Information
-
Patent Grant
-
6229498
-
Patent Number
6,229,498
-
Date Filed
Tuesday, October 12, 199925 years ago
-
Date Issued
Tuesday, May 8, 200123 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
- Jacobson, Price, Holman & Stern, PLLC
-
CPC
-
US Classifications
Field of Search
US
- 343 895
- 343 850
- 343 702
-
International Classifications
-
Abstract
Signal input units 105a to 108a of antenna elements 105 to 108 are held on the essentially same circumference. Signal output units 113b, 113c, 114b, and 114c of a feeding circuit 102 are held on a line which is located perpendicular to a plane where the above-described circumference is located, and also which passes through an essential center of this circumference. The feeding circuit 102 supplies feeding signals to the antenna elements 105 to 108 while applying predetermined phase differences to these feeding signals. As a result, electric lengths of feeding lines 119A to 119D are made coincident with each other. These feeding lines are to connect the signal output units 113b, 113c, 114c to the signal input units 105a to 108a.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is related to a helical antenna used in a mobile wireless (radio) appliance such as a portable telephone.
2. Description of the Related Art
Very recently, mobile communications, e.g., portable telephones are rapidly developed. Not only ground mobile communication systems are available, but also satellite mobile communication systems are expected for practical uses. In such mobile communication terminals, antennas may constitute one of the major important devices, or components.
Now, one example of conventional 4-winding helical antennas will be described with reference to drawings.
FIG. 11
schematically shows an electric power feeding circuit for this conventional helical antenna, and
FIG. 12
is a plan view of the helical antenna to which electric power is supplied by employing the feeding circuit.
An (electric power) feeding circuit
200
is provided with a 3dB-hybrid circuit
201
, a balun circuit
202
, and another balun circuit
203
. These circuits
201
to
203
are mounted, or packaged on the same plane of a mounting board
204
under such a condition that these circuits
201
to
203
are connected via a strip line having a resistance value of 50 Ω to each other.
The hybrid circuit
201
is a circuit for producing an output signal whose output phase is in phase with the input phase thereof (will be defined as a “0° output” hereinafter), and another output signal whose output phase is delayed by 90° from the input phase thereof (will be defined as a “90° output” hereinafter) from a signal which is supplied to the antenna for feeding the electric power. It should be noted that an output signal whose output phase is delayed by 180° from the input phase thereof is defined as a “180° output”, and an output signal whose output phase is delayed by 270° from the input phase thereof is defined as a “270° output”.
The balun circuit
202
contains a signal output unit
205
and another signal output unit
206
. The 0° output derived from the hybrid circuit
201
is entered into the signal output circuit
205
and the signal output circuit
206
, respectively. The signal output units
205
and
206
produce both the 0° output and the 180° output with respect to this input signal of the 0° output as feeding signals, and then output these feeding signals.
The balun circuit
203
contains a signal output unit
207
and another signal output unit
208
. The 90° output derived from the hybrid circuit
201
is entered into the signal output circuit
207
and the signal output circuit
208
, respectively. The signal output units
207
and
208
produce both the 0° output and the 180° output with respect to this input signal of the 90° output as feeding signals, and then output these feeding signals.
As a consequence, the relationship among these feeding signals is established as follows: That is, with respect to the 0° output of the signal output unit
205
, the 180° output derived from the signal output unit
206
is delayed by 180°; the 0° output derived from the signal output unit
207
is delayed by 90°; and the 180° output derived from the signal output unit
208
is delayed by 270°.
In a helical antenna
210
, 4 pieces of antenna elements (not shown) are arranged in a helical form along an outer surface of a hollow cylindrical body
211
.
Each of the antenna elements owns each of signal input units
212
to
215
. The respective signal input units
212
to
215
are arranged in an equi-interval of 90 degrees on an edge portion of the cylindrical body
211
, and also are connected to the respective signal output units
205
to
208
via a power feeding line
216
made of a conductive line with maintaining an individual relationship among them.
As a result, the power feeding signals are supplied from the feeding circuit
200
to the respective antenna elements under such a condition that the phase differences among these feeding signals are made by 90 degrees.
On the other hand, the signal input units
212
to
215
of the respective antenna elements are arranged on an edge surface of the cylindrical body
211
, namely on a circumference within the same plane.
However, the respective signal output units
205
to
208
of the feeding circuit
200
are arranged on the same straight line at an edge portion on the mounting plane of the board
204
.
As a result, the connection distances “a” to “d” between the signal output units
205
to
208
and the signal input units
212
to
215
are made incoincident with each other.
In the case of the antenna arrangement shown in
FIG. 12
, the connection relationship is given by d>a≅b>c. In particular, a distance difference between a connection distance “c” (interval between
207
and
213
) and another connection distance “d” (interval between
208
and
215
) becomes large.
As previously explained, while the connection distances “a” to “d” are made incoincident with each other, if the signal output units
205
to
208
are connected to the signal input units
212
to
215
by way of the feeding lines
216
(
a
) to
216
(
d
), then a large difference is produced in the lengths (electric lengths) of the feeding lines
216
(
a
) to
216
(
d
).
As a consequence, the feeding signals having the phase differences by 90 degrees are not originally supplied to the respective antenna elements. Accordingly, the axial ratio of the radiated circularly-polarized wave is increased. Furthermore, the horizontal plane directivity of this helical antenna is deteriorated. As a result, the signal transmission/reception cannot be carried out in high precision.
SUMMARY OF THE INVENTION
Accordingly, a major object of the present invention is to provide a helical antenna capable of transmitting/receiving a signal in high precision, while increasing precision in a phase difference of electric power feeding to the respective antenna elements.
Other objects, features, and advantages of the present invention may become apparent from the below-mentioned descriptions.
To achieve the above-described objects of the present invention, a helical antenna according to an aspect of the present invention, is featured by comprising: a plurality of antenna elements, each of which antenna elements having a signal input unit for an electric power feeding signal; feeding means having at least plural signal output units corresponding to the number of the signal input units, for outputting the feeding signals from the respective signal output units while giving a predetermined phase difference to the feeding signals; a first holding mechanism for holding the respective signal input units of the antenna elements on the substantially same circumference; a second holding mechanism for holding the respective signal output units of the feeding means on a line which is located perpendicular to a plane where the circumference is positioned, and also which passes through an essential center of the circumference; and a plurality of feeding lines for connecting the respective signal input units of the respective antenna elements to the respective signal output units of the feeding means with maintaining the individual relationship among them.
In the helical antenna, in view of the geometrical aspect, separation distances between one point on the line which passes through the essential center of the above-explained circumference and the arranging positions of the respective signal input units will become constant. As a consequence, in accordance with the present invention, since the signal output units are held on the above-explained line, the lengths of the respective feeding lines can be made substantially equal to each other. Namely, the separation intervals between the signal output units and the signal input units corresponding thereto can be made substantially coincident with each other.
BRIEF DESCRIPTION OF THE DRAWINGS
The remaining object of the invention will become apparent from the understanding of embodiment to be described hereinafter and will be clarified in the appended claims of the invention. A number of advantages, not touched upon herein, will be noticed by those skilled in the art, if the invention is practiced.
FIG. 1
is a perspective view for representing an outer view of the 4-winding helical antenna according to a first preferred embodiment of the present invention;
FIG. 2
is a plan view for showing the helical antenna of
FIG. 1
;
FIG. 3
is a perspective view for representing an outer view of a main body of the helical antenna shown in
FIG. 1
;
FIG. 4
is a fragmentary perspective view for indicating a feeding circuit of the helical antenna shown in
FIG. 1
;
FIG. 5
is a sectional view of the helical antenna, taken along a line A—A of
FIG. 4
;
FIG. 6
is a fragmentary perspective view for representing a feeding circuit of an antenna element as one modification of
FIG. 1
;
FIG. 7
is a fragmentary perspective view for indicating a major portion of an antenna element as another modification of
FIG. 1
in an enlarged form;
FIG. 8
is a plan view for representing a helical antenna according to a second preferred embodiment of the present invention;
FIG. 9
is a fragmentary perspective view for representing a feeding circuit of the helical antenna shown in
FIG. 8
;
FIG. 10
is a fragmentary perspective view for showing a feeding circuit of an antenna element as a modification of
FIG. 9
;
FIG. 11
is a plan view for showing the feeding circuit of the conventional helical antenna; and
FIG. 12
is a plan view for indicating the conventional helical antenna of FIG.
11
.
DETAILED DESCRIPTION OF THE INVENTION
Referring now to drawings, various preferred embodiments of the present invention will be described in detail.
Referring to
FIG. 1
to
FIG. 5
, reference numeral
100
shows a 4-winding helical antenna according to a first preferred embodiment of the present invention.
This helical antenna
100
is provided with an antenna main body
101
, a (electric power) feeding circuit
102
, and a (electric power) feeding connector
103
.
The antenna main body
101
is equipped with a hollow cylindrical body
104
made of resin such as tetrafluoroethylene.
4 pieces of antenna elements
105
to
108
are provided on an outer peripheral surface of this cylindrical body
104
. The antenna elements
105
to
108
are made of a conductive line mainly containing copper as a main material.
The respective antenna elements
105
to
108
are provided on the outer peripheral surface of the cylindrical body
104
in a helical shape with an equi-pitch and also an equi-interval.
Each of these antenna elements
105
to
108
has signal input portions
105
a
to
108
a
into which feeding signals are inputted, respectively. Each of these signal input portions
105
a
to
108
a
is provided on either an edge surface of the cylindrical body
104
or a place in the vicinity of this cylindrical body
104
, otherwise, preferably on one edge
104
a
of this cylindrical body
104
.
The respective signal input portions
105
a
to
108
a
are arranged in an equi-interval of 90 degrees along one edge
104
a
. Since such an arrangement is employed, the respective signal input portions
105
a
to
108
a
are held on the substantially same circumference within the substantially same plane. This cylindrical body
104
will constitute a first holding mechanism for holding the signal input portions
105
a
to
108
a.
All of the antenna elements
105
to
108
are short circuited at the other edge
104
b
of the cylindrical body
104
.
The feeding circuit
102
is mounted on a circuit board manufactured by stacking a plurality of boards, namely a stacked layer board
110
. The stacked layer board
110
is held within the cylindrical body
104
in such a manner that an edge portion of this stacked layer board
110
is located within a plane which passes through the edge
104
a
of the cylindrical body
104
.
The stacked layer board
110
is constructed in such a manner that a ground layer
111
is interposed between one pair of dielectric boards
110
A and
110
B such as a glass epoxy board.
A width “H” of the stacked layer board
110
is made slightly smaller than an inner diameter of the cylindrical body
104
in such a manner that the stacked layer boards
110
are stored into the cylindrical body
104
under stable state without any space along the radial direction. Both a 3-dB hybrid circuit
112
and a balun circuit
113
are mounted on one surface
110
a
of the stacked layer board
110
. This one surface
110
a
is located on the outside of the dielectric board
110
A.
The balun circuit
114
is mounted on the other surface
110
b
of the stacked layer board
110
, and the other surface
110
b
is located on the outside of the dielectric board
10
B.
The balun circuits
113
and
114
are arranged with sandwiching the stacked layer board
110
in such a manner that the balun circuit
113
is located opposite to the balun circuit
114
along the thickness direction thereof.
The hybrid circuit
112
contains a signal input unit
112
a
connected to the feeding connector
103
, another signal output unit
112
b
for outputting a 0° output of this hybrid circuit
112
, and also a further signal output unit
112
c
for outputting a 90° output thereof.
The balun circuit
113
enters thereinto the 0° output supplied from the signal output unit
112
b
of the hybrid circuit
112
, and produces a 0° output and a 180° output as a feeding signal to output these 0° output and 180° output. This 0° output will be referred to as a “0° feeding output”, as viewed from the feeding circuit
102
, whereas the 180° output will be referred to as a “180° feeding output ”, as viewed from the feeding circuit
102
with respect to this inputted 0° output.
The balun circuit
114
enters thereinto the 90° output supplied from the signal output unit
112
c
of the hybrid circuit
112
, and produces a 0° output and a 180° output as a feeding signal to output these 0° output and 180° output. This 0° output will be referred to as a “90° feeding output”, as viewed from the feeding circuit
102
, whereas the 180° output will be referred to as a “270° feeding output”, as viewed from the feeding circuit
102
with respect to this inputted 90° output.
It should be noted that the signal output unit
112
b
of the hybrid circuit
112
is connected to an unbalance terminal
113
a
of the balun circuit
113
via a signal line
115
having a resistance value of 50 Ω formed on the plane
110
a
of the stacked layer board
110
.
The signal output unit
112
c
of the hybrid circuit
112
is connected to the unbalance terminal
114
a
of the balun circuit
114
via another 50 Ω-signal line
116
formed on the plane
110
a
of the stacked layer board
110
, a throughhole electrode
117
formed on the board
110
by penetrating this board
110
, and another 50 Ω-signal line
118
formed on the plane
110
b
of the board
110
.
A notch
111
a
is formed in the ground layer
111
. This notch
111
a
allows the throughhole electrode
117
to penetrate this notch
11
a
under electrically insulating condition.
The balun circuit
113
owns a signal output unit
113
b
for the 0° feeding output, and another signal output unit
113
c
for the 180° feeding output. This signal output unit
113
c
is extended up to a board edge
110
c
on one plane
110
a
of the board
110
. This board edge
110
c
is located in the vicinity of the balun circuits
113
and
114
.
The balun circuit
114
owns a signal output unit
114
b
for the 90° feeding output, and another signal output unit
114
c
for the 270° feeding output. This signal output unit
114
c
is extended up to the board edge portion
110
c
on the other plane
110
b
of the board
110
.
Both the signal output units
113
b
and
113
c
of the balun circuit
113
are extended up to the edge portion
110
c
of the stacked layer board
110
by way of the 50 Ω-signal line. These signal output units
113
b
and
113
c
are arranged in the vicinity of a central portion of the plane
110
a
of the board
110
along the width “H” direction on this plane
110
a
. Furthermore, these signal output units
113
b
and
113
c
are arranged close to each other as being permitted as possible along the plane direction to such a degree that these signal output units
113
b
and
113
c
do not cause an electrical problem by each other.
Both the signal output units
114
b
and
114
c
of the balun circuit
114
are arranged in the vicinity of a central portion of the other plane
110
b
of the board
110
along the width “H” direction on this plane
110
b
. Furthermore, these signal output units
114
b
and
114
c
are arranged close to each other as being permitted as possible along the plane direction to such a degree that these signal output units
114
b
and
114
c
do not cause an electrical problem by each other.
In other words, each of these signal output units
113
b
to
114
c
is penetrated through an essential center on the same circumference on the edge
104
a
of the cylindrical body
104
, namely within a plane, and then is held on a line perpendicular to this plane.
In this case, the stacked layer board
110
will constitute a second holding mechanism for holding these signal output units
114
b
and
114
c.
The board edge portion
110
c
formed on one plane
110
a
of the board
110
will constitute a first arranging portion on which the signal output units
113
b
and
113
c
are arranged. The board edge portion
110
c
formed on the other plane
110
b
of the board
110
will constitute a second arranging portion on which the signal output units
114
b
and
114
c
are arranged. Then, an arranging portion is constituted by these first arranging portion and second arranging portion.
Both the hybrid circuit
112
and the balun circuit
113
formed on one plane will constitute a first phase adjusting circuit. The balun circuit
114
will constitute a second phase adjusting circuit.
The feeding circuit
102
equipped with the above-described arrangement is inserted into an internal space of the cylindrical body
104
to be arranged therein, while satisfying the below-mentioned conditions:
(1) A condition under which the edge
110
c
of the stacked layer board
110
is located on the side of the edge
104
a
of the cylindrical body
104
.
(2) A condition under which the edge
110
c
of the stacked layer board
110
is positioned substantially coincident with the edge
104
a
of the cylindrical body
104
.
(3) A condition that the direction of the width “H” of the stacked layer board
110
is made coincident with the opposite direction of either the combination between the signal input units
105
a
and
107
a
or the combination between the signal input units
106
a
and
108
a
, which are intersected with each other at a right angle (it should be noted that in FIG.
1
and
FIG. 2
, opposite direction of signal input portions
106
a
and
108
a
is made coincident with direction of width “H” of stacked layer board
110
).
As previously explained, in this case, as to the feeding circuit
102
, the width “H” of the board
110
is set to be slightly smaller than the inner diameter of the cylindrical body
104
, and furthermore, the arranging position between the signal output units
113
b
/
113
c
of the balun circuit
113
and the signal output units
114
b
/
114
c
of the balun circuit
114
is set to the central portion of the board
110
along the width “H” direction.
As a result, the feeding circuit
102
stored in the cylindrical body
104
is arranged without any space along the radial direction of the cylindrical body
104
. All of the signal output units
113
b
to
114
c
are arranged at positions which are made substantially coincident with an axial center “α” of the cylindrical body
104
. This axial center “α” corresponds to the helical axes of the antenna elements
105
to
108
.
As a consequence, all of the signal output units
113
b
to
114
c
may pass through the essential center of the above-explained circumference along which all of the corresponding signal input units
105
a
to
108
a
are arranged.
After the feeding circuit
102
has been stored into the cylindrical body
104
, the respective signal output units
113
b
to
114
c
and also the respective signal input units
105
a
to
108
a
are connected to feeding lines
119
A to
119
D corresponding thereto.
As the first holding mechanism, the present invention is not limited to such a cylindrical body
104
, the section of which is a circle, but other shaped cylinder bodies may be employed, the sections of which are selected from an elliptical shape, a polygonal shape, and so on. Also, the first holding mechanism may be realized by such a cylinder body having different diameters along an axial direction thereof, other than another cylinder body having a uniformly equal diameter along the axial direction.
When the respective signal output units
113
b
to
114
c
are connected to the respective signal input units
105
a
to
108
a
in the above-described manner, the electric lengths of the respective feeding lines
119
A to
119
D are made substantially equal to each other. In other words, the separation distances between the respective signal input units
105
a
to
108
a
formed on the edge
104
a
, and one point of the axial center “α” of the cylindrical body
104
may be made constant in view of the geometrical aspect. One point of this axial center “α” corresponds to one point on a vertical line of the arranging place of this circle, which passes through the essential center of the circumference along which the signal input units
105
a
to
108
a
are arranged.
As previously explained, the positions of the respective signal output units
113
b
to
114
c
are made substantially coincident with the axial center “α” of the cylindrical body
104
. That is to say, the respective signal output units
113
b
to
114
b
are arranged close to one point on the axial center “α” of the cylindrical body
104
(namely, axial center “α” located on edge
104
a
) as being permitted as possible. As a consequence, the lengths of the respective feeding lines
119
A to
119
D are made substantially identical to each other, and these feeding lines
119
A to
119
D are used to connect the signal input units
105
a
to
108
a
with the respective signal output units
113
b
to
114
c.
Moreover, since the positions of the respective signal output units
113
b
to
114
c
on the axial center “α” are made substantially identical to the positions of the respective signal input units
105
a
to
108
a
on the axial center “α”, the electric lengths of the respective feeding lines
119
A to
119
D are made minimum, so that a better electric characteristic (resistance characteristic and so on) of the helical antenna can be achieved.
When signal transmission/reception are carried out by using the helical antenna
100
equipped with the above-described antenna structure, this helical antenna
100
may represent such a directivity characteristic having a conical beam characteristic with respect to the vertical plane. At this time, since the electrical lengths of the feeding lines
119
A to
119
D are substantially identical to each other, the power feeding phases to the respective elements
105
to
108
become correctly 90° different from each other. As a result, the circularly-polarized wave having the small axial ratio (nearly 0 dB) to the main radiation direction is irradiated with having the omnidirectional characteristic along the horizontal direction, and thus, the radiation characteristic is not deteriorated. For instance, as this deterioration of the radiation characteristic, the axial ratio of the radiated circularly-polarized wave is increased, and the horizontal plane directivity characteristic is deteriorated. In other words, in accordance with this helical antenna
100
, the stable circularly-polarized wave can be radiated over the wide angle.
In this first preferred embodiment, the signal output unit
112
c
of the hybrid circuit
112
is connected to the signal output unit
114
a
of the balun circuit
114
via the throughhole electrode
117
, the 50 Ω-signal line
116
, and the 50 Ω-signal line
118
, which are formed on the board
110
. Alternatively, this connection may be carried out by employing not the above-described throughhole electrode, but other structures such as a jumper line. When such a modified structure is employed, no longer the notch
111
a
is formed in the ground layer
111
, resulting in one-plane ground. This “one-plane ground” can be readily manufactured, so that the manufacturing steps for the board
110
may become easy.
Also, a helical-shaped groove capable of storing thereinto the antenna elements may be formed in an outer peripheral surface of the cylindrical body
104
, and the respective antenna elements
105
to
108
may be stored in this helical-shaped groove. As a result, the shapes of the antenna elements
105
to
108
may be made in high precision, and furthermore, these antenna elements
105
to
108
may be readily stored/arranged. Accordingly, the electric characteristic of the 4-winding helical antenna may be stabilized, and moreover, this 4-winding helical antenna may be manufactured in a simple manner.
Although the feeding circuit
102
is inserted into the cylindrical body
104
so as to be arranged therein in this preferred embodiment, this feeding circuit
102
may be alternatively arranged in such a manner that this feeding circuit
102
is not inserted/arranged within the cylindrical body
104
. In this alternative case, a similar effect may be achieved even when the following structure is employed. That is, for example, while the feeding circuit
102
is arranged at a lower portion of the cylindrical body
104
, a feeding point is arranged at the lower portion of this cylindrical body
104
, and 4 pieces of antenna elements
105
to
108
are short circuited at an upper portion of the cylindrical body
104
. This feeding point corresponds to a joint point between the signal output units
113
b
to
114
c
and the signal input units
105
a
to
108
a.
Also, in this first preferred embodiment, the feeding circuit
102
is arranged at such a position that the respective signal output units
113
b
to
114
b
are made coincident with the edge portion
104
a
on the axial center “α”. Alternatively, the respective signal output units
113
b
to
114
b
may not be made coincident with the edge portion
104
a
on the axial center “α”. In principle, the respective signal output units
113
b
to
114
b
may be arranged in such a way that these signal output units
113
b
to
114
b
are located close to one point on the axial center
Further, in this first preferred embodiment, the cylindrical body
104
is made of tetrafluorethylene. Alternatively, this cylindrical body
104
may be made of other resin such as polypropylene, or film-shaped resin. Also, the copper wires are employed so as to manufacture the antenna elements
105
to
108
. Alternatively, even when the antenna elements are directly printed, or directly plated on the cylindrical body
104
made of resin, a similar effect may be achieved. In addition, in such a case that the cylindrical body
104
is formed in a film shape, the antenna elements maybe easily printed, or plated on this film-shaped cylindrical body
104
.
In this first preferred embodiment, the hybrid circuit
112
is directly connected to both the balun circuits
113
and
114
via the 50 Ω-signal line
115
, the 50 Ω-signal line
116
, the throughhole electrode
117
, and also the 50 Ω-signal line
118
. Alternatively, as shown in
FIG. 7
, either an impedance matching circuit
20
or another impedance matching circuit
21
may be inserted into the signal line connected to the 50 Ω-signal line
115
and the 50 Ω-signal line
118
. After the output signal of the hybrid circuit
112
is processed by these impedance matching circuits
20
and
21
, the processed signal may be inputted into the balun circuit
113
and the balun circuit
114
. In this alternative case, the impedance of the antenna may be matched, so that the reflection loss caused by the mismatching operation can be reduced, and the electromagnetic wave can be irradiated from this antenna in a high efficiency.
Also, in this first preferred embodiment, the inventive idea of the present invention is embodied in the helical antenna equipped with the four antenna elements
105
to
108
. A total number of antenna elements is not limited to four elements, but may be similarly applied to other numbers. That is, apparently, the present invention may be embodied in a helical antenna equipped with a plurality of antenna elements other than 4 elements. More specifically, when the inventive idea of the present invention is embodied in such a helical antenna equipped with plural antenna elements, the quantity of which is equal to a multiple number of 2, a feeding means may be constituted by way of a circuit arrangement substantially similar to that of the above-described embodiment.
Also, in accordance with this first preferred embodiment, since the groove is digged in the cylindrical body
104
made of the resin so as to wind thereon the antenna elements
105
to
108
, the antenna shape can be maintained under stable condition, and furthermore the electric characteristic of the helical antenna can be stabilized as well as can be manufactured in an easy manner.
Also, in this first preferred embodiment, the feeding line is constituted by the conductive wire. Alternatively, as shown in
FIG. 7
, a feeding line
121
may be constituted by a wiring pattern formed on an insulating board
120
. In this alternative case, the length of this feeding line
121
may be continuously kept constant without any loose line portion, so that there is no error in the length of the wired feeding line
121
.
Also, in order to connect/fix the board
120
to the cylindrical body
104
, the feeding line
121
may be connected to the signal input units
105
a
to
108
a
by using either soldering agent or conductive adhesive agent under such a condition that the board
120
abuts against the edge portion
104
a
of the cylindrical body
104
. In this alternative case, the feeding line
121
may be connected to the signal input units
105
a
to
108
a
in a simpler manner than that of the above-explained feeding line made of the conductive wire.
Moreover, in this alternative case, the board
120
may be supported/fixed to one edge portion
104
a
of the cylindrical body
104
by way of the adhesive forces produced by the soldering agent and the conductive adhesive agent.
Alternatively, if the feeding line
121
is formed on the board
120
in the form of a wiring pattern, then the board
110
for mounting thereon the feeding circuit
102
may be connected/fixed on the insulating board
120
. In this alternative case, the board
110
may be mounted inside the cylindrical body
104
under such a condition that this board
110
is connected/fixed on the insulating board
120
. As a result, the work required to support/fix the board
110
maybe simplified.
Furthermore, this insulating board
120
may be made in an integral form with the cylindrical body
104
.
Next, a helical antenna according to a second preferred embodiment of the present invention will now be explained with reference to FIG.
8
and FIG.
9
. As shown in the drawings, the signal input units
105
a
to
108
a
of the antenna elements
105
to
108
are arranged in an equi-interval on the edge portion
104
a
along the circumferential direction every angle of 90° (90 degrees).
A feeding circuit
130
is provided on the insulating board
110
. Signal output units
133
b
to
134
c
of this feeding circuit
130
are arranged on the board edge portion
110
c
of the board
110
.
The respective signal output units
133
b
to
134
c
are arranged on a circumference of a circle “β” on the board edge portion
110
c
with respect to a center “γ” of the edge portion along a longitudinal direction.
The signal output unit
133
b
for the 0° output, the signal output unit
133
c
for the 90° output, the signal output unit
134
b
for the 180° output, and the signal output unit
134
c
for the 270° output are sequentially arranged on the circle “β” in a substantially equi-interval along the circumferential direction in this order.
To arrange these signal output units
133
b
to
134
c
in this manner, the feeding circuit
130
is constituted as follows:
Both a 3-dB-hybrid circuit
133
and a balun circuit
132
are mounted on one surface
110
a
of the board
110
. This one surface
110
a
is located on the outside of the dielectric board
110
A.
A 3-dB-hybrid circuit
134
is mounted on the other surface
110
b
of the board
110
, and the other surface
110
b
is located on the outside of the dielectric board
110
B.
The balun circuits
133
and
134
are arranged with sandwiching the board
110
in such a manner that the balun circuit
133
is located opposite to the balun circuit
134
along the thickness direction thereof.
The balun circuit
132
produces both a 0° output and a 180° output, whereas the hybrid circuits
133
and
134
produce both a 0° output and a 90° output from the output derived from the balun circuit
132
.
A power feeding connector
103
(not shown) is connected to an input unit
132
a
of the balun circuit
132
.
The signal output unit
132
b
for 0° output of the balun circuit
132
is connected to an unbalance terminal
133
a
of the hybrid circuit
133
via a signal line
135
having a resistance value of 50 Ω formed on the plane
110
a
of the board
110
.
The signal output unit
132
c
for 180° output of the balun circuit
132
is connected to the unbalance terminal
134
a
of the hybrid circuit
134
via another 50 Ω-signal line
136
formed on the plane
110
a
of the insulating board
110
, a throughhole electrode
137
formed on the board
110
by penetrating this board
110
, and another 50 Ω-signal line
138
formed on the plane
110
b
of the board
110
.
A notch
111
a
is formed in the ground layer
111
. This notch
111
a
allows the throughhole electrode
137
to penetrate this notch
111
a
under electrically insulating condition.
Both the signal output unit
133
b
for 0° output of the hybrid circuit
133
and the signal output unit
133
c
for 90° output thereof extended up to the board edge portion
110
c
which is located in the vicinity of the balun circuits
133
and
134
, on one surface
110
a
of the board
110
.
Both the signal output unit
134
b
for 90° output of the hybrid circuit
134
and the signal output unit
134
c
for 0° output thereof are extended up to the board edge portion
110
c
which is located in the vicinity of the balun circuits
133
and
134
, on the other surface
110
b
of the board
110
.
The respective signal output units
133
b
to
134
c
are extended up to the board edge portion
110
c
by way of the 50 Ω-signal line.
The signal output units
133
b
and
133
c
are arranged at symmetrical positions on one surface
110
a
of the board
110
while sandwiching the center along the board width direction, namely positions separated from a center of the board width by the same distances.
The signal output units
134
b
and
134
c
are arranged at symmetrical positions on the other surface
110
b
of the board
110
while sandwiching the center along the board width direction.
With employment of the above-described arrangement, both the signal output units
133
b
/
133
c
and the signal output units
134
b
/
134
c
are sequentially arranged in an equi-interval of 90° in this order of 0°-output, 90°-output, 180°-output, and 270°-output at such positions. That is, these positions are separated from each other by the phase angle of approximately 90 degrees on the circle “β” while setting as a center the center “γ” of the board edge portion
110
c
of the board
110
along the width direction.
It should be also noted that the phase delay amounts of these outputs may be shifted from each other by the angle of essentially 90 degrees. Moreover, these phase shift amounts may be approximated to 90 degrees as close as possible, but need not be correctly set to 90 degrees, as apparent from the foregoing description.
The feeding circuit
130
equipped with the above-described arrangement is inserted into an internal space of the cylindrical body
104
to be arranged therein, while satisfying the below-mentioned conditions:
(1) A condition under which the edge portion
110
c
of the board
110
is located on the side of the edge portion
104
a
of the cylindrical body
104
. The respective signal output units
133
b
to
134
c
are provided on the edge portion
110
c
, and the respective signal input units
105
a
to
108
a
are provided on the edge portion
104
a.
(2) A condition under which the edge portion
110
c
of the board
110
is positioned substantially coincident with the edge portion
104
a
of the cylindrical body
104
.
(3) A condition under which the direction of the board
110
is set in such a manner that the arranging phase angles of the signal output units
133
b
to
134
c
on the board edge portion
110
a
are made coincident with those of the signal input units
105
a
to
108
a
on the edge portion
104
a.
As a result, the circle “β” is arranged at a position on the edge portion
104
a
, and this position is located in a coaxial manner with respect to the cylindrical body
104
. Both the signal output units
133
b
to
134
c
and the signal input units
105
a
to
108
a
are arranged in such a manner that the signal output units are separated from the signal input units in an equi-interval along the circumferential direction on the respective circumferences of two circles (namely, circle “β” and edge portion
104
a
) which are positioned in a coaxial manner.
Both the signal output units
133
b
to
134
c
and the signal input units
105
a
to
108
a
are arranged at the same phase angle positions, and are arranged at positions located along the radial direction of the circle “β” under such a condition that these signal output/input units are positioned in an one-to-one correspondence relationship.
After the feeding circuit
130
has been stored into the cylindrical body
104
, both the signal output units
133
b
to
134
c
and the signal input units
105
a
to
108
a
are connected to each other by using a power feeding line
135
made of a conductive wire and the like. These signal output/input units are arranged on the same radius of the circle “β”. In other words, the signal output unit
133
b
for 0° output is connected via a power feeding line
135
A to the signal input unit
105
a
. The signal output unit
133
c
for 90° output is connected via a power feeding line
135
B to the signal input unit
106
a
. This signal input unit
106
a
is arranged apart from the signal input unit
105
a
at an angle of 90 degrees along a left turning direction, as viewed in this drawing. The signal output unit
134
c
for 180°-delayed output is connected via a power feeding line
135
C to the signal input unit
107
a
. This signal input unit
107
a
is arranged apart from the signal input unit
106
a
at an angle of 90 degrees along a left turning direction, as viewed in this drawing. The signal output unit
134
b
for 270° output is connected via a power feeding line
135
D to the signal input unit
108
a
. This signal input unit
108
a
is arranged apart from the signal input unit
107
a
at an angle of 90 degrees along a left turning direction, as viewed in this drawing.
When the respective signal output units
133
b
to
134
c
are connected to the respective signal input units
105
a
to
108
a
in the above-described manner, the electric lengths of the respective feeding lines
135
A to
135
D are made substantially equal to each other. In other words, as previously explained, the respective signal input units
105
a
to
108
a
are formed on the edge portion
104
a
in an equi-interval along the circumferential direction. The signal output units
133
b
to
134
b
are provided in an equi-interval along the circumferential direction on the circumference of such a circle positioned in a coaxial manner with respect to the cylindrical body
104
. In this concrete example, as one example, this circle corresponds to a circle “β” positioned in a coaxial manner with respect to the edge portion
104
a
. As a result, the separation distances between the signal input units
105
a
to
108
a
and the signal output units
133
b
to
133
c
will become constant in view of the geometrical aspect. These signal output units
133
b
to
134
c
are located at the nearest positions with respect to these signal input units. As a consequence, the length of the respective feeding lines
135
A to
135
D are made substantially identical to each other, and these feeding lines
135
A to
135
D are used to connect the signal input units
105
a
to
108
a
with the respective signal output units
133
b
to
134
c
, resulting in a similar effect to that of the first preferred embodiment.
Moreover, since the signal output units
133
b
to
134
c
are provided at the positions defined at the same phase angles with the signal input units
105
a
to
108
a
on the circumference of the circle “β”, the separation distances between the signal input units
105
a
to
108
a
and the signal output units
133
b
to
134
b
will become the shortest lengths in view of the geometrical aspect. Accordingly, the lengths of the respective feeding lines
135
A to
135
D for connecting the signal input units
105
a
to
108
a
with the respective signal output units
133
b
to
134
c
can be made shorter, so that a better electric characteristic (resistance characteristic and so on) can be achieved.
Furthermore, since the arranging plane of the circle “β” is made coincident with the setting position of the edge portion
104
a
, the electric lengths of the respective feeding lines
135
A to
135
D are made minimum, so that a better electric characteristic (resistance characteristic and so on) of the helical antenna can be achieved.
In this second embodiment, the feeding circuit
130
is arranged in such a manner that the plane where the circle “β” is arranged is made coincident with the edge portion
104
a
. Alternatively, according to the present invention, the arranging plane of this circle “β” may not be made coincident with the edge portion
104
a
. Essentially speaking, the circle “β” may be arranged in parallel to the edge portion
104
a
with keeping a coaxial relationship.
In this case, the stacked layer board
110
constitutes the insulating board. The cylindrical body
104
constitutes a first holding mechanism. The stacked layer board
110
constitutes a second holding mechanism. Both the balun circuit
132
and the hybrid circuit
133
constitute a first phase adjusting circuit. The hybrid circuit
134
constitutes a second phase adjusting circuit. The edge portion
104
a
of the cylindrical body
104
constitutes the circumference on which the signal input units are arranged. The circle “β” constitutes another circumference.
The board edge portion
110
c
formed on one plane
110
a
of the board
110
will constitute a first arranging portion on which the signal output units
133
b
and
133
c
are arranged. The board edge portion
110
c
formed on the other plane
110
b
of the board
110
will constitute a second arranging portion on which the signal output units
134
b
and
134
c
are arranged. Then, an arranging portion is constituted by these first arranging portion and second arranging portion.
As the first holding mechanism, also in this second embodiment, the present invention is not limited to such a cylindrical body
104
, the section of which is a circle, but other shaped cylinder bodies may be employed, the sections of which are selected from an elliptical shape, a polygonal shape, and so on. Also, the first holding mechanism may be realized by such a cylinder body having different diameters along an axial direction thereof, other than another cylindrical body having a uniformly equal diameter along the axial direction.
In this second embodiment, in order that the signal output unit
133
b
for the 0° output, the signal output unit
133
c
for the 90° output, the signal output unit
134
c
for the 180° output, and the signal output unit
134
b
for the 270° output are sequentially arranged on this circle “β” in this order, the feeding circuit
140
may be arranged as follows:
That is to say, as illustrated in
FIG. 10
, in the board
110
, both the 3-dB-hybrid circuit
141
and the balun circuit
142
are mounted on one plane
110
a
which is located outside the dielectric board
110
A. The balun circuit
143
is mounted on the other plane
110
b
which is located outside the dielectric board
110
B. The balun circuit
142
is arranged opposite to the balun circuit
143
along the thickness direction by sandwiching the board
110
.
The hybrid circuit
141
produces the 0°-output and the 90°-output, whereas both the balun circuits
142
and
143
produce the 0°-output and the 180°-output from the outputs of the hybrid circuit
141
.
A power feeding connector (not shown)
103
is connected to the input unit
141
a
of the hybrid circuit
141
.
The signal output unit
141
b
of the 0°-output from the hybrid circuit
141
is connected to an unbalance terminal
142
a
of the balun circuit
142
via the 50 Ω-signal line
144
provided on one plane
111
a
of the board
110
.
The signal output circuit
141
c
for 90°-delayed output of the hybrid circuit
141
is connected to the unbalance terminal
143
a
of the balun circuit
143
via a 50 Ω-signal line
145
formed on the plane
110
a
of the stacked layer board
110
, a throughhole electrode
146
formed on the board
110
by penetrating this board
110
, and another 50 Ω-signal line
147
formed on the other plane
110
b
of the board
110
.
The above-described 50 Ω-signal line
147
owns a signal line length of λy/4 (symbol “λy” being wavelength) so as to delay a signal by only 90 degrees.
A notch
111
a
is formed in the ground layer
111
. This notch
111
a
allows the throughhole electrode
137
to penetrate this notch
111
a
under electrically insulating condition.
The signal output unit
142
b
and another signal output unit
142
c
of the balun circuit
142
are extended up to the board edge portion
110
c
on one plane
110
a
of the board
110
. This board edge portion
1110
c
is located in the vicinity of the balun circuits
142
and
143
.
The signal output unit
143
b
and another signal output unit
144
c
of the balun circuit
143
are extended up to the board edge portion
110
c
on the other plane
110
b
of the board
110
. This board edge portion
110
c
is located in the vicinity of the balun circuits
143
and
144
.
Both the signal output units
142
b
and
143
c
are extended up to the edge portion
110
c
of the board
110
by way of the 50 Ω-signal lines
148
and
149
. Both the signal output units
142
c
and
143
b
are extended up to the board edge portion
110
c
by way of the 50 Ω-signal lines
150
and
151
.
These 50 Ω-signal lines
150
and
151
own signal line lengths of λy/4 (symbol “λy” being wavelength) so as to delay a signal by 90 degrees.
With employment of the above-described arrangement, the signal output unit
142
b
constitutes the 0°-output signal output unit of the feeding circuit
140
, the signal output unit
142
c
constitutes the 270°-output signal output unit thereof, the signal output unit
143
b
constitutes the 90°-output signal output unit thereof, and also the signal output unit
143
c
constitutes the 180°-output signal output unit thereof. As a result, the 0°-output signal output unit, the 90°-output signal unit, the 180°-output signal unit, and the 270°-output signal unit are sequentially arranged at the positions on the circle “β” separated by the phase angle of 90 degrees. This circle “β” is located as a center of the board edge portion
110
c
of the board
110
along the width “H” direction thereof.
In this case, a first phase adjusting circuit is arranged by the hybrid circuit
141
, the balun circuit
142
, and the 50 Ω-signal line
150
. A second phase adjusting circuit is arranged by the 50 Ω-signal line
147
, the balun circuit
143
, and the 50 Ω-signal line
151
. The board edge portion
110
c
formed on one plane
110
a
of the board
110
constitutes a first arranging unit where the signal output units
142
b
and
142
c
are arranged.
The board edge portion
110
c
formed on the other plane
110
b
of the board
110
constitutes a second arranging unit where the signal output units
143
b
and
143
c
are arranged. These first arranging unit and second arranging unit will constitute an arranging unit.
Although the invention has been described in detail in its most preferred embodiments, the combination and array of parts for its preferred embodiments can be modified in various manners without departing from the spirit and scope thereof, as claimed in the following.
Claims
- 1. A helical antenna comprising:a plurality of antenna elements, each of which antenna elements having a signal input unit for an electric power feeding signal; feeding means having at least plural signal output units corresponding to the number of said signal input units, for outputting the feeding signals from the respective signal output units while giving a predetermined phase difference to said feeding signals; a first holding mechanism for holding the respective signal input units of said antenna elements on the substantially same circumference, said first holding mechanism is constructed of a tube body, an adjoining portion of which is located within a plane, said adjoining portion containing an edge plane of said tube body, and the respective signal input units of said antenna elements are held at said adjoining portion of said tube body; a second holding mechanism for holding the respective signal output units of said feeding means on a line which is located perpendicular to said plane where said circumference is positioned, and also which passes through an essential center of said circumference; and a plurality of feeding lines for connecting the respective signal input units of the respective antenna elements to the respective signal output units of said feeding means with maintaining the individual relationship among them; said feeding means includes a circuit board; and a feeding circuit mounted on said circuit board, and having the respective signal output units, for processing said feeding signals to output the processed feeding signals from the respective signal output units, while applying a predetermined phase difference to the processed feeding signals; said circuit board contains an arranging unit where the respective signal output units are arranged; said circuit board is held by said tube body in such a manner that said arranging unit is located within a plane which is positioned in parallel to such a plane involving a plane which passing through said edge plane of the tube body; and the stacked layer board is held by the tube body with a planar direction of the board being parallel to a direction of the axial center of the tube body.
- 2. The helical antenna as claimed in claim 1 wherein:said tube is a cylindrical body.
- 3. The helical antenna as claimed in claim 1 wherein:said plurality of antenna elements are four elements; and said feeding circuit adjusts the phases of the respective feeding signals so as to have phase differences by essentially 90 degrees, thereafter outputs the phase-adjusted feeding signals from the respective output terminals.
- 4. The helical antenna as claimed in claim 3 wherein:said feeding circuit includes: a first phase adjusting circuit provided on one plane of said circuit board, for delaying the phases of said feeding signals at phase angles of essentially 0°/90°/180°; and a second phase adjusting circuit provided on the other plane of said circuit board, for delaying the 90°-delayed phase of the feeding signal outputted from said first phase adjusting circuit at phase angles of essentially 0°/180°; said arranging unit contains: a first arranging unit provided on said one plane of said circuit board in correspondence with said first phase adjusting circuit; and a second arranging unit provided on said other plane of said circuit board in correspondence with said second phase adjusting circuit.
- 5. The helical antenna as claimed in claim 1 wherein:said feeding means is further comprised of an impedance matching circuit.
- 6. The helical antenna as claimed in claim 1 wherein:said feeding line is constructed of an electric wire.
- 7. The helical antenna as claimed in claim 1 wherein:said feeding line is constructed of a wiring pattern formed on a board.
- 8. The helical antenna as claimed in claim 1 wherein:the stacked layer board is disposed in the interior of the tube body.
- 9. The helical antenna as claimed in claim 1, wherein:the stacked layer board is held within the cylindrical body in such a manner that an edge portion of this stacked layer board is located within a plane which passes through the edge of the cylindrical body.
- 10. A helical antenna comprising:a plurality of antenna elements, each of which antenna elements having a signal input unit for an electric power feeding signal; feeding means having at least plural signal output units corresponding to the number of said signal input units, for outputting the feeding signals from the respective signal output units while giving a predetermined phase difference to said feeding signals; a first holding mechanism for holding the respective signal input units of said antenna elements on the substantially same circumference in an equi-interval along a circumferential direction thereof, said first holding mechanism is constructed of a tube body, an adjoining portion of which is located within a plane, said adjoining portion containing an edge plane of said tube body, and the respective signal input units of said antenna elements are held at said adjoining portion of said tube body; a second holding mechanism for holding the respective signal output units of said feeding means on an another circumference in an equi-interval along a circumferential direction thereof, said another circumference being provided in a plane which is parallel to the plane of said circumference, or on the same plane as said circumference, while setting as a center one point on a line which is located perpendicular to a plane where said circumference is positioned, and also which passes through an essential center of said circumference; and a plurality of feeding lines for connecting the respective signal input units of the respective antenna elements to the respective signal output units of said feeding means with maintaining the individual relationship among them; said feeding means include a circuit board; and a feeding circuit mounted on said circuit board, and having the respective signal output units, for processing said feeding signals to output the processed feeding signals from the respective signal output signal, while applying a predetermined phase difference to the processed feeding signals; said circuit board contains an arranging unit where the respective signal output units are arranged; said circuit board is held by said tube body in such a manner that said arranging unit is located within a plane which is positioned in parallel to such a plane involving a plane which passes through said edge plane of the tube body; and the stacked layer board is held by the tube body with a planar direction of the board being parallel to a direction of the axial center of the tube body.
- 11. A helical antenna as claimed in claim 10 wherein:said second holding mechanism holds said signal output units at the same phase angle positions as said signal input units.
- 12. The helical antenna as claimed in claim 10 wherein:said tube is a cylindrical body.
- 13. The helical antenna as claimed in claim 10 wherein:said plurality of antenna elements are four elements; and said feeding circuit adjusts the phases of the respective feeding signals so as to have phase differences by essentially 90 degrees, thereafter outputs the phase-adjusted feeding signals from the respective output terminals.
- 14. The helical antenna as claimed in claim 13 wherein:said feeding circuit includes: a first phase adjusting circuit provided on one plane of said circuit board, for delaying the phases of said feeding signals at phase angles of essentially 0°/90°/180°; and a second phase adjusting circuit provided on the other plane of said circuit board, for delaying the 180°-delayed phase of the feeding signal outputted from said first phase adjusting circuit at phase angles of essentially 0°/90°; said arranging unit contains: a first arranging unit provided on said one plane of said circuit board in correspondence with said first phase adjusting circuit; and a second arranging unit provided on said other plane of said circuit board in correspondence with said second phase adjusting circuit.
- 15. The helical antenna as claimed in claim 10 wherein:the stacked layer board is disposed in the interior of the tube body.
- 16. The helical antenna as claimed in claim 10, wherein:the stacked layer board is held within the cylindrical body in such a manner that an edge portion of this stacked layer board is located within a plane which passes through the edge of the cylindrical body.
Priority Claims (2)
| Number |
Date |
Country |
Kind |
| 10-287697 |
Oct 1998 |
JP |
|
| 11-275666 |
Sep 1999 |
JP |
|
US Referenced Citations (3)
