JP2008060899A - ANTENNA DEVICE AND ELECTRONIC DEVICE USING THE SAME - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the radiation efficiency of an antenna device. <P>SOLUTION: The antenna device 9 has ground-forming bodies 10 formed in an approximately symmetric shape to an arbitrary line or surface, a feeding part 11 formed to the ground-forming body 10, a feeding element 12 connected to the feeding part 11, and a parasitic element 13 connected to the ground-forming body 10 for attaining the object. The feeding element 12 and the parasitic element 13 have a constitution in which both elements are formed in the approximately symmetric shape to the arbitrary line or surface. Since the phase difference of a current flowing through the feeding element 12 and the current flowing through the parasitic element 13 is reduced according to the constitution, the phase difference is decreased in the current flowing through the feeding element 12 and the current interlocked with the current flowing through the parasitic element 13 in the ground-forming bodies 10. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an antenna device that wirelessly transmits a signal and an electronic device in which the antenna device is mounted.

  Some conventional antenna devices use a parasitic element for the purpose of widening the bandwidth. A conventional antenna apparatus using such a parasitic element is shown in FIG.

  In FIG. 8, the conventional antenna device 1 includes a ground forming body 3 that is substantially line-symmetrical with respect to an arbitrary line 2 as an axis of symmetry, a power feeding unit 4 formed on the ground forming body 3, and a power feeding unit 4. It had a connected feeding element 5 and a parasitic element 6 connected to the ground forming body 3. The power feeding unit 4 is connected to a wireless circuit (not shown).

  In the above configuration, when the feeding element 5 and the parasitic element 6 are electromagnetically coupled, the antenna device 1 can transmit or receive a signal in the resonance frequency band of the parasitic element 6, thereby increasing the bandwidth. To do.

  In this conventional antenna device 1, when a current that contributes to radiation flows through the feed element 5 and the parasitic element 6, both elements perform an unbalanced operation, and a current that contributes to radiation also flows through the ground formation body 3. More specifically, the current 7 flows in conjunction with the current flowing through the power feeding element 5 along the peripheral edge of the ground forming body 3 on the power feeding section 4 side, and the non-feeding power along the peripheral edge on the parasitic element 6 side. A current 8 flows in conjunction with the current flowing through the element 6.

As prior art document information related to the invention of this application, for example, Patent Document 1 is known.
JP 2005-5883 A

  In the conventional antenna device 1, the feeding element 5 and the parasitic element 6 are not symmetrical. For this reason, the current 7 linked to the current flowing through the feeding element 5 in the ground forming body 3 and the parasitic element 6 are linked. The phase difference from current 8 was large. That is, the phase difference between the current 7 and the current 8 that flow approximately symmetrically around the peripheral portion of the ground forming body 3 with the arbitrary line 2 as the axis of symmetry was large. As a result, there is a problem that the current 7 and the current 8 cancel each other, and the radiation efficiency of the antenna device 1 deteriorates.

  Therefore, an object of the present invention is to improve the radiation efficiency of an antenna device.

  In order to achieve this object, the antenna device of the present invention includes a ground forming body that is substantially symmetrical with respect to an arbitrary line or surface, a power feeding portion formed on the ground forming body, and a connection to the power feeding portion. The feed element and the parasitic element connected to the ground forming body are substantially symmetrical with respect to an arbitrary line or surface.

  With the above configuration, the phase difference between the current flowing through the feeding element and the current flowing through the parasitic element is reduced, and therefore, the current linked to the current flowing through the feeding element and the current linked to the current flowing through the parasitic element in the ground forming body. The phase difference becomes smaller. That is, the currents that flow substantially symmetrically with respect to an arbitrary line or surface in the peripheral portion of the ground forming body approach the same phase. As a result, the currents flowing symmetrically around the periphery of the ground forming body strengthen each other, and the radiation efficiency of the ground forming body can be improved.

(Embodiment 1)
The first embodiment of the present invention will be described below with reference to FIG. FIG. 1 is a schematic diagram of an antenna device 9 according to Embodiment 1 of the present invention.

  In FIG. 1, an antenna device 9 is connected to the power supply unit 11, a rectangular ground formation body 10 that is substantially line-symmetric with respect to an arbitrary line 14, a power supply unit 11 formed on the ground formation body 10, and the power supply unit 11. And the parasitic element 13 connected to the ground forming body 10. Further, the feeding element 12 and the parasitic element 13 have a substantially line-symmetric shape with an arbitrary line 14 as the axis of symmetry. Note that an electronic device (not shown) using the antenna device 9 has a wireless circuit (not shown) connected to the power feeding unit 11.

  In the above configuration, when the feeding element 12 and the parasitic element 13 are electromagnetically coupled, the antenna device 9 can also transmit or receive a signal in the resonance frequency band of the parasitic element 13, thereby increasing the bandwidth. To do.

  In the antenna device 9, when a current that contributes to radiation flows through the feed element 12 and the parasitic element 13, both elements perform an unbalanced operation, and a current that contributes to radiation also flows through the ground formation body 10. More specifically, the current 15 flows in conjunction with the current flowing through the power feeding element 12 along the peripheral edge of the ground forming body 10 on the power feeding section 11 side, and the non-feeding power along the peripheral edge on the parasitic element 13 side. A current 16 flows in conjunction with the current flowing through the element 13.

  Since the feeding element 12 and the parasitic element 13 have a substantially line-symmetric shape with an arbitrary line 14 as the axis of symmetry, the phase difference between the current flowing through the feeding element 12 and the current flowing through the parasitic element 13 is reduced. For this reason, in the ground forming body 10, the phase difference between the current 15 linked to the current flowing through the feed element 12 and the current 16 linked to the current flowing through the parasitic element 13 becomes small. That is, the currents that flow approximately symmetrically around the peripheral portion of the ground forming body 10 with the arbitrary line 14 as the axis of symmetry approach the same phase. As a result, currents that flow symmetrically around the peripheral portion of the ground forming body 10 with the arbitrary line 14 as an axis strengthen each other, and the radiation efficiency of the ground forming body 10 can be improved.

  Further, with the above configuration, the amplitudes of the currents that flow symmetrically around the peripheral portion of the ground forming body 10 can be made closer to each other. As a result, the radiation efficiency of the ground forming body 10 can be improved.

  The ground forming body 10 may have a substantially plane symmetric shape with an arbitrary plane as a symmetric plane, and the feeding element 12 and the parasitic element 13 may have a substantially plane symmetric shape with an arbitrary plane as a symmetric plane. Also in this case, the phase difference between the current 15 linked to the current flowing through the feed element 12 and the current 16 linked to the current flowing through the parasitic element 13 in the ground forming body 10 becomes small. As a result, currents that flow symmetrically around the peripheral portion of the ground forming body 10 with the arbitrary line 14 as an axis strengthen each other, and the radiation efficiency of the ground forming body 10 can be improved.

  In addition, the ground forming body 10 is substantially rectangular, and it is desirable that the power feeding element 12 and the connecting portion of the ground forming body 10 and the power feeding portion 11 are arranged along the short side of the ground forming body 10. With this configuration, the interval between the currents 15 and 16 that flow symmetrically around the periphery of the ground forming body 10 is narrowed. As a result, the currents 15 and 16 are further strengthened, and the radiation efficiency of the ground forming body 10 can be improved.

  Next, the phase difference between the current 15 and the current 16 that flows symmetrically with respect to an arbitrary line or surface in the peripheral portion of the ground forming body 10 shown in FIG. We measured how the pattern changed by simulation.

  FIG. 3 is a relationship diagram between the phase difference between the current 15 and the current 16, the radiation efficiency (dB) and the radiation pattern in the XY plane of the ground forming body 10 when the operating frequency is 920 MHz, and FIG. FIG. 6 is a relationship diagram between a phase difference between currents 15 and 16 and radiation efficiency (dB) and radiation pattern in the YZ plane of the ground forming body 10 when the frequency is 920 MHz.

  3 and 4, when the phase difference between the current 15 and the current 16 flowing symmetrically with respect to an arbitrary line or surface in the peripheral portion of the ground forming body 10 is within 40 degrees, the radiation efficiency of the ground forming body 10 I understand that is good. In particular, when the phase difference between the current 15 and the current 16 is within 20 degrees, it can be seen that the radiation efficiency of the ground forming body 10 is particularly good.

  Next, in the antenna device 9 shown in FIG. 5, the phase difference between the current 15 and the current 16 that flows symmetrically around the periphery of the ground forming body 10 is changed by changing the distance a between the feed element 12 and the parasitic element 13. How it changes was measured by simulation. In addition, each size in FIG. 5 is b = 40mm c = 75mm d = 8mm e = 7mm. The operating frequency was 920 MHz.

  FIG. 6 is a diagram illustrating the relationship between the interval a and the phase difference between the currents 15 and 16 and the relationship between the interval a and the amplitude ratio between the currents 15 and 16. From FIG. 6, it can be seen that the smaller the distance between the feeding element 12 and the parasitic element 13, the smaller the phase difference between the current 15 and the current 16 flowing symmetrically around the peripheral edge of the ground forming body 10. In particular, when the distance between the feeding element 12 and the parasitic element 13 is 5 mm or less, that is, 0.0153 times or less the wavelength of the current flowing through the feeding element 12 and the parasitic element 13, Can be reduced, and the radiation efficiency of the antenna device 9 can be improved.

  Next, in the antenna device 9 shown in FIG. 7B, the phase difference and the amplitude ratio between the current 15 and the current 16 that flow symmetrically around the periphery of the ground forming body 10 in the antenna device 9 shown in FIG. The phase difference and the amplitude ratio between the current 15 and the current 16 that flow symmetrically around the periphery of the ground forming body 10 were measured by simulation. In addition, the feeding element 12 and the parasitic element 13 in the antenna device 9 shown in FIG. 7A have an outer spiral shape, and the feeding element 12 and the parasitic element 13 in the antenna device 9 shown in FIG. Is the inner spiral shape. The antenna device 9 shown in FIG. 7A and the antenna device 9 shown in FIG. 7B have the same other conditions.

  As a result of the simulation measurement, the phase difference between the current 15 and the current 16 in the antenna device 9 shown in FIG. 7A is smaller than the phase difference between the current 15 and the current 16 in the antenna device 9 shown in FIG. Value. The amplitude ratio between the current 15 and the current 16 in the antenna device 9 shown in FIG. 7A is also smaller than the amplitude ratio between the current 15 and the current 16 in the antenna device 9 shown in FIG. It was. That is, by this simulation measurement, the antenna device 9 in which the feeding element 12 and the parasitic element 13 have an outer spiral shape is compared with an antenna device in which the feeding element 12 and the parasitic element 13 have an inner spiral shape. It can be seen that the radiation efficiency is good.

  As described above, the antenna device of the present invention can improve the radiation efficiency, and is particularly useful for electronic devices such as portable terminals.

Schematic diagram of the antenna device according to the first embodiment of the present invention. The figure for demonstrating the antenna apparatus of Embodiment 1 of this invention The figure for demonstrating the antenna apparatus of Embodiment 1 of this invention The figure for demonstrating the antenna apparatus of Embodiment 1 of this invention Schematic diagram of the antenna device according to the first embodiment of the present invention. The figure for demonstrating the antenna apparatus of Embodiment 1 of this invention (A) (b) is the schematic diagram of the antenna apparatus of Embodiment 1 of this invention. Schematic diagram of a conventional antenna device

Explanation of symbols

DESCRIPTION OF SYMBOLS 9 Antenna apparatus 10 Ground formation body 11 Feeding part 12 Feeding element 13 Parasitic element 14 Arbitrary lines 15,16 Current

Claims (10)

A ground forming body having a substantially line symmetrical shape with an arbitrary line as a symmetry axis;
A power feeding section formed on the ground forming body;
A feed element connected to the feed section;
A parasitic element connected to the ground forming body,
The feeding device and the parasitic element are antenna devices that are substantially line-symmetric with respect to the arbitrary line as an axis of symmetry. A ground forming body having an approximately plane-symmetric shape with an arbitrary plane as a symmetry plane;
A power feeding unit formed on the ground forming body;
A feed element connected to the feed section;
A parasitic element connected to the ground forming body,
The feeding device and the parasitic element are antenna devices having substantially plane symmetry with the arbitrary plane as a symmetry plane. The antenna device according to claim 1, wherein the ground forming body is substantially rectangular. The ground forming body is substantially rectangular,
3. The antenna device according to claim 1, wherein the parasitic element and the connection portion of the ground formation body and the power supply portion are disposed along a short side of the ground formation body. The antenna device according to claim 1 or 2, wherein the feeding element and the parasitic element are spiral, and are wound in opposite directions. The antenna device according to claim 1 or 2, wherein an interval between the feeding element and the parasitic element is 0.153 times or less of a wavelength of a current flowing through the feeding element and the parasitic element. The antenna device according to claim 1, wherein the feeding element and the parasitic element have an outer spiral shape. A ground forming body having a substantially line symmetrical shape with an arbitrary line as a symmetry axis;
A power feeding section formed on the ground forming body;
A feed element connected to the feed section;
A parasitic element connected to the ground forming body,
An antenna device in which a phase difference between currents flowing symmetrically around the peripheral portion of the ground forming body with the arbitrary line as an axis of symmetry is within 40 degrees. A ground forming body having an approximately plane-symmetric shape with an arbitrary plane as a symmetry plane;
A power feeding section formed on the ground forming body;
A feed element connected to the feed section;
A parasitic element connected to the ground forming body,
An antenna device in which a phase difference between currents that flow symmetrically around a peripheral portion of the ground forming body with the arbitrary plane as a symmetry plane is within 40 degrees. An electronic device equipped with the antenna device according to claim 1.

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