JP2006197138A - Multi-frequency sharing antenna device and diversity antenna device constituted of the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multi-frequency sharing antenna device applicable for a system using a plurality of frequency bands. <P>SOLUTION: This antenna device is provided with a base board equipped with a power supply point and a radiating element whose one end is connected to the power supply point, and which is arranged along the periphery of the end of the base board. The radiating element is constituted with length acting as a (2n+1)/4(n is an integer which is n>1) wavelength mono-pole antenna in each operating frequency band. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a multi-frequency shared antenna device suitable for use in a terminal of a mobile communication system, and is applicable to a system using a plurality of broadband frequency bands, and includes a radiating element that can be incorporated in a terminal housing. The present invention relates to a multi-frequency antenna device.

  Many terminal antennas that can be used in a mobile communication system that uses a plurality of frequency bands have a protruding radiating element disposed at the end of a mobile terminal. As shown in FIG. 1, the antenna includes a ground plane 12, a feeding point 14, and a radiating element 16. The radiating element 16 is a monopole antenna radiating element, and is disposed so as to protrude to the outside of the mobile terminal housing indicated by a broken line. Such a portable terminal 10 has poor portability and lacks design. For this reason, a built-in antenna is desired.

  In addition, there is an inverted F antenna as a built-in antenna. As shown in FIG. 2, the antenna includes a ground plane 22, a feeding point 24, and a radiating element 26. The radiating element 26 is an inverted F-shaped antenna radiating element, and is built in the portable terminal housing indicated by a broken line. This antenna has a narrow frequency bandwidth and is difficult to use in a plurality of wide frequency bands. Therefore, a multi-frequency common antenna that can be applied to a mobile communication system using a plurality of broadband frequency bands and can be built in a terminal housing is desired.

  Further, the above-described inverted F antenna is used by being incorporated in a folded portable terminal. As shown in FIG. 3, a folded-shaped mobile terminal often employs a casing having a multi-axis hinge, and the upper casing may be inverted and used. In this case, such an antenna device cannot obtain desired characteristics.

  Of the background art described above, the monopole antenna radiating element and the inverted F antenna are not publicly known as far as the applicant knows at the time of filing.

  Further, the applicant has not been able to find prior art documents related to the present invention by the time of filing. Therefore, prior art document information is not disclosed.

  However, the background art described above has the following problems.

  Since the multi-frequency shared antenna is based on a whip antenna that protrudes outside the portable terminal, there is a problem that portability is poor and design is poor.

  Moreover, since an inverted-F antenna is generally used in one frequency band, there is a problem that it is difficult to configure as a multi-frequency shared antenna.

  Accordingly, an object of the present invention is to solve such problems, and to provide a multi-frequency antenna apparatus applicable to a system using a plurality of frequency bands.

  In order to solve the above problems, an antenna device of the present invention includes a ground plane provided with a feeding point, and a radiating element having one end connected to the feeding point and arranged around the periphery of the ground plane, Each operating frequency band has a length that acts as a (2n + 1) / 4 (n is an integer of n> 1) wavelength monopole antenna.

  By configuring in this way, a multi-frequency antenna device can be realized.

  In addition, another antenna device according to the present invention includes a ground plane provided with a feeding point, and a radiating element having one end connected to the feeding point and arranged around the edge of the ground plane. Is connected to the ground plane and has a length that acts as a (n + 1) / 2 (n is an integer of n> 1) wavelength loop antenna in each operating frequency band.

  By configuring in this way, a multi-frequency antenna device can be realized.

  Further, the diversity antenna device of the present invention, the ground plate provided with the feeding point, one end is connected to the feeding point, the radiating element disposed along the periphery of the ground plate end, and connected to the other end of the radiating element, The radiating element has a length that functions as a (2n + 1) / 4 (n is an integer of n> 1) wavelength monopole antenna in each operating frequency band.

  With this configuration, diversity gain can be improved.

  In addition, another diversity antenna apparatus of the present invention includes two antenna apparatuses described above.

  With this configuration, diversity gain can be improved.

  According to the embodiment of the present invention, it is possible to realize a multi-frequency antenna device applicable to a system using a plurality of frequency bands.

Next, embodiments of the present invention will be described with reference to the drawings.
In all the drawings for explaining the embodiments, the same reference numerals are used for those having the same function, and repeated explanation is omitted.

  An antenna apparatus according to a first embodiment of the present invention will be described with reference to FIG.

  The antenna device 100 according to the present embodiment is an antenna device applied to three frequencies. The antenna device 100 includes a substantially rectangular ground plane 102, a feeding point 104 formed on one main surface of the ground plane 102, and a radiating element 106 having one end connected to the feeding point 104 and arranged along the periphery of the ground plane 102. Prepare. That is, the radiating element 106 is folded back and arranged in parallel to the main surface of the ground plane 102. In FIG. 1, the broken line indicates the casing of the mobile terminal.

  In the present embodiment, the ground plane 102 is substantially rectangular, and a feeding point 104 is provided in a part thereof. The radiating element 106, one end of which is connected to the feeding point 104, is folded back along the periphery of the ground plane 102 while maintaining a distance d from the end of the ground plane 102. Further, the other end portion of the radiating element 106 on the side opposite to the feeding point is not connected to the main plate 102 and is opened. Here, the radiating element 106 has a length that acts as a (2n + 1) / 4 wavelength monopole antenna (n is an integer of n> 1) in each operating frequency band.

  Next, the operation of the antenna device according to the present embodiment will be described with reference to FIG.

In the lowest frequency band f _M1 in the operating frequency, the total length of the radiating element 106 is about 3/4 wavelength, so that a current of 3/4 wavelength is generated and acts as a 3/4 wavelength monopole feeding radiating element.

In the frequency band f _M2 , since the total length of the radiating element 106 is about 5/4 wavelength, a current of 5/4 wavelength is generated and acts as a 5/4 wavelength monopole feeding radiating element.

In the frequency band f _M3 , the total length of the radiating element 106 is about 7/4 wavelength, so that a current of 7/4 wavelength is generated and acts as a 7/4 wavelength monopole feeding radiating element.

  Next, the frequency characteristics of the voltage standing wave ratio at the antenna feeding point of the antenna element according to the present embodiment will be described with reference to FIG.

It can be seen that the antenna device according to this example resonates in five frequency bands f _M1 , f _M2 , f _M3 , f _M4 , and f _M5 from 0.5 GHz to 3.5 GHz.

  In addition, since the ground plane 102 and the radiating element 106 are arranged close to each other, the ground plane 102 and the radiating element 106 are electromagnetically coupled in each operating frequency band to generate a current in the ground plane 102. As a result, since the ground plane 102 also operates as an antenna, band characteristics and radiation characteristics are improved.

  As described above, the antenna device according to the present embodiment can resonate in a plurality of frequency bands by the ground plane provided with the feeding point and the radiating element.

  Next, an antenna device according to a second embodiment of the present invention will be described with reference to FIG.

  The antenna device according to the present embodiment connects the other end of the radiating element to the ground plane in the vicinity of the feeding point in the antenna device according to the first embodiment. That is, in the antenna device according to the first embodiment, the number of connection points is increased, and there is a difference in the connection method between the radiating element and the ground plane. Hereinafter, the difference will be described.

  The other end portion opposite to the one end connected to the feeding point of the radiating element 106 is connected to the ground plane 102 by the connection point 108. The radiating element 106 has a length that acts as an (n + 1) / 2 wavelength loop antenna (n is an integer of n> 1) in each operating frequency band.

  Next, the operation of the antenna device according to the present embodiment will be described with reference to FIG.

In the lowest frequency band f _L1 in the operating frequency, the total length of the radiating element 106 is about one wavelength, so that a current of one wavelength is generated and acts as a one-wavelength loop feeding radiating element.

In the frequency band f _L2 , the entire length of the radiating element 106 is about 3/2 wavelength, so that a current of 3/2 wavelength is generated and acts as a 3/2 wavelength loop feeding radiating element.

In the frequency band f _L3 , the total length of the radiating element 106 is about two wavelengths, so that a two-wavelength current is generated and acts as a two-wavelength loop feeding radiating element.

  Next, frequency characteristics of the voltage standing wave ratio at the antenna feeding point of the antenna device according to the present embodiment will be described with reference to FIG.

It can be seen that the antenna device according to the present example resonates in five frequency bands f _L1 , f _L2 , f _L3 , f _L4 , and f _L5 from 0.5 GHz to 3.5 GHz, for example.

  In addition, since the ground plane 102 and the radiating element 106 are arranged close to each other, the ground plane 102 and the radiating element 106 are electromagnetically coupled in each operating frequency band to generate a current in the ground plane 102. As a result, since the ground plane 102 also operates as an antenna, the radiation characteristics are improved.

  As described above, the antenna device according to the present embodiment can resonate in a plurality of frequency bands by the ground plane including the feeding point and the connection point and the radiating element.

  Next, an antenna device according to a third embodiment of the present invention will be described with reference to FIG.

  The antenna apparatus according to the present embodiment includes at least one switch element that connects the other end of the radiating element and the ground plane in the vicinity of the feeding point in the antenna apparatus according to the first embodiment. That is, the antenna device according to the first embodiment has a configuration in which the number of switch elements is increased, and there is a difference in the connection method between the radiating element and the ground plane. Hereinafter, the difference will be described.

  A switch element 110 is connected to the other end opposite to one end connected to the feeding point of the radiating element 106, and is connected to the ground plane 102 via the switch element 110.

  The switch element 110 is composed of, for example, a GaAs diode, and is controlled to be non-conductive (off) and conductive (on).

  The operation of the antenna device according to this example will be described.

  First, when the switch element 110 is controlled to be in a non-conductive state, it operates as a (2n + 1) / 4-wavelength monopole antenna (n is n> 1) as in the antenna device described in the first embodiment. For this reason, it can resonate in a plurality of frequency bands.

  Next, when the switch element 110 is controlled to be in a conductive state, it operates as an (n + 1) / 2 wavelength loop antenna (n is n> 1) as in the antenna device described in the second embodiment. For this reason, it can resonate in a plurality of frequency bands.

  Next, the frequency characteristics of the voltage standing wave ratio at the antenna feeding point of the antenna apparatus according to the present embodiment will be described with reference to FIG.

In the antenna device according to the present embodiment, for example, 10 frequency bands f _M1 , f _L1 , f _M2 , f _L2 , f _M3 , f _L3 , f _M4 , f _L4 , f _M5 , 0.5 GHz to 3.5 GHz, it can be seen that resonates at f _L5.

  In addition, since the ground plane 102 and the radiating element 106 are arranged close to each other, the ground plane 102 and the radiating element 106 are electromagnetically coupled in each operating frequency band to generate a current in the ground plane 102. As a result, since the ground plane 102 also operates as an antenna, the radiation characteristics are improved.

  As described above, the antenna device according to the present embodiment can resonate in a plurality of frequency bands by the ground plane including the feeding point and the switch element and the radiating element.

  Next, an antenna device according to a fourth embodiment of the present invention is described.

  The antenna device according to the present embodiment is the antenna device according to the first to third embodiments, in which the radiating element 106 is arranged along the periphery of the ground plane 102 in parallel with the main surface of the ground plane 102. That is, the plane formed by the radiating element 106 is parallel to the ground plane 102. Thus, by arranging the radiating element 106 in parallel with one main surface of the ground plane 102, the volume required for the antenna device can be reduced. For this reason, a small and thin portable terminal housing can be realized.

  Next, the distance between the radiating element and the ground plane in the antenna device described above will be described with reference to FIG.

  In the antenna device 100 according to the above-described embodiment, for example, the antenna device described with reference to FIG. 10, the distance between the radiating element 106 and the ground plane 102 is d, the value of this d is variable, and all other dimensions are fixed. The shape was also fixed. In this state, when the switch element 110 is in a non-conductive state (OFF) and in a conductive state (ON), a change in the voltage standing wave ratio at each resonance frequency is simulated using a numerical calculation by the moment method. It was. FIG. 12 shows a simulation result when the switch element 110 is turned off (OFF), and FIG. 13 shows a simulation result when the switch element 110 is turned on (ON).

12 and 13, the horizontal axis indicates a value obtained by converting the distance d between the radiating element 106 and the ground plane 102 at the wavelength λa in the lowest frequency band in the operating frequency band, and the vertical axis indicates the voltage at the feeding point 104. Indicates the value of the standing wave ratio.

  12 and 13, it can be seen that the voltage standing wave ratio can be made 5 or less by setting d to about 0.015λa or more in both the non-conduction state (OFF) and the conduction state (ON) of the switch element 110.

  Next, an antenna device according to a fifth embodiment of the present invention is described.

  The antenna device 200 according to the present embodiment forms a diversity antenna by the above-described antenna device. That is, the above-described antenna device is applied to the diversity antenna.

  The antenna device 200 according to the present embodiment is configured using the multi-frequency shared antenna device according to the third embodiment as an antenna constituting the diversity antenna. For this reason, it can resonate in a plurality of frequency bands.

  Further, when the switch element 110 is controlled to be non-conductive, the multi-frequency antenna device described in the first embodiment operates, and when the switch element 110 is controlled to be conductive. It operates as the multi-frequency shared antenna device described in the second embodiment.

  Since the current distribution of the multi-frequency antenna device described in the first and second embodiments is different as described with reference to FIGS. 5 and 8, the radiation characteristics of each n are also different. Accordingly, the correlation coefficient of these multi-frequency shared antenna devices is low, and the switching type diversity antenna device configured using the multi-frequency shared antenna device described in the third embodiment can improve the diversity gain. it can.

  Next, an antenna device according to a sixth embodiment of the present invention is described with reference to FIG.

  The antenna device according to the present embodiment forms a diversity antenna by the antenna device described above. That is, the multi-frequency shared antenna apparatus according to the above-described embodiment is applied to the diversity antenna.

  The antenna device according to this embodiment includes the antenna devices according to the first and second embodiments. In addition, the antenna device according to the present embodiment is configured using the multi-frequency shared antenna device described in the first and second embodiments as an antenna constituting the diversity antenna, and therefore resonates in a plurality of frequency bands. be able to.

  Further, since the current distributions of the antenna devices according to the first and second embodiments are different as described with reference to FIGS. 5 and 8, the radiation characteristics of each n are also different. Therefore, the correlation coefficient of these multi-frequency shared antenna devices is low. For this reason, the diversity antenna apparatus configured using the multi-frequency shared antenna apparatus according to the first and second embodiments can obtain a high diversity gain.

  In the present embodiment, the case where the multi-frequency shared antenna apparatus according to the first and second embodiments is used as the antenna apparatus constituting the diversity has been described. However, the multi-frequency antenna including the switch element according to the third embodiment is used. The same effect can be obtained even if the frequency sharing antenna device is used.

  As described above, the antenna device according to the embodiment of the present invention can be built in a terminal housing having a limited space by arranging the radiating elements by folding them back along the periphery of the ground plane. It can be used in the frequency band.

  The antenna device according to the embodiment of the present invention can change the electrical length of the radiating element by arranging the switch element between the radiating element and the ground plane, and can correspond to an arbitrary resonance frequency. It becomes possible. Furthermore, the diversity gain can be improved by adopting the diversity configuration.

  The antenna device and diversity antenna device according to the present invention can be applied to a terminal of a mobile communication system.

It is the schematic which shows an external protrusion type | mold antenna. It is the schematic which shows a housing | casing type inverted F antenna. It is the schematic which shows a folding-shaped portable terminal. It is the schematic which shows the multi-frequency common antenna apparatus concerning one Example of this invention. It is explanatory drawing which shows the current distribution in each operating frequency band of the multi-frequency common antenna apparatus concerning one Example of this invention. It is explanatory drawing which shows the frequency characteristic of the voltage standing wave ratio in the antenna feeding point of the multifrequency shared antenna apparatus concerning one Example of this invention. It is the schematic which shows the multi-frequency common antenna apparatus concerning one Example of this invention. It is explanatory drawing which shows the current distribution in each operating frequency band of the multi-frequency common antenna apparatus concerning one Example of this invention. It is explanatory drawing which shows the frequency characteristic of the voltage standing wave ratio in the antenna feeding point of the multifrequency shared antenna apparatus concerning one Example of this invention. It is the schematic which shows the multi-frequency common antenna apparatus concerning one Example of this invention. It is explanatory drawing which shows the frequency characteristic of the voltage standing wave ratio in the antenna feeding point of the multifrequency shared antenna apparatus concerning one Example of this invention. It is explanatory drawing which shows the change of the voltage standing wave ratio with respect to the space | interval d of the ground plane and radiation | emission element in the multifrequency shared antenna apparatus concerning one Example of this invention. It is explanatory drawing which shows the change of the voltage standing wave ratio with respect to the space | interval d of the ground plane and radiation | emission element in the multifrequency shared antenna apparatus concerning one Example of this invention. 1 is a schematic diagram illustrating a multi-frequency diversity antenna apparatus according to an embodiment of the present invention.

Explanation of symbols

10, 20, 30, 100, 200 Antenna device 12, 22, 102 Ground plane 14, 24, 104 Feed point 16, 26, 106 Radiation element 108 Connection point 110 Switch element

Claims (7)

Ground plane with feeding point;
A radiating element having one end connected to the feeding point and disposed around the edge of the ground plane;
With
The radiating element has a length acting as a (2n + 1) / 4 (n is an integer of n> 1) wavelength monopole antenna in each operating frequency band. Ground plane with feeding point;
A radiating element having one end connected to the feeding point and disposed around the edge of the ground plane;
With
The radiating element is connected to the ground plane at the other end, and has a length that acts as a (n + 1) / 2 (n is an integer of n> 1) wavelength loop antenna in each operating frequency band. apparatus. The antenna device according to claim 1:
A switch element connected to the other end of the radiating element and electrically connected to the ground plane;
An antenna device comprising: The antenna device according to any one of claims 1 to 3, wherein:
An antenna device, wherein a plane formed by the radiating element is parallel to the ground plane. In the antenna device according to any one of claims 1 to 4,
The distance between the radiating element and the ground plane is about 0.015λa or more when the wavelength in the lowest frequency band of the operating frequency band is λa. Ground plane with feeding point;
A radiating element having one end connected to the feeding point and disposed around the edge of the ground plane;
A switch element connected to the other end of the radiating element and electrically connected to the ground plane;
With
The diversity antenna apparatus according to claim 1, wherein the radiating element has a length that acts as a (2n + 1) / 4 (n is an integer of n> 1) wavelength monopole antenna in each operating frequency band.   A diversity antenna device comprising two of the antenna devices according to any one of claims 1 to 3.

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