.
Thereby, in the antenna device
132
, when the rod antenna
67
is retracted and the antenna knob
137
is pushed in the retracting direction and made to contact with the upper face
61
A of the housing
61
, the rod-antenna top power-supply member
72
is electrically connected to the bottom antenna power-supply terminal
78
, and thus the rod antenna
67
is electrically connected to the balanced of the balun
46
together with the helical antenna
68
.
Then, in the antenna device
132
, when power is supplied to the helical antenna
68
and rod antenna
67
from a transceiving circuit
41
through an unbalanced transmission line
42
and the balun
46
in order under the above state, the helical antenna
68
and rod antenna
67
are operated as almost-balanced antennas and in this case, a leakage current is prevented from flowing to the ground side of the unbalanced transmission line
42
from the rod antenna
67
in accordance with the balanced-to-unbalanced transform by the balun
46
and thus, a shielding case is prevented from operating as an antenna.
In this connection, in the antenna device
132
, when the rod antenna
67
is pulled out and the antenna knob
136
is pulled in the pull-out direction, a short-circuit member
108
is electrically connected to the helical short-circuit terminal
135
, the rod-antenna bottom power-supply member
71
is electrically connected to the top antenna power-supply terminal
78
, and thus upper and lower ends of the helical antenna
68
are short-circuited with the rod antenna
67
to form a composite antenna.
Then, in the antenna device
132
, when power is supplied to the composite antenna from the transceiving circuit
41
through the unbalanced transmission line
42
and balun
46
in order under the above state, the helical antenna
68
of the composite antenna does not operate as an antenna because of the short-circuit with the rod antenna
67
so that only the rod antenna
67
is operated as an antenna.
Thereby, the cellular telephone
131
makes it possible to greatly reduce the deterioration of antenna characteristics of the cellular telephone nearby a human body and the power to be absorbed in a human body, that is, the SAR by making a shielding case function only as the original electric shielding plate and ground without operating the shielding case as an antenna when the rod antenna
67
is retracted, similarly to the case of the above-described fifth embodiment.
Moreover, the cellular telephone
131
makes it possible to secure a comparatively-wide frequency band by operating the rod antenna
67
as an antenna when the rod antenna
67
is both retracted and pulled out.
Furthermore, the cellular telephone
131
makes it possible to easily constitute the antenna device
132
without performing complex alignment for inserting the rod antenna
67
into the helical antenna
68
because of setting the axis of the helix of the helical antenna
68
almost in parallel with the longitudinal direction of the rod antenna
67
.
(11) Other Embodiment
For the above embodiments 1 to 9, a case is described in which the microstrip line
34
shown in
FIG. 10
is used as the unbalanced transmission line
42
. However, the present invention is not restricted to the above case. It is also possible to apply various unbalanced transmission lines including a coaxial cable
142
formed by insulating a cylindrical external conductor
140
(that is, ground side) from a central conductor
141
(that is, hot side) inserted into the external conductor
140
shown in
FIG. 35
to the present invention.
Moreover, for the above embodiments 1 to 9, a case is described in which the phase shifter
49
configured by combining the phase circuits
50
shown in
FIG. 14
with the balun
46
shown in
FIG. 13
is used. However, the present invention is not restricted to the above case. It is possible to use one of phase shifters having various configurations such as a phase shifter configured by combining a plurality of symmetric-structural T-type phase circuits
144
respectively obtained by connecting two capacitive reactance elements C
3
and C
4
in series and electrically connecting one end of an inductive reactance element L
4
to the connection midpoint P
2
between the elements C
3
and C
4
, a phase shifter configured by combining a plurality of symmetric-structural π-type phase circuits
145
respectively obtained by electrically connecting one end of capacitive reactance elements C
5
and C
6
to both ends of an inductive reactance element L
5
and grounding the other ends of the capacitive reactance elements C
5
and C
6
, and a phase shifter configured by combining a plurality of symmetric-structural π-type phase circuits
146
obtained by electrically connecting one end of inductive reactance elements L
6
and L
7
to both ends of a capacitive reactance element C
7
and grounding the other ends of the inductive reactance elements L
6
and L
7
as long as they can shift a phase of a high-frequency signal up to approximately 180° in a frequency band used.
Furthermore, for the above embodiments 1 to 9, a case is described in which the balun
46
shown in
FIG. 13
is used. However, the present invention is not restricted to the above case. It is also possible to use one of baluns having various configurations as long as they can prevent a leakage current from flowing to the ground side of the unbalanced transmission line
42
from an almost-balanced antenna.
Actually, as one of the baluns of these types,
FIG. 37
shows a balun
148
of another configuration using an unbalanced transmission line
147
configured of a coaxial cable, which is configured by electrically connecting one end of the hot side
151
of a coaxial cable (hereafter referred to as bypass line)
150
having an electrical length of ½ wavelength to one end of the hot side of the unbalanced transmission line
147
at a frequency used and moreover, electrically connecting one end of the ground side
153
of the bypass line
150
to one end of the ground side
152
of the unbalanced transmission line
147
. That is, the balun
148
of this configuration uses the bypass line
150
having an electrical length of ½ wavelength instead of the phase shifter
49
of the balun
46
in FIG.
13
.
In the balun
148
of the above configuration, a first antenna element of an almost-balanced antenna is electrically connected to one end of the hot side
149
of the unbalanced transmission line
147
and a second antenna element of an almost-unbalanced antenna is electrically connected to the other end of the hot side
151
of the bypass line
150
, and a high-frequency signal to be transmitted to the first antenna element through the hot side
149
of the unbalanced transmission line
147
is also transmitted to the second antenna element by shifting the phase of the signal to the first antenna element by approximately 180° through the hot side
151
of the bypass line
150
, and thereby a leakage current is prevented from flowing to the ground side
152
of the unbalanced transmission line
147
from the second antenna element.
Moreover, as one of these types of baluns, as shown in
FIG. 38
, there is a balun referred to as so-called LC-bridge balun which is configured by alternately and annularly connecting first and second inductive reactance elements L
8
and L
6
with first and second capacitive reactance elements C
8
and C
9
in order, electrically connecting the hot side of a not-illustrated unbalanced transmission line to the connection midpoint P
3
between the first inductive reactance element L
8
and the second capacitive reactance element C
9
, electrically connecting the ground side of the unbalanced transmission line to the connection midpoint P
4
between the first capacitive reactance element C
8
and the second inductive reactance element L
6
, electrically connecting the first antenna element of a not-illustrated almost-balanced antenna to the connection midpoint P
5
between the first inductive reactance element L
8
and the first capacitive reactance element C
8
, and electrically connecting the second antenna element of the almost-balanced antenna to the connection midpoint P
6
between the second inductive reactance element L
8
and the second capacitive reactance element C
8
.
In the balun
155
of the above configuration, by equalizing the inductances L of the first and second inductive reactance elements L
8
and L
6
and the capacitances C of the first and second capacitive reactance elements C
7
and C
8
, and selecting the inductance L and capacitance C so that the inductance L and capacitance C meet the following expressions (1) and (2), a high-frequency signal supplied from the hot side of an unbalanced transmission line is directly transmitted to the first antenna element from the connection midpoint PS, the phase of the high-frequency signal is shifted by approximately 180° from the first antenna element in a frequency band used, and an obtained phase-shifted high-frequency signal is transmitted to the second antenna element from the connection midpoint P
6
. In the above expressions, Z
1
denotes the impedance between the hot side and ground side of an unbalanced transmission line and Z
2
denotes the impedance between the midpoints P
5
and P
6
. Moreover, f denotes a frequency used.
(2πf)
2
LC=1 (1)
Then, the balun
155
having the above configuration can be formed as a microchip of approximately 1 mm square similarly to the case of the phase shifter
49
of the above-described balun
46
shown in FIG.
13
. Therefore, it is possible to easily set the balun
155
to a cellular telephone tending to decrease in size and weight.
Moreover, as shown in
FIGS. 39A and 39B
, the balun of this type includes a transformer balun
158
configured by making an air-core coil
157
formed between hot and ground sides and ground side of a not-illustrated unbalanced transmission line face an air-core coil
157
formed between first and second antenna elements of an almost-balanced antenna and a transformer balun
161
configured by making an air-core coil
159
formed between the hot side of an unbalanced transmission line and the first antenna element of an almost-balanced antenna face an air-core coil
160
formed between the ground side of the unbalanced transmission line and the second antenna element of the almost-balanced antenna.
Moreover, as shown in
FIG. 40
, the balun of the above type includes a transformer balun
166
configured by making an air-core coil
162
formed between the hot side of a not-illustrated unbalanced transmission line and the first antenna element of an almost-balanced antenna face an air-core coil
163
formed between the ground side and the ground of the unbalanced transmission line and making an air-core coil
1634
formed between the ground side of the unbalanced transmission line and the second antenna element of the almost-balanced antenna face an air-core coil
165
formed between the hot side and the ground of the unbalanced transmission line.
In this connection, in the transformer balun
166
having the above configuration, the impedance between connection terminals of the first and second antenna elements is approximately four times (
4
Z
3
) larger than the impedance between the hot and ground sides of the unbalanced transmission line.
Moreover, in the case of the transformer baluns
158
,
161
, and
166
shown in
FIGS. 39A and 39B
and
FIG. 40
, it is possible to use a pair of coils
170
and
171
formed of a through-hole
168
and a conductor pattern
169
for a multilayer wiring board
167
instead of the air-core coils
156
,
157
,
159
,
160
,
162
,
163
,
164
, and
165
as shown in FIG.
41
.
Moreover, by using a coil formed by integrating a conductor pattern, the transformer baluns
158
,
161
, and
166
can be respectively formed of a microchip of approximately 1 to 3 mm square. Therefore, it is possible to easily set the microchip even when an arrangement space is limited similarly to the case of the above-described LC bridge balun
155
(FIG.
38
).
Furthermore, as one of the baluns of the above type,
FIGS. 42A and 42B
show a balun
173
of another configuration using the unbalanced transmission line L
47
configured of a coaxial cable, which is referred to as the so-called Sperrtopf balun or Bazooka balun in which the unbalanced transmission line
147
is inserted into a cylindrical conductor
174
, one end
174
A of the cylindrical conductor
174
is opened, and the other end
174
B of it is short-circuited with the ground side
152
of the unbalanced transmission line
147
.
In the balun
173
having the above configuration, the first antenna element of the almost-balanced antenna is electrically connected to the hot side
149
of the unbalanced transmission line
147
at the open side (balanced side) of the cylindrical conductor
174
, the second antenna element of the almost-balanced antenna is electrically connected to the ground side
152
of the unbalanced transmission line
147
, and the transceiving circuit
41
is electrically connected to the hot side
149
and ground side
152
of the unbalanced transmission line
147
at the short-circuited side (unbalanced side) of the cylindrical conductor
174
.
Moreover, in the balun
173
, the unbalanced transmission line
147
can be regarded as a transmission line having an electrical length of ¼ wavelength in which as a whole, the line
147
serves as an internal conductor, the cylindrical conductor
174
serves as an external conductor, and either of them is contracted at the time of viewing the unbalanced side from the balanced side because the frequency used by the cylindrical conductor
174
is selected as an electrical length of ¼ wavelength and the impedance becomes infinite to a leakage current. Therefore, it is possible to prevent a leakage current from flowing to the ground side
152
of the unbalanced transmission line
147
.
In this connection,
FIG. 43
shows a Sperrtopf balun
175
using the unbalanced transmission line
42
configured of a microstrip line, which becomes equivalent to the Sperrtopf balun
173
shown in
FIGS. 42A and 42B
and operates similarly to the balun
173
by assuming the hot side
44
as the central conductor of a coaxial cable and thereby forming it into a line and forming the ground side
45
into a shape like the cross section of external conductor and cylindrical conductor of the coaxial cable.
Moreover, as the balun of the above type,
FIG. 44
shows a balun
176
of another configuration using the unbalanced transmission line
147
configured of a coaxial cable, which is configured by arranging the unbalanced transmission line
147
and a conductor (hereafter referred to as branch conductor)
177
having an electrical length of ¼ wavelength while putting the other ends of the line
147
and the conductor in order and electrically connecting one end of the branch conductor
177
to the hot side
149
of the unbalanced transmission line
147
and the other end of the conductor
177
to a portion facing the ground side
152
of the unbalanced transmission line
147
.
In case of the balun
176
having the above configuration, a first antenna element is electrically connected to the other end of the hot side
149
of the unbalanced transmission line
147
and a second antenna element is electrically connected to the other end of the ground side
152
of the unbalanced transmission line
147
. Thereby, the balun
176
serves as a circuit equivalent to the baluns
173
and
175
shown in
FIGS. 42A and 42B
and FIG.
43
and prevents a leakage current by making the impedance of the other end of the hot side
149
of the unbalanced transmission line
147
infinite similarly to the case of the baluns
173
and
175
.
Moreover, for the above-described embodiments 1 to 9, a case is described in which the helical antenna
68
formed by helically winding a conductive wire is used. However, the present invention is not restricted to the above case. As shown in
FIGS. 45A and 45B
, it is permitted to use one of various antenna elements including a helical antenna
181
obtained by forming a through-hole
179
and a conductor pattern
180
on a multilayer wiring board
178
and an antenna element
184
configured by meanderingly forming a conductor pattern
183
on one face
182
A of a circuit board
182
.
Moreover, as shown in
FIGS. 46A
to
46
C, instead of the helical antenna it is possible to use a thin antenna element such as an antenna element
185
obtained by linearly forming a conductive thin plate, an antenna element
186
meanderingly formed of a conductive thin plate, or an antenna element
187
formed of a conductive thin plate into a quadrangle for the inside or outside of the housing
61
. By using the above antenna element, it is possible to prevent the housing
61
from increasing in size.
Furthermore, for the above first, third, fifth, seventh, and ninth embodiments, a case is described in which the rod antenna
67
made of a conductive rod wire is used. However, the present invention is not restricted to the above case. As shown in
FIG. 47
, it is possible to use one of various antenna elements such as a densely-wound coil
188
formed by helically winding a conductive wire to serve as an electrical cylindrical conductor and an antenna element formed of a predetermined conductor on a circuit board. In this connection, by using the densely-wound coil
188
as an antenna element, it is possible to prevent the coil
188
from damaging even if it is bent when pulled out of the housing
61
.
In this connection, the densely-wound coil
188
can be also used as the first antenna half-body
83
of the above second and fourth embodiments and sixth and eighth embodiments. By using the coil
188
as the first antenna half-body
83
, it is possible to prevent the coil
188
from damaging even if it is bent at the time of pulling it out of the housing
61
similarly to the case described above.
Moreover, for the above second, fourth, and eighth embodiments, a case is described in which the antenna sections
82
,
102
, and
129
provided with the retractable rod antennas
90
,
103
, and
130
shown in
FIGS. 23A and 23B
,
FIGS. 27A and 27B
and
FIGS. 33A and 33B
are used. However, the present invention is not restricted to the above case. It is also permitted to use an antenna section
191
provided with a retractable rod antenna
190
configured as shown in
FIGS. 48A and 48B
shown by providing the same symbol for a portion corresponding to that in
FIGS. 23A and 23B
, an antenna section
193
provided with a retractable rod antenna
192
configured as shown in
FIGS. 49A and 49B
shown by providing the same symbol for a portion corresponding to that in
FIGS. 27A and 27B
, or an antenna section
195
provided with a retractable rod antenna
194
configured as shown in
FIGS. 50A and 50B
shown by providing the same symbol for a portion corresponding to that in
FIGS. 33A and 33B
.
Actually, in the antenna section
191
shown in
FIGS. 48A and 48B
, the rod-antenna bottom power-supply member
71
is electrically and mechanically connected to the lower end of the second antenna half-body
85
and the upper end of the half-body
85
is inserted into the hole of the first antenna half-body
83
and electrically and mechanically connected to the sliding spring
86
. Moreover, the lower end of the first antenna half-body
83
is provided with the pull-out stop section
84
and the rod-antenna top power-supply member
72
is electrically and mechanically connected to the upper end of the half-body
83
. Thereby, in the antenna section
191
, the retractable rod antenna
190
is formed of the first and second antenna half-bodies
83
and
85
similarly to the case of the antenna section
82
of the above second embodiment.
Moreover, in the antenna section
193
shown in
FIGS. 49A and 49B
, the rod-antenna bottom power-supply member
71
is electrically and mechanically connected to the lower end of the antenna half-body
85
and the upper end of the half-body
85
is inserted into the hole of the first antenna half-body
83
and electrically and mechanically connected to the sliding spring
86
. Furthermore, the pull-out stop section
84
is provided for the lower end of the first antenna half-body
83
and the rod-antenna top power-supply member
72
is electrically and mechanically connected to the upper end of the half-body
83
. Thereby, also in the antenna section
193
, the retractable rod antenna
192
is formed of the first and second antenna half-bodies
83
and
84
similarly to the case of the above fourth embodiment.
Furthermore, in the antenna section
195
shown in
FIGS. 50A and 50B
, the rod-antenna bottom power-supply member
71
is electrically and mechanically connected to the lower end of the second antenna half-body
85
and the upper end of the half-body
85
is inserted into the hole of the first antenna half-body
83
and electrically and mechanically connected to the sliding spring
86
. Moreover, the lower end of the first antenna half-body
83
is provided with the pull-out stop section
84
and the rod-antenna top power-supply member
72
is electrically and mechanically connected to the upper end of the half-body
83
. Thereby, also in the antenna section
195
, the retractable rod antenna
194
is formed of the first and second antenna half-bodies
83
and
84
similarly to the case of the above eighth embodiment.
Furthermore, for the above first to ninth embodiments, a case is described in which the antenna sections
62
,
82
,
93
,
102
,
107
,
114
,
121
,
129
, and
133
are set so as to be freely retracted and pulled out along the longitudinal direction of a housing. However, the present invention is not restricted to the above case. For example, it is also permitted to set the antenna sections
62
,
82
,
93
,
102
,
107
,
114
,
121
,
129
, and
133
so as to be freely retracted and pulled out along the a direction tilted from the longitudinal direction of the housing
61
at the front
61
A of the lower face
61
D of the housing
61
from the back
61
C side of the upper face
61
B of the housing
61
as shown in
FIG. 51
shown by providing the same symbol for a portion corresponding to that in
FIGS. 20 and 24
.
Thereby, it is possible to separate the antenna sections
62
,
82
,
93
,
102
,
107
,
114
,
121
,
129
, and
133
from the head of a user even if a cellular telephone is approached to the head of the user at the time of pulling out the antenna sections
62
,
82
,
93
,
102
,
107
,
114
,
121
,
129
, and
133
. Thus, it is possible to further reduce the deterioration of antenna characteristics of the cellular telephone nearby a human body.
Moreover, for the above first to ninth embodiments, a case is described in which a matching circuit is set between the transceiving circuit
41
and the balun
46
or between the balun
46
on one hand and the first and second antenna elements on the other as described for theory. However, the present invention is not restricted to the above case. As shown in
FIG. 52
, it is also permitted to set the matching circuits
196
and
197
to the balanced and unbalanced sides of the balun
46
.
Furthermore, for the above first to ninth embodiments, a case is described in which a leakage current is prevented from flowing to the ground side of the unbalanced transmission line
42
from the second antenna elements in accordance with the balanced-to-unbalanced transform by the balun
46
. However, the present invention is not restricted to the above case. It is also permitted to prevent a leakage current from flowing to the ground side of the unbalanced transmission line
42
from the first antenna element in accordance with the balanced-to-unbalanced transform by the balun
46
by changing connections of the first and second antenna elements to the balanced-side terminal of the balun
46
.
Furthermore, for the above first to ninth embodiments, a case is described in which the present invention is applied to the above cellular telephones
60
,
80
,
91
,
100
,
105
,
112
,
119
,
127
, and
131
. However, the present invention is not restricted to the above case. It is also possible to widely apply the present invention to various portable radio sets including a cordless handset of a cordless telephone.
Furthermore, for the above first to ninth embodiments, a case is described in which the balun
46
is used as balanced-to-unbalanced transform means for applying balanced-to-unbalanced transform between an unbalanced transmission line on one hand and first and second antenna elements on the other. However, the present invention is not restricted to the above case. As long as balanced-to-unbalanced transform can be applied between first and second antenna elements, various balanced-to-unbalanced transform means can be widely used including the above various baluns.
Furthermore, for the above first to ninth embodiments, a case is described in which the rod-antenna bottom power-supply member
71
, rod-antenna top power-supply member
72
, helical-antenna power-supply members
74
and
125
, top antenna power-supply terminals
77
and
136
, bottom antenna power-supply terminal
78
, and antenna member
123
are used as connection means for electrically connecting first and second antenna elements to a balanced-to-unbalanced transform circuit when the first antenna element is retracted and electrically connecting at least first antenna element to the balanced-to-unbalanced transform circuit when the first antenna element is pulled out. However, the present invention is not restricted to the above case. Other various connection means can be also used as long as they can electrically connect first and second antenna elements to a balanced-to-unbalanced transform circuit when the first antenna element is pushed in and at least first antenna element to the balanced-to-unbalanced transform circuit when the first antenna element is pulled out.
While there has been described in connection with the preferred embodiments of the invention, it will be obvious to those skilled in the art that various changes and modifications may be aimed, therefore, to cover in the appended claims all such changes and modifications as fall within the true spirit and scope of the invention.
Claims
- 1. An antenna device comprising:a first antenna element provided so as to be freely retracted or extended; a second antenna element; an unbalanced transmission line for supplying power to the first and second antenna elements; balanced-to-unbalanced transform means for performing balanced-to-unbalanced transform between the unbalanced transmission line and the first and second antenna elements; and connection means for electrically connecting the first and second antenna elements to the balanced-to-unbalanced transform means when the first antenna element is retracted and electrically connecting at least the first antenna element to the balanced-to-unbalanced transform means when the first antenna element is extended, wherein the first and second antenna elements are operated as antennas by supplying power to the first and second antenna elements from the unbalanced transmission line through the balanced-to-unbalanced transform means when the first antenna element is retracted; and the first antenna element is operated as an antenna by supplying power to at least the first antenna element from the unbalanced transmission line through the balanced-to-unbalanced transform means when the first antenna element is extended.
- 2. The antenna device according to claim 1, whereinthe first antenna element is configured as a rod antenna; and the second antenna element is configured as a helical antenna mechanically connected to the rod antenna.
- 3. The antenna device according to claim 2, whereinthe rod antenna is formed as a collapsible antenna by inserting a conductive rod member into a conductive hollow cylinder and the rod antenna is collapsed when the rod antenna is retracted.
- 4. The antenna device according to claim 1, whereinthe first antenna element is configured as a rod antenna; and the second antenna element is configured as a helically-formed fixed helical antenna and positioned so that the rod antenna is retracted and extended along the helical axis of the helical antenna.
- 5. The antenna device according to claim 1, whereinthe first antenna element is configured as a rod antenna; and the second antenna element is configured as a helically-formed fixed helical antenna and positioned so that the helical axis of the helical antenna is almost parallel to the longitudinal direction of the rod antenna.
- 6. The antenna device according to claim 1, whereinthe first antenna element is configured as a rod antenna; and the second antenna element is configured as a helically-formed fixed helical antenna, having one or both ends electrically connected to the rod antenna to form a composite antenna when the first antenna element is extended.
- 7. A portable radio set having an antenna device, the antenna device comprising:a first antenna element provided so as to be freely retracted and extended; a second antenna element; an unbalanced transmission line for supplying power to the first and second antenna elements; balanced-to-unbalanced transform means for performing balanced-to-unbalanced transform between the unbalanced transmission line and the first and second antenna elements; and connection means for electrically connecting the first and second antenna elements to the balanced-to-unbalanced transform means when the first antenna element is retracted and electrically connecting at least the first antenna element tot he balanced-to-unbalanced transform means when the first antenna element is extended, wherein the first and second antenna elements are operated as antennas by supplying power to the first and second antenna elements from the unbalanced transmission line through he balanced-to-unbalanced transform means when the first antenna element is retracted; and the first antenna element is operated as an antenna by supplying power to at least the first antenna element from the unbalanced transmission line through the balanced-to-unbalanced transform means when the first antenna element is extended.
- 8. The portable radio set according to claim 7, whereinthe first antenna element is configured as a rod antenna; and the second antenna element is configured as a helical antenna mechanically connected to the rod antenna.
- 9. The por table radio set according to claim 8, whereinthe rod antenna is formed as a collapsible an tenna by inserting a conductive rod member into a conductive hollow cylinder and the rod antenna is collapsed when the rod antenna is retracted.
- 10. The portable radio set according to claim 7, whereinthe first antenna element is configured as a rod antenna; and the second antenna element is configured ed as a helically-formed fixed helical antenna and positioned so that the rod antenna is retracted and extended along the helical axis of the helical antenna.
- 11. The portable radio set according to claim 7, whereinthe first antenna element is configured as a rod antenna; and the second antenna element is configured as a helically-formed fixed helical antenna, and positioned so that the helical axis of the helical antenna is almost parallel to the longitudinal direction of the rod antenna.
- 12. The portable radio set according to claim 7, whereinthe first antenna element is configured as a rod antenna; and the second antenna element is configured as a helically-formed fixed helical antenna, having one or both ends electrically connected to the rod antenna to form a composite antenna when the first antenna element is extended.
Priority Claims (1)
Number |
Date |
Country |
Kind |
11-224264 |
Aug 1999 |
JP |
|
US Referenced Citations (3)