Antenna device and portable terminal

TECHNICAL FIELD

The present invention relates to an antenna device and a mobile terminal and more particularly to an antenna device contained in a mobile phone and a mobile phone using the antenna device.

BACKGROUND ART

Antennas contained in housings of mobile phones are conventionally known as receiving/transmitting antennas for the mobile phones.

These antennas are classified into linear antennas and plate antennas depending on their characteristics.

FIG. 20

is a schematic plan view of a mobile phone containing a dipole antenna that is one of conventional linear antennas. Referring to

FIG. 20

, a conventional mobile phone

1

x

has a housing

10

and an antenna device

3

x

accommodated in housing

10

. Antenna device

3

x

has a substrate

11

and a dipole antenna

121

provided on substrate

11

. Dipole antenna

121

has two meander-like antenna portions

121

a

and

121

b

respectively connected to a feed point

12

. The electrical length of dipole antenna

121

is λ/2.

During a call, the direction in which such a dipole antenna

121

extends (the direction indicated by an arrow

125

) is approximately at a 30° angle with respect to a vertical direction. Therefore, dipole antenna

121

is known as an antenna which allows for reduction of polarization loss for a wave polarized vertically to the ground (a vertically polarized wave) at the time of a call.

FIG. 21

is a diagram showing a radiation pattern of the conventional dipole antenna shown in FIG.

20

. As shown in

FIG. 21

, when mobile phone

1

x

is placed upright, particularly when the electrical length of the antenna is λ/2×A (A is an integer), a null point

134

of the radiation pattern as indicated by solid lines

131

and

132

is in a horizontal plane. This disadvantageously reduces the gain.

FIG. 22

is a graph showing the relation between the electrical length of the antenna and the current distribution on the antenna element in the conventional dipole antenna. As shown in

FIG. 22

, in the dipole antenna having an electrical length of λ/2, the maximum value of the current distribution exists at the portion where the electrical length of the antenna is λ/4, that is, at the central portion of the antenna. As a hand easily touches this portion, an antenna gain degrades particularly when a hand touches it.

FIG. 23

is a plan view of a mobile phone having a conventional plate antenna. Referring to

FIG. 23

, a mobile phone

1

y

has a housing

10

and an antenna device

3

y

accommodated in housing

10

. Antenna device

3

y

has a substrate

11

and a plate antenna

122

provided on substrate

11

. Plate antenna

122

is connected to a feed point

12

.

Such a plate antenna

122

easily receives and transmits both a vertically polarized wave and a horizontally polarized wave with respect to the ground. Advantageously, degradation amount of gains when a finger touches the antenna is small as compared with a linear antenna, since the current in the vicinity of the feed point is dispersed.

Plate antenna

122

, however, for example a patch antenna, requires about λ as the total perimeter of the antenna, the size of the antenna inevitably increases and thus mobile phone

1

y

itself increases in size.

The present invention is therefore made to solve the above problems. An object of the present invention is to provide an antenna device capable of receiving and transmitting both a vertically polarized wave and a horizontally polarized wave, being reduced in size and having small gain degradation during a call.

DISCLOSURE OF THE INVENTION

An antenna device in accordance with the present invention includes a substrate and an antenna provided on the substrate and having an electrical length of approximately (λ/2)×A (A is an integer). The antenna includes a plate antenna portion positioned at a portion where an electrical length from an end portion is approximately λ/4+(λ/2)×B (B is an integer), and a linear antenna portion connected to the plate antenna.

In the antenna device thus configured, the linear antenna portion can mainly receive and transmit either one of a vertically polarized wave or a horizontally polarized wave, and the plate antenna portion can receive and transmit both the vertically polarized wave and the horizontally polarized wave. As a result, both the vertically polarized wave and the horizontally polarized wave can be received and transmitted, resulting in a high gain antenna.

Furthermore, since the electrical length of the antenna is approximately (λ/2)×A (A is an integer), the current is large at the portion where the electrical length from the end portion of the antenna is approximately λ/4+(λ/2)×B (B is an integer). However, this portion is provided with the plate antenna portion and therefore the current can be distributed. Accordingly, even when a finger is placed on this portion, degradation in gain can be reduced.

Furthermore, since the antenna includes the linear antenna portion, the antenna can be reduced in size as compared with an antenna configured only with a plate antenna portion.

More specifically, the present invention can provide an antenna having a high gain even at the time of a call, assuring a gain when the terminal is placed upright, and having a small size.

Preferably, the linear antenna portion includes at least one selected from the group consisting of a monopole antenna, a zigzag antenna, a meander line antenna and a helical antenna.

More preferably, the substrate has a main surface having conductivity. The antenna further includes a connection portion connected to the main surface of the substrate. In this case, since the antenna is connected to the main surface having conductivity, an image is formed on the substrate. As a result, the electrical length of the antenna is approximately double the physical length of the antenna, so that the physical length of the antenna can be shortened. Therefore, the antenna device can be reduced in size.

Preferably, the substrate has a main surface and a side surface continuous with the main surface, and the antenna is provided on the side surface. In this case, since the main surface is not provided with an antenna, other device and the like can be placed on the main surface.

A mobile terminal in accordance with the present invention includes a housing and an antenna device contained in the housing. The antenna device includes a substrate and an antenna provided on the substrate and having an electrical length of approximately (λ/2)×A (A is an integer). The antenna includes a plate antenna portion positioned at a portion where an electrical length from an end portion is approximately λ/4+(λ/2)×B (B is an integer), and a linear antenna portion connected to the plate antenna portion.

In the mobile terminal thus configured, the linear antenna portion can mainly receive and transmit either one of a vertically polarized wave or a horizontally polarized wave and a plate antenna portion can receive and transmit both the horizontally polarized wave and the vertically polarized wave. As a result, both the vertically polarized wave and the horizontally polarized wave can be received and transmitted, resulting in a mobile terminal having a high gain antenna device.

Furthermore, since the electrical length of the antenna is approximately (λ/2)×A (A is an integer), the current is large at the portion where the electrical length from the end portion of the antenna is approximately λ/4+(λ/2)×B (B is an integer). However, since this portion is provided with the plate antenna portion, the current can be dispersed. Therefore, even when a finger or the like is placed on this portion, degradation in gain can be reduced.

Furthermore, the antenna includes the linear antenna portion, and thus the antenna and the mobile terminal can be reduced in size as compared with an antenna configured only with a plate antenna portion.

In addition, since the antenna device is contained in the housing, the antenna device is less affected by a human body. As a result, degradation in gain can be prevented.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1

is a schematic plan view of the mobile phone having the antenna device in accordance with a first embodiment of the present invention.

FIG. 2

is a side view of the mobile phone seen from a direction indicated by an arrow II in FIG.

1

.

FIG. 3

is a graph showing the relation between the electrical length of the antenna and the current in the mobile phone shown in

FIGS. 1 and 2

.

FIG. 4

is a schematic plan view of the mobile phone having the antenna device in accordance with a second embodiment of the present invention.

FIG. 5

is a side view of the mobile phone seen from a direction indicated by an arrow V in FIG.

4

.

FIG. 6

is a schematic plan view of the mobile phone having the antenna device in accordance with a third embodiment of the present invention.

FIG. 7

is a side view of the mobile phone seen from a direction indicated by an arrow VII in FIG.

6

.

FIG. 8

is a schematic plan view of the mobile phone having the antenna device in accordance with a fourth embodiment of the present invention.

FIG. 9

is a side view of the mobile phone seen from a direction indicated by an arrow IX in FIG.

8

.

FIG. 10

is a schematic plate view of the mobile phone having the antenna device in accordance with a fifth embodiment of the present invention.

FIG. 11

is a side view of the mobile phone seen from a direction indicated by an arrow XI in FIG.

10

.

FIG. 12

is a schematic plan view of the mobile phone having the antenna device in accordance with a sixth embodiment of the present invention.

FIG. 13

is a side view of the mobile phone seen from a direction indicated by an arrow XIII in FIG.

12

.

FIG. 14

shows the step of measuring a radiation pattern in Y-Z plane.

FIG. 15

shows the step of measuring a radiation pattern in Y-Z plane.

FIG. 16

shows the step of measuring a radiation pattern in Y-Z plane.

FIG. 17

is a graph showing a radiation pattern in Y-Z plane in the product of the present invention.

FIG. 18

is a graph showing a radiation pattern in Y-Z plane for a conventional mobile phone shown in FIG.

20

.

FIG. 19

is a graph showing a radiation pattern in Y-Z plane for a conventional mobile phone shown in FIG.

23

.

FIG. 20

is a schematic plan view of the mobile phone containing a conventional dipole antenna.

FIG. 21

shows a radiation pattern of the mobile phone shown in FIG.

20

.

FIG. 22

is a graph showing the relation between the electrical length of the antenna shown in FIG.

20

and the current distribution on the antenna element.

FIG. 23

is a schematic plan view of the mobile phone having a conventional plate antenna.

BEST MODE FOR CARRYING OUT THE INVENTION

In the followings, embodiments of the present invention will be described with reference to the figures.

(First Embodiment)

FIG. 1

is a schematic plan view of a mobile phone having an antenna device in accordance with a first embodiment of the present invention.

FIG. 2

is a side view of the mobile phone seen from a direction indicated by an arrow II in FIG.

1

. Referring to

FIGS. 1 and 2

, mobile phone

1

a

has a housing

10

and an antenna device

3

a

contained in housing

10

. Antenna device

3

a

includes a substrate

11

and an antenna

21

provided on substrate

11

and having an electrical length of (λ/2)×A (A is an integer). Antenna

21

has a plate antenna

21

b

as a plate antenna portion positioned at a portion where an electrical length from an end portion

21

d

is approximately λ/4+(λ/2)×B (B is an integer), and meander line antennas

21

a

and

21

c

as a linear antenna portion connected to plate antenna

21

b.

Substrate

11

is formed by depositing a high conductive metal such as copper on a prescribed insulating substrate. It is noted that the metal formed on the insulating substrate can be replaced by one having the same level of conductivity as copper. Substrate

11

extends in a longitudinal direction and has a rectangular shape. Antenna

21

is provided to extend along the short side of substrate

11

.

Antenna

21

has plate antenna

21

b

as a plate antenna portion positioned at the central portion and meander line antennas

21

a

and

21

c

as a linear antenna portion positioned at opposing ends thereof. Plate antenna

21

b

is connected to feed point

12

. Both meander line antennas

21

a

and

21

c

and plate antenna

21

b

are provided on a main surface

11

a

of substrate

11

as opposed to main surface

11

a.

Plate antenna

21

b

is connected to a radio unit, not shown, through feed point

12

. When a person is making a call with mobile phone

1

a

on the ear, the direction in which antenna

21

extends is approximately at 30° (a zenith angle 30°) with respect to a vertical direction. Antenna

21

is contained in housing

10

.

FIG. 3

is a graph showing the relation between the electrical length of the antenna and the current in mobile phone

1

a

shown in

FIGS. 1 and 2

. Referring to

FIG. 3

, regions

221

a

and

221

c

correspond to regions where meander line antennas

21

a

and

21

c

exist, while region

221

b

corresponds to a region where plate antenna

21

b

exists. As shown in

FIG. 3

, it is understood that provision of plate antenna

21

b

in region

221

b

where the current becomes larger can prevent the current value increase in this portion.

In mobile phone

1

a

and antenna device

3

a

thus configured, first, meander line antennas

21

a

and

21

c

receive and transmit either a vertically or horizontally polarized wave and plate antenna

21

b

receives and transmits both the vertically and horizontally polarized waves. As a result, both the vertically and horizontally polarized waves can be received and transmitted, thereby preventing degradation in gain. Furthermore, as shown in

FIG. 3

, it is possible to decrease the current value at the central portion of the antenna, so that degradation in gain can be prevented even when this portion is touched by a finger or the like.

In addition, antenna

21

is contained in housing

10

, so that antenna

21

is not in direct contact with a human body. As a result, antenna

21

is less affected by a human body and therefore degradation in gain due to a human body can be prevented.

(Second Embodiment)

FIG. 4

is a schematic plan view of the mobile phone having the antenna device in accordance with a second embodiment of the present invention.

FIG. 5

is a side view of the mobile phone seen from a direction indicated by an arrow V in FIG.

4

. Referring to

FIGS. 4 and 5

, a mobile phone

1

b

and an antenna device

3

b

in accordance with the second embodiment of the present invention differs from antenna device

3

a

illustrated in the first embodiment in that antenna

21

is provided on a zenith plane

11

b

as a side surface of substrate

11

. Antenna

21

is connected to feed point

12

.

First, antenna device

3

b

and mobile phone

1

b

thus configured has an effect similar to that of antenna device

3

a

and mobile phone

1

b

illustrated in the first embodiment. In addition, since antenna

21

is provided on zenith plane

11

b,

an area available on main surface

11

a

is increased as compared with antenna

21

provided on main surface

11

a.

As a result, other components can be placed on main surface

11

a.

(Third Embodiment)

FIG. 6

is a schematic plan view of the mobile phone having the antenna device in accordance with a third embodiment of the present invention.

FIG. 7

is a side view of the mobile phone seen from a direction indicated by an arrow VII in FIG.

6

. Referring to

FIGS. 6 and 7

, a mobile phone

1

c

and an antenna device

3

c

in accordance with the third embodiment of the present invention differs from mobile phone

1

a

and antenna device

3

a

illustrated in the first embodiment in that a linear antenna portion of an antenna

23

is configured with helical antennas

23

a

and

23

c.

Helical antennas

23

a

and

23

c

are configured in a helical manner and has one end connected to plate antenna

21

b.

Helical antennas

23

a

and

23

c

are provided in a spiral manner and are not in direct contact with substrate

11

.

Mobile phone

1

c

has housing

10

and antenna device

3

c

contained in housing

10

. Antenna device

3

c

includes substrate

11

and antenna

23

provided on substrate

11

and having an electrical length of (λ/2)×A (A is an integer). Antenna

23

has plate antenna

21

b

as a plate antenna portion positioned at a portion where an electrical length from an end portion

23

d

is approximately λ/4+(λ/2)×B (B is an integer), and helical antennas

23

a

and

23

c

as a linear antenna portion connected to plate antenna

21

b.

Antenna device

3

c

and mobile phone

1

c

thus configured has an effect similar to that of antenna device

3

a

and mobile phone

1

c

illustrated in the first embodiment.

(Fourth Embodiment)

FIG. 8

is a schematic plan view of the mobile phone having the antenna device in accordance with a fourth embodiment of the present invention.

FIG. 9

is a side view of the mobile phone seen from a direction indicated by an arrow IX in FIG.

8

. Referring to

FIGS. 8 and 9

, an antenna device

3

d

in accordance with the fourth embodiment of the present invention differs from antenna

21

illustrated in the first embodiment in that an antenna

24

is configured with zigzag antennas

24

a

and

24

c

and plate antenna

21

b.

More specifically, mobile phone

1

d

has housing

10

and antenna device

3

d

contained in housing

10

. Antenna device

3

d

includes substrate

11

and antenna

24

provided on substrate

11

and having an electrical length of (λ/2)×A (A is an integer). Antenna

24

has plate antenna

21

b

as a plate antenna portion positioned at a portion where an electrical length from an end portion

24

d

is approximately λ/4+(λ/2)×B (B is an integer), and zigzag antennas

24

a

and

24

c

as a linear antenna portion connected to plate antenna

21

b.

Antenna device

3

d

and mobile phone

1

d

thus configured also has an effect similar to that of antenna device

3

a

and mobile phone

1

a

illustrated in the first embodiment.

(Fifth Embodiment)

FIG. 10

is a plan view of the mobile phone having the antenna device in accordance with a fifth embodiment of the present invention.

FIG. 11

is a side view of the mobile phone seen from a direction indicated by an arrow XI in FIG.

10

.

Referring to

FIGS. 10 and 11

, a mobile phone

1

e

has housing

10

and an antenna device

3

e

contained in housing

10

. Antenna device

3

e

includes substrate

11

and an antenna

25

provided on substrate

11

and having an electrical length of (λ/2)×A (A is an integer). Antenna

25

has a connection portion

25

a

as a plate antenna portion positioned at a portion where an electrical length from an end portion

25

d

is approximately λ/4+(λ/2)×B (B is an integer), a plate antenna

25

b

and a zigzag antenna

25

c

as a linear antenna portion connected to connection portion

25

a

through plate antenna

25

b.

Antenna

25

is provided on main surface

11

a

of substrate

11

. Antenna

25

has connection portion

25

a

connected to main surface

11

a,

plate antenna

25

b

connected to connection portion

25

a,

and zigzag antenna

25

c

connected to plate antenna

25

b.

Connection portion

25

a

is formed of a plate antenna and connects main surface

11

a

having conductivity to plate antenna

25

b.

Connection portion

25

a

is also connected to feed point

12

. Plate antenna

25

b

is provided as opposed to main surface

11

a

and has one end connected to connection portion

25

a

and the other end connected to zigzag antenna

25

c.

Since connection portion

25

a

is connected to main surface

11

a

having conductivity, an image of the antenna is formed also on main surface

11

a.

Therefore, although the physical length of antenna

25

is (λ/4)×A (A is an integer), the electrical length is (λ/2)×A (A is an integer).

First, antenna device

3

e

and mobile phone

1

e

thus configured has an effect similar to that of antenna device

3

a

and mobile phone

1

a

illustrated in the first embodiment. In addition, antenna device

3

e

and mobile phone

1

e

can be reduced in size, since the physical length of antenna

25

is reduced.

It is noted that although plate antenna

25

b

is connected with zigzag antenna

25

c

in this embodiment, plate antenna

25

b

may be connected with a monopole antenna, a meander line antenna and a helical antenna.

(Sixth Embodiment)

FIG. 12

is a plan view of the mobile phone having the antenna device in accordance with a sixth embodiment of the present invention.

FIG. 13

is a side view of the mobile phone seen from a direction indicated by an arrow XIII in FIG.

12

. Referring to

FIGS. 12 and 13

, a mobile phone

1

f

has housing

10

and an antenna device

3

f

contained in housing

10

. Antenna device

3

f

includes substrate

11

and an antenna

26

provided on substrate

11

and having an electrical length of (λ/2)×A (A is an integer). Antenna

26

has a plate antenna

26

c

as a plate portion positioned at a portion where an electrical length from an end portion

26

e

is approximately λ/4+(λ/2)×B (B is an integer), meander line antennas

26

a

and

26

d

as a linear antenna portion connected to plate antenna

26

c,

and a connection portion

26

b.

Plate antenna

26

c

is connected to feed point

12

and also to connection portion

26

b.

Connection portion

26

b

connects plate antenna

26

c

to main surface

11

a

having conductivity. Both meander line antennas

26

a

and

26

d

and plate antenna

26

c

are provided as opposed to main surface

11

a.

Antenna

26

is connected to main surface

11

a

at connection portion

26

b.

Therefore, an image of antenna

26

is formed on main surface

11

a.

Although the physical length of antenna

26

is (λ/4)×A (A is an integer), the electrical length is (λ/2)×A (A is an integer). Plate antenna

26

c

is provided at the central portion of antenna

26

, specifically at a portion where the current value is maximized in antenna

26

.

Antenna device

3

f

and mobile phone

1

f

thus configured also has an effect similar to that of antenna device

3

e

and mobile phone

1

e

illustrated in the fifth embodiment.

Now, the specific effect of the present invention will be described.

FIGS. 14

to

16

show the steps of measuring radiation patterns in Y-Z plane. Referring to

FIG. 14

, mobile phone

1

a

(

FIG. 1

) illustrated in the first embodiment was first prepared. The electrical length of antenna

21

was λ/2. Plate antenna

21

b

was arranged at a position where the electrical length is λ/4 from the end portion

21

d

of the antenna. Here, mobile phone

1

a

was placed on a table

150

such that a Y direction (a direction in which the shorter side of substrate

11

extends) and a Z direction (a direction in which the longer side of substrate

11

extends), as shown in

FIG. 1

, were on a horizontal plane. Furthermore, X direction was in a vertical direction indicated by an arrow

140

. Table

150

was rotatable in a direction indicated by arrow R.

With mobile phone

1

a

being placed on table

150

in this manner, a radio wave at a frequency of 1.95 GHz was radiated at a prescribed power from the radio transceiver unit on substrate

11

through antenna device

3

a.

Then, table

150

was rotated in the direction indicated by arrow R. Accordingly, antenna device

3

a

radiated a radio wave as indicated by an arrow

151

. The field intensity of this radio wave was measured by an measuring antenna

160

and the field intensity was found for a vertically polarized wave in a direction indicated by an arrow V and a horizontally polarized wave in a direction indicated by an arrow H for this radio wave.

Referring to

FIG. 15

, a dipole antenna

170

was placed on table

150

. Dipole antenna

170

is provided with a feed point

171

at the central portion, and feed point

171

is connected to a coaxial cable

172

. Coaxial cable

172

is connected to a prescribed radio transceiver unit. Dipole antenna

170

extends approximately parallel to the vertical direction indicated by an arrow

140

. With table

150

being rotated in a direction indicated by arrow R, similar power as provided by the radio transceiver unit to antenna

3

a

shown in

FIG. 14

was provided to dipole antenna

170

so that a radio wave at a frequency of 1.95 GHz as indicated by an arrow

152

was radiated from dipole antenna

170

. Accordingly, the radio wave indicated by arrow

152

was radiated from dipole antenna

170

. This radio wave is a vertically polarized wave in a direction shown by arrow V. The field intensity of this radio wave was measured by measuring antenna

160

.

Referring to

FIG. 16

, similar power as provided by the radio transceiver unit to antenna device

3

a

was provided to dipole antenna

170

so that a radio wave at a frequency of 1.95 GHz as indicated by arrow

153

was radiated from dipole antenna

170

. This radio wave is a horizontally polarized wave in a direction indicated by an arrow H. The field intensity of this radio wave was obtained by measuring antenna

160

.

The radiation pattern of the antenna device in accordance with the present invention was obtained based on data obtained form the steps shown in

FIGS. 14-16

. The result is shown in FIG.

17

.

In

FIG. 17

, a solid line

301

shows the gain of the vertically polarized wave component of the radio wave radiated from antenna device

3

a

shown in

FIG. 14

, with respect to the field intensity of the vertically polarized wave radiated from dipole antenna

170

in the step shown in FIG.

15

. This gain was calculated according to the following formula.

(gain)=20×log

10

(the field intensity of the vertically polarized wave from antenna device

3

a

/the field intensity of the vertically polarized wave from dipole antenna

170

)

A dotted line

302

shows the gain of the horizontally polarized wave component of the radio wave radiated from antenna device

3

a

shown in

FIG. 14

, with respect to the field intensity of the horizontally polarized wave radiated from dipole antenna

170

in the step shown in FIG.

16

. This gain was calculated according to the following formula.

(gain)=20×log

10

(the field intensity of the horizontally polarized wave from antenna device

3

a

/the field intensity of the horizontally polarized wave from dipole antenna

170

)

As seen from

FIG. 17

, in antenna device

3

a

in accordance with the present invention, the gain of the vertically polarized wave is relatively uniform in all directions. Furthermore, the gain of the horizontally polarized wave is also generally uniform in all directions. Therefore, it is appreciated that various polarized waves can be received and transmitted.

Next, mobile phone

1

x

having the conventional antenna device

3

x

shown in

FIG. 20

was used and placed on table

150

with Y-axis and X-axis oriented in the horizontal direction and with X-axis parallel to the vertical direction in accordance with the step shown in FIG.

14

. In this state, with table

150

being rotated in the direction indicated by arrow R, a radio wave at a frequency of 1.95 GHz was radiated through antenna device

3

x.

At this point, similar power as provided by the radio transceiver unit to antenna device

3

a

was provided to antenna device

3

x.

The vertically polarized wave component and the horizontally polarized wave component of this radiated radio wave were measured by measuring antenna

160

. The radiation pattern for such a conventional antenna is shown in FIG.

18

. In

FIG. 18

, a solid line

311

shows the gain of the field intensity of the vertically polarized wave component of the radio wave radiated from antenna device

3

x

in accordance with the step shown in

FIG. 14

, with respect to the field intensity of the vertically polarized wave measured in the step shown in FIG.

15

. This gain was calculated according to the following formula.

(gain)=20×log

10

(the field intensity of the vertically polarized wave from antenna device

3

x

/the field intensity of the vertically polarized wave from dipole antenna

170

)

A dotted line

312

shows the gain of the field intensity of the horizontally polarized wave component of the radio wave radiated from antenna device

3

x

in accordance with the step shown in

FIG. 14

, with respect to the field intensity of the horizontally polarized wave measured in the step shown in FIG.

16

. This gain was calculated according to the following formula.

(gain)=20×log

10

(the field intensity of the horizontally polarized wave from antenna device

3

x

/the field intensity of the horizontally polarized wave from dipole antenna

170

)

As seen from

FIG. 18

, the gain of the vertically polarized wave is extremely small in the Y-axis direction in the conventional one.

Then, mobile phone

1

y

having the conventional antenna device

3

y

shown in

FIG. 23

was used and placed on table

150

with Y-axis and Z-axis oriented in the horizontal direction and with X-axis in parallel to the vertical direction in accordance with the similar step as shown in FIG.

14

. In this state, with table

150

being rotated in the direction indicated by arrow R, a radio wave at a frequency of 1.95 GHz was radiated through antenna device

3

y.

At this point, similar power as provided by the radio transceiver unit to antenna device

3

a

was provided to antenna device

3

y.

The vertically polarized wave component and the horizontally polarized wave component of this radiated radio wave were measured by measuring antenna

160

. The radiation pattern for such a conventional antenna is shown in FIG.

19

. In

FIG. 19

, a solid line

321

shows the gain of the field intensity of the vertically polarized wave component of the radio wave radiated from antenna device

3

y

in accordance with the step shown in

FIG. 14

, with respect to the field intensity of the vertically polarized wave measured in the step shown in FIG.

15

. This gain was calculated according to the following formula.

(gain)=20×log

10

(the field intensity of the vertically polarized wave from antenna device

3

y

/the field intensity of the vertically polarized wave from dipole antenna

170

)

A dotted line

322

shows the gain of the field intensity of the horizontally polarized wave component of the radio wave radiated from antenna device

3

y

in accordance with the step shown in

FIG. 14

, with respect to the field intensity of the horizontally polarized wave measured in the step shown in FIG.

16

. This gain was calculated according to the following formula.

(gain)=20×log

10

(the field intensity of the horizontally polarized wave from antenna device

3

y

/the field intensity of the horizontally polarized wave from dipole antenna

170

)

As seen from

FIG. 18

, when the plate antenna is used, radio waves can be received and transmitted relatively from every direction.

This plate antenna

122

, however, has a problem in that the total perimeter of the antenna is λ and the mobile phone is increased in size.

Then, the gains were measured when a person made a call holding the aforementioned mobile phones

1

a,

1

x

and

1

y

at either the right or left hand. Here, given that the gain was 0 dB when the person made a call holding mobile phone

1

a

at the left hand, the gains were measured respectively for the samples held at either the left hand or the right hand. The result is shown in Table 1.

TABLE 1

gains during call

sample

held at the left hand

held at the right hand

1a

0

−0.03

1x

−2.63

−0.09

1y

−3.84

+0.72

As seen from Table 1, in mobile phone

1

a

of the present invention, gain variations are small whether the mobile phone is held at the right or left hand. On the contrary, it can be observed that in mobile phone

1

x,

the gain is decreased compared with the present invention product when it is held at either the right hand or the left hand. Furthermore, in mobile phone

1

y,

the gain is increased compared with the present invention when it is held at the right hand, whereas the gain is significantly degraded when it is held at the left hand. Therefore, the gain variations are large. Accordingly, it is appreciated that in the present invention the gain variations are reduced whether the mobile phone is held at the right or left hand.

Furthermore, the maximum field intensity was obtained in the vicinity of the antenna for each of mobile phones

1

a,

1

x

and

1

y.

Given that the maximum field intensity in mobile phone

1

a

was 100%, the field intensity in mobile phone

1

x

was 130% and the maximum field intensity in mobile phone

1

y

was 68%. Therefore, even when a person touches the vicinity of the antenna, the electric field is less affected by the action of the person, because concentration of the electric field is relieved in the present invention as compared with mobile phone

1

x.

As a result, decrease in gain can be prevented.

It is noted that a monopole antenna can be used as a linear antenna in all the embodiments described above. In order to reduce the mobile phone in size, it is preferable that the electrical length of antennas

21

,

23

,

24

is λ/2 in the first to fourth embodiments.

INDUSTRIAL APPLICABILITY

The antenna device and the mobile phone in accordance with the present invention can be utilized in the field of mobile phones containing antennas.

Number	Name	Date	Kind
6225951	Holshouser et al.	May 2001	B1
6337663	Chi-Ming	Jan 2002	B1
6337667	Ayala et al.	Jan 2002	B1
6346916	Odachi et al.	Feb 2002	B1
6417816	Sadler et al.	Jul 2002	B2
6456250	Ying et al.	Sep 2002	B1
6459413	Tseng et al.	Oct 2002	B1
6559803	Shinichi	May 2003	B2

Number	Date	Country
000924797	Jun 1999	EP
0576181982	Apr 1982	JP
06-318814	Nov 1994	JP
10-303637	Nov 1998	JP
11-274828	Oct 1999	JP

Antenna device and portable terminal

Information

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Date Filed

Date Issued

Inventors

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Agents

CPC

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Abstract

Description

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US Referenced Citations (8)

Foreign Referenced Citations (5)