JP3323020B2 - Diversity antenna - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diversity antenna used for portable radio equipment and the like, and more particularly to a polarization diversity antenna.

[0002]

2. Description of the Related Art Polarization efficiency is one index indicating the reception performance of an antenna. The polarization efficiency will be briefly described. As shown in FIG. 10, the far radiated electromagnetic field of one antenna has only a component perpendicular to the traveling direction. Here, the discussion will be focused on the electric field of the electromagnetic field. FIG. 11 shows a case where an electric field vector is applied to a polar coordinate system. As shown in the figure, the electric field vector is divided into a θ component and a φ component. These are generally called vertical polarization and horizontal polarization. The proportion of these components radiated is called the polarization characteristic of the antenna. This characteristic depends on the radiation mechanism and structure of the antenna.

When transmitting and receiving between two antennas, at the time of reception, only the inner product of the polarization vectors of the respective antennas of the incoming waves can be received. The value of the inner product of the normalized polarization vectors is called polarization efficiency. FIG. 12 shows an example of this, in which the polarization efficiency between monopole antennas placed horizontally and vertically on the same plane is calculated. A horizontally placed monopole antenna emits only horizontally polarized waves in a horizontal plane. In addition, a vertically placed monopole antenna emits only vertically polarized waves in a horizontal plane. Therefore, at this time, the polarization efficiency becomes zero. When the polarization efficiency is 0, the received electric field strength is 0, and transmission and reception using these antennas becomes theoretically impossible. From the above, when designing an antenna, it is common sense to design the antennas so that the polarization directions of the transmitting and receiving antennas match each other.

If the antenna is fixed on the ground, it is relatively easy to match the polarization even with an antenna having only the polarization of either the θ component or the φ component. However, in a portable wireless device in which an antenna is integrated with a main body, it is very difficult to match the polarization of an antenna having only one of these components with a polarization component. For example, a mobile phone or the like is required to be able to communicate even during a call, or even when stored in a bag or pocket. This is because the inclination of the antenna changes variously due to such a change in the use state.

In summary, since portable radios are used in various states, it is necessary to determine the polarization characteristics of the antenna so that only one polarization can be transmitted / received in a certain direction. Is deteriorated, which may hinder reception. Therefore, for an antenna used in a portable wireless device, an antenna that can change the direction of polarization is desired. As an antenna satisfying such requirements, there is a polarization diversity antenna. This antenna is a method of combining two or more antennas having different polarizations and using a reception signal of one of the antennas having a good reception state.

When this polarization diversity antenna is used in a portable radio, the size of the antenna is limited depending on the frequency. As the frequency goes down, the antenna gets bigger. However, considering the portability of the portable wireless device, it is natural that the compact size is more convenient, and the smaller size of the antenna is often better.

As a method of configuring two small diversity antennas having different polarization characteristics, a method using a single-sided short-circuit patch antenna can be considered. As shown in FIG. 13, the one-sided short-circuited patch antenna is formed by forming an antenna element 102 called a patch antenna on a ground conductor plate 101 and further providing a short-circuit surface 103 on the antenna element 102, so that the half-sized short-circuited patch antenna can be completed. It was made. Reference numeral 104 denotes a feeding point of the antenna element 102.

FIG. 14 is a top view of the antenna element portion of the one-sided short-circuit patch antenna of FIG. As shown in the drawing, one side of the antenna element 102 is short-circuited to the ground conductor plate 10, and the length of two sides adjacent to the short-circuited side is λ / 4 (λ: wavelength). ing. Arrows A, B, and C in the figure indicate the direction and amplitude of the magnetic current when the antenna element 102 is in the operating state, and the amplitude is represented by the thickness of the arrow. As can be seen from this figure, on the two sides indicated by arrows A and B adjacent to the short-circuited side, the magnetic currents have the same amplitude in the opposite directions and do not contribute to radiation because they cancel each other out. . Therefore, only the side with arrow C opposite to the shorted side contributes to radiation. This side is called a radiation end, and the two sides marked with the other arrows A and B are called non-radiation ends.

As described above, the radiation end of the one-sided short-circuit patch antenna is a linear magnetic current source. It is considered that a polarization diversity antenna can be configured by combining two of them and making the radiation ends orthogonal to each other. An example in which such a single-sided short-circuited patch antenna is used in a portable wireless device has already been reported in the Institute of Electrical Information and Communication Engineers, 1985, General Conference 2411, "900 Hz Numerical Pager". However, according to this report and other known examples, no polarization diversity antenna using this one-sided short-circuited patch antenna has been proposed.

The present inventors have conducted various simulations on the case where the one-side short-circuit patch antenna is applied to a polarization diversity antenna, and as a result, it has been found that the following problems may occur. In order to realize a small-sized polarization diversity antenna, it is expected that the two antennas have different polarizations. However, depending on the arrangement method of the two antennas, a common component occurs in the polarization components, and the diversity characteristics are degraded.

FIGS. 15 and 16 show an example of the configuration of a one-sided short-circuit patch antenna used in the simulation, and the dimensions and arrangement of each part are as shown in the figures. FIGS. 17 and 18 show calculated values of the radiation patterns of the antennas of FIGS. 15 and 16, respectively. The antenna of FIG.
Since the radiation end (side facing the short-circuit side) is parallel to the z-axis, it is expected that only the φ component is radiated. However, as shown in FIG. 17, the difference between the maximum directivity gains of the two polarization components θ component and φ component is 3d.
B, and the directions of the maximum directivity are almost the same. That is, contrary to expectation, the polarization component of the radiation characteristic of this antenna has both the θ component and the φ component. On the other hand, the antenna of FIG. 16 is arranged so as to be orthogonal to the antenna of FIG. 15, that is, the radiation end is parallel to the x-axis, and the radiation pattern of this antenna has only the θ component as shown in FIG. Not radiated.
That is, when a diversity antenna is configured by combining the two antennas shown in FIGS. 15 and 16,
The θ component becomes common.

In a diversity antenna, it can be said that the smaller the correlation between the received signals of the antennas, the better the diversity characteristics. The fact that the two antennas have a common polarization component (θ component in the above example) as described above means that the correlation between the signals is large, and therefore the diversity characteristics are poor, and the reception characteristics of the radio are degraded. Leads to As described above, when the polarization diversity antenna is configured by using the one-side short-circuited patch antenna, the deterioration of the diversity characteristic becomes a problem.

One of the causes of unexpected polarization components as in the antenna shown in FIG. 15 is considered to be that radiation from the ground conductor plate 101 cannot be ignored. That is, from the antenna to the ground conductor plate 10
1 flows in the longitudinal direction of the ground conductor plate 101, and undesired θ components generated by this current component are radiated. However, there is no report that reveals that such a problem occurs, to the knowledge of the inventors, and, of course, no report has been made to solve such a problem.

[0014]

As described above, conventionally,
The one-sided short-circuited patch antenna is used as a portable radio antenna because of its advantage that it can be formed in a small size. However, there is no example applied to a polarization diversity antenna particularly desired as a portable radio antenna. Further, when this one-side short-circuited patch antenna is simply used as a polarization diversity antenna, there is a problem that the diversity characteristics are deteriorated. SUMMARY OF THE INVENTION An object of the present invention is to provide a diversity antenna that can obtain good diversity characteristics by using a one-side short-circuit patch antenna.

[0015]

In order to solve the above-mentioned problems, a diversity antenna according to the present invention is provided with a rectangular ground conductor plate, and disposed on the same surface facing the ground conductor plate. First each having a shorted side shorted to the plate
And a second antenna element. The first antenna element is disposed substantially at the center in the direction of the first side of the ground conductor plate such that the short-circuit side is parallel to the first side of the ground conductor plate. Is disposed substantially at the center in the direction of the second side of the ground conductor plate such that the short-circuit side is parallel to the second side adjacent to the first side of the ground conductor plate. . The shape of the ground conductor plate is particularly preferably rectangular.

Also, a diversity antenna according to the present invention has a switch for selectively connecting each feed point of the first and second antenna elements to a receiving circuit system, and a switch for connecting the switch to a signal from the receiving circuit system. And a control circuit for controlling based on the control signal.

[0017]

The diversity antenna according to the present invention has the antenna elements of two one-sided short-circuited patch antennas on the same ground conductor plate, and each radiation end, that is, the side opposite to the short-circuit side is adjacent to the ground conductor plate. They are arranged so as to be parallel to the two sides. Therefore, it can be considered that a polarized component from the antenna element and a polarized component from the ground conductor plate, which are orthogonal to each other, are radiated. In this case, the polarization component radiated from the ground conductor plate when power is supplied to one of the two short-circuited patch antennas is the same as the polarization component radiated from the antenna element of the other short-circuited patch antenna. Therefore, it is necessary to consider the deterioration of the diversity characteristics.

Here, assuming that the antenna elements constituting the two single-sided short-circuited patch antennas are located at the center of two adjacent sides of the ground conductor plate as in the present invention, the ground conductor, which is an undesired polarized component, The radiation from the plate is suppressed. As a result, it is possible to prevent the diversity characteristics from deteriorating, which is a problem when a diversity antenna is configured using a one-side short-circuit patch antenna.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings, but before that, the principle of the present invention will be described. In the present invention, by arranging the antenna elements constituting the two single-sided short-circuited patch antennas at the respective center portions in the directions of two adjacent sides of the ground conductor plate, a diversity antenna using the single-sided short-circuited patch antenna can be provided. The problematic radiation from the ground conductor plate is suppressed.

FIG. 1 shows the relationship between the position (distance 1 in the figure) of the antenna element constituting the one-sided short-circuit patch antenna on the ground conductor plate and the ratio Pθ / Pφ of the radiated power of the two polarized components of φ and θ. Is shown in the form of a graph, and this is what the inventors have clarified for the first time. In this example, the radiation end of the antenna element (the side opposite to the short-circuited side) is parallel to the z-axis, so that the polarization component radiated from the antenna element is expected to be the φ component. As is clear from the graph, when the position of the antenna element is at the end of the ground conductor plate, the θ component which is an undesired polarization component is also radiated. However, by moving the antenna element from the end of the ground conductor plate to the center, the undesired polarization component, the θ component, decreases, and according to the present invention, the central portion (in the example shown in FIG. ), It can be seen that this θ component is minimized. The reason why the unwanted polarization component from the ground conductor plate is minimized by disposing the antenna element at the center of the ground conductor plate as described above can be explained as follows.

FIG. 2A shows a current distribution on the AA 'line on the surface of a one-side short-circuited patch antenna in which an antenna element 2 having a short-circuited side 3 is disposed at a corner of a ground conductor plate 1 as shown in FIG. Where (b) is the current amplitude and (c) is the phase. As shown in the figure, a strong current distribution is generated near the antenna element 2, and the phase of the current on the antenna element 2 changes so that the phase gradually becomes opposite from one end to the other end of the antenna element 2. are doing. When the phase difference is 180 °, the radiation from there is canceled out, and the radiation level is reduced. From the graph of this current distribution, it is clear that radiation from the current distributed on the antenna element 2 cancels out to some extent, but does not completely cancel out. Further, the radiation from the current distributed on the ground conductor plate 1 remains as it is.

On the other hand, FIG. 3 shows the calculated value of the current distribution on the AA 'line on the surface of the one-side short-circuited patch antenna in which the antenna element 2 is arranged at the longitudinal center of the ground conductor plate 1 as shown in FIG. (B) is the current amplitude, as in FIG.
(C) is the phase. Looking at the current distribution, the amplitude of the current is distributed symmetrically with respect to the center of the antenna element 2. On the other hand, if attention is paid to the phase distribution of the current, the phase distribution is 180 ° although it is symmetrical like the amplitude distribution. In this case, most currents cancel each other, and the radiated power is significantly attenuated.

That is, it is considered that the decrease in the unnecessary radiation shown in FIG. 1 is due to the cancellation of the current distribution on the antenna element and the ground conductor plate. In addition, it is considered that the same effect is obtained by arranging the antenna elements such that the ground conductor plate has a symmetrical shape when viewed centering on the antenna element, regardless of the shape of the ground conductor plate.

As described above, by arranging the antenna elements constituting the two single-sided short-circuited patch antennas at the respective center portions in the directions of the two adjacent sides of the ground conductor plate as in the present invention, It can be seen that the emission of the desired polarization component is suppressed, and the deterioration of the diversity characteristics can be prevented. Hereinafter, a specific configuration method of the diversity antenna according to the present invention will be described.

Embodiment 1 FIG. 4 is a perspective view showing a configuration of a diversity antenna according to one embodiment of the present invention.
(A) is a view as viewed from the front side, and (b) is a view as viewed from the back side.

In FIG. 4A, the ground conductor plate 10 is rectangular, and thus has a long side and a short side. Assuming that the used wavelength (wavelength at the operating frequency) is λ, the length of the long side is λ / 2 to 2
It is sufficient that the short side is about λ / 4 and the length of the short side is about λ / 3 to λ / 4. A first portion is provided substantially at the center of the ground conductor plate 10 in the longitudinal direction.
And the second antenna element 12 is disposed substantially at the center in the short side direction. Each of the antenna elements 11 and 12 is formed of a rectangular conductor plate.

First and second antenna elements 11 and 12
The first and second one-sided short-circuit patch antennas together with the ground conductor plate 10 constitute one side parallel to the long side direction of the ground conductor plate 10 of the antenna element 11 and the ground conductor plate 10 of the antenna element 12. One side parallel to the long side direction is a short-circuited side short-circuited to the ground conductor plate 10 by the short-circuit elements 13 and 14, respectively. In this example, each of the short-circuit elements 13 and 14 is formed of a conductor plate having one side formed continuously with the long side and the short side of the ground conductor plate 10 and bent at about 90 ° therefrom. The other sides of the short-circuit elements 13 and 14 are formed continuously with the antenna elements 11 and 12, respectively. That is, in this example, the ground conductor plate 10, the antenna elements 11, 12 and the short-circuit elements 13, 14 are integrally formed by one conductor plate.

The length of the antenna element 11 in the direction parallel to the short side direction of the ground conductor plate 10 and the length of the antenna element 12 in the direction parallel to the long side direction of the ground conductor plate 10 are both λ.
/ 4. The short-circuit element 13 may be provided on one of the two sides parallel to the long side direction of the ground conductor plate 10, and the short-circuit element 14 is provided on the two sides parallel to the short side direction of the ground conductor plate 10. It may be provided on one side. That is, in the figure, both of the short-circuit elements 13 and 14 are provided on the outer side, that is, on the long side and the short side of the ground conductor plate 10, but may be provided on the opposite side, that is, on the inner side. .

The length of the short-circuit elements 13 and 14 is the same as the length of the radiation ends of the antenna elements 11 and 12, and the width of the short-circuit elements 13 and 14 is higher than the height of the antenna elements 11 and 12 from the ground conductor plate 10. Equivalent to These parameters contribute to determining the input impedance of the antenna. The length of the short-circuit elements 13 and 14 is λ / 4 to λ / 20, and the width is λ /
It should just be 30 or more.

The ground conductor plate 10 and the antenna elements 11 and 12 are connected by feed lines 15 and 16, respectively. Since the input impedance of the antenna changes depending on the positions of the feeding points of the antenna elements 11 and 12, it is desirable that these positions be determined so that the impedance of the feeding lines 15 and 16 matches the impedance of the antenna.

The ground conductor plate 10, the antenna element 11, the short-circuit element 13 and the feed line 15 constitute a first one-sided short-circuit patch antenna.
2, the short-circuiting element 14 and the feed line 16 constitute a second one-sided short-circuited patch antenna. Then, a diversity antenna is configured using these two one-side short-circuited patch antennas. The diversity antenna of this embodiment is
It can be formed by bending and processing a single conductive plate having the shape shown in FIG. 5A as shown in FIG. 5B.

On the other hand, as shown in FIG. 4B, a high-frequency switch 21, a radio circuit 22 including a high-frequency receiving circuit, and a control circuit 23 are arranged on the back side of the ground conductor plate 10.
Further, high-frequency cables 24, 25, 26 each formed of a coaxial line for transmitting a radio signal, and low-frequency signal lines 27,
28 are arranged. The high-frequency cables 24 and 25 connect the feeding points of the antenna elements 11 and 12 to the high-frequency switch 21, respectively, and the high-frequency cable 26 connects the high-frequency switch 21 and the radio circuit 22. The signal line 27 connects the wireless circuit 22 and the control circuit 23, and the signal line 28 connects the control circuit 2
3 and the high frequency switch 28 are connected.

FIG. 6 is a block diagram of the diversity antenna of FIG. 4 rewritten. However, A1 and A2 indicate the first and second one-sided short-circuit patch antennas described with reference to FIG. In this example, it is assumed that antenna switching diversity reception is performed.
The operation will be briefly described with reference to FIG.

First, the high frequency switch 21 is connected to the control circuit 23
Patch antennas A1 and A
2 is selectively connected to the wireless circuit 22.
For example, if the antenna A1 is selected here, the radio circuit 22 demodulates the signal from the antenna element A1 and performs detection. At this time, the radio circuit 22 performs detection for a certain period of time, and sends the time average level to the control circuit 23. Next, the control circuit 23 connects the antenna A2 to the wireless circuit 22 this time, for example, by inverting the control signal sent to the high-frequency switch 21. At this time, the time average level of the detection signal obtained by the wireless circuit 22 is also sent to the control circuit 23. The control circuit 23 compares the time-average levels of these two detection signals, determines the antenna to be received based on the magnitude relationship between the levels, and connects the antenna determined by the high-frequency switch 21 to the radio circuit 21 based on the antenna. To the control signal. By performing the above operation at certain time intervals, antenna switching diversity using the two one-side short-circuit patch antennas A1 and A2 can be performed.

In the diversity antenna of this embodiment described above, the antenna elements 11 and 12 are arranged with respect to the ground conductor plate 10 as shown in FIG. It is possible to suppress the emission of unnecessary polarized waves due to the current generated in the power supply 10. Thereby, the first
Since the polarization components of the radiation pattern of the second one-sided short-circuited patch antenna can be made orthogonal to each other, a diversity antenna having good diversity characteristics can be obtained by forming a diversity antenna using these one-sided short-circuited patch antennas. Can be realized.

(Embodiment 2) FIG. 7 shows a diversity antenna according to another embodiment of the present invention, in which only a short-circuit patch antenna and a high-frequency switch are shown. The difference from the first embodiment is that the antenna element 11
A point that a plurality of short-circuit pins 33 and 34 are used as means for short-circuiting the 12 short-circuit sides with the ground conductor plate 10. The spacing and thickness of these shorting pins 33 and 34 will change the resonance frequency of the antenna. Therefore, the parameters are set according to the desired operating frequency.

The second difference from the first embodiment is that the ground conductor plate 10 is formed on one surface of the dielectric substrate 30 and the antenna elements 11 and 12 are formed on the other surface.
As the dielectric substrate 30, a high frequency substrate such as Teflon (registered trademark) is used. The thickness of the dielectric substrate 30 is 1
It may be about 5 mm. A high-frequency switch 31 is disposed on the same surface as the surface of the dielectric substrate 30 on which the antenna elements 11 and 12 are formed.
5, 36, 37, 38 and a ground surface 39 are formed.

The strip lines 35 and 36 are for high frequencies, and the characteristic impedance thereof changes depending on the line width. For example, in order to set the characteristic impedance to 50 Ω, which is usually used, the relative dielectric constant of the dielectric substrate 30 is set to 2.
If the thickness is about 1 mm, the strip lines 35, 3
The width of 6 may be 1-2 mm. Strip line 3
One end of each of the antennas 5 and 36 is connected to the antenna element 11 or 12, respectively. Since the input impedance of the antenna changes depending on the connection position, it is desirable to devise an arrangement so that the impedance of the antenna and the strip lines 35 and 36 can be matched.

The strip line 37 connects a radio circuit (not shown) to the high frequency switch 31 and is used for transmitting radio signals. The strip lines 35, 36 and 37 are for high frequency, while the other strip line 38 is for low frequency.
Is connected to transmit the control signal. The ground plane 39 is used for grounding the high-frequency switch 31 and is connected to the ground conductor plate 10 by short-circuit pins 40.

As described above, in this embodiment, the dielectric substrate 30
, The antenna elements 11 and 12 and the strip lines 35, 36, 37,
38 and the ground plane 39 can be formed at one time by etching, so that mass productivity is improved. Furthermore, in the first embodiment, air is used as the dielectric, but when the antenna is configured using the dielectric substrate 30 as in the present embodiment, there is an advantage that the size of the antenna can be reduced. For example, if the relative permittivity of the dielectric substrate 30 is about 2, the width of the antenna required for λ / 4 in the free space length is set to 2
It can be reduced to about λ / 3 to λ / 6.

(Embodiment 3) FIG. 8 shows another embodiment of the present invention, and shows only the antenna portion. As in the embodiment of FIG. 7, antenna elements 11 and 12 are formed on a dielectric substrate 30 by etching, and these antenna elements 11 and 12 are connected to ground conductor plate 10 by short-circuit pins 33 and 34.
Is short-circuited. In the present embodiment, a conductor plate 41 having the same shape as the antenna elements 11 and 12 is formed on the dielectric substrate 30, and this is connected to the ground conductor plate 10 by short-circuit pins 42.
Is different from the embodiment of FIG. The effect of providing the conductor plate 41 and the short-circuit pin 42 is as follows.

In general, when two antennas are placed close to each other, electromagnetic coupling occurs between the two antennas. Thus, if power is supplied to one antenna, radiation may also be generated from the non-powered antenna even if the other antenna is not supplied with power.

Here, focusing on the first one-sided short-circuit patch antenna including the antenna element 11, if only the antenna element 12 is present on the ground conductor plate 10, the presence of the antenna element 12 causes the dielectric When viewed in the longitudinal direction of the body substrate 30 and the ground conductor plate 10, the geometrical structure of the antenna becomes left-right asymmetric. Moreover, when it is considered that the above-described electromagnetic coupling has occurred, it is expected that radiation will also occur from the second one-sided short-circuit patch antenna including the antenna element 12. Therefore, the ground conductor plate 10
Even if the radiation of the unnecessary polarized waves from the antenna can be canceled, the radiation from the second one-side short-circuited patch antenna remains. Moreover, this second one-sided short-circuited patch antenna
Since it is configured to radiate orthogonal polarization components, the first one-side short-circuited patch antenna acts to generate cross polarization.

The conductor plate 41 newly provided in this embodiment.
The shape and arrangement of the antenna element 11 are determined so as to be symmetric with respect to the antenna element 11 with respect to the antenna element 12. Therefore, when power is supplied to the feeding point of the antenna element 11 (the connection point of the feeding line 15), mutually opposite currents are induced by the electromagnetic field coupling between the antenna element 12 and the conductor plate 41 as shown in FIG. Therefore, it is possible to reduce cross-polarization components generated by these currents.

The present invention is not limited to the above-described embodiment, but can be implemented in various modifications. For example, in the above-described embodiment, the case where the antenna element is rectangular has been described, but the present invention is effective when a patch antenna element having an arbitrary shape is used.

[0046]

As described above, according to the present invention, it is possible to suppress unnecessary radiation of undesired polarization in a single-sided short-circuited antenna, which has been a problem in the prior art, and to achieve excellent diversity characteristics. A diversity antenna suitable for a portable wireless device using a one-side short-circuited patch antenna can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram showing the relationship between the arrangement of antenna elements and cross-polarized component power in a one-sided short-circuit patch antenna.

FIG. 2 is a diagram showing an example of the relationship between the arrangement of antenna elements and the amplitude and phase of current distribution on an antenna in a one-sided short-circuit patch antenna.

FIG. 3 is a diagram illustrating another example of the relationship between the arrangement of the antenna elements and the amplitude and phase of the current distribution on the antenna in the one-sided short-circuit patch antenna.

FIG. 4 is a perspective view showing a schematic configuration of a diversity antenna according to one embodiment of the present invention as viewed from the front side and the back side;

FIG. 5 is a diagram showing an example of a method of manufacturing the diversity antenna of FIG.

FIG. 6 is a block diagram showing a circuit configuration of the diversity antenna of FIG. 4;

FIG. 7 is a perspective view showing a schematic configuration of a diversity antenna according to another embodiment of the present invention.

FIG. 8 is a perspective view showing a schematic configuration of a diversity antenna according to another embodiment of the present invention.

9 is a diagram showing a current flow when power is supplied to a first antenna element in the diversity antenna of FIG. 8;

FIG. 10 is a diagram showing how a plane wave propagates in free space.

FIG. 11 is a diagram showing polarization of an electric field and a coordinate system.

FIG. 12 is a diagram showing a radiation field and a polarization efficiency by dipole antennas orthogonal to each other.

FIG. 13 is a diagram showing a schematic configuration of a one-sided short-circuit patch antenna.

FIG. 14 is a diagram showing a state of a magnetic current distribution of the one-side short-circuit patch antenna of FIG. 13;

FIG. 15 is a diagram showing an example of the arrangement of antenna elements in a one-sided short-circuit patch antenna.

FIG. 16 is a diagram showing another example of the arrangement of the antenna elements in the one-sided short-circuit patch antenna.

FIG. 17 is a diagram showing an example of the radiation characteristic of the one-sided short-circuit patch antenna of FIG. 16;

18 is a diagram showing an example of the radiation characteristics of the one-sided short-circuit patch antenna of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Ground conductor plate 2 ... Antenna element 10 ... Ground conductor plate 11, 12 ... Antenna element 13, 14 ... Short circuit element 15, 16 ... Feeding line 21 ... High frequency switch 22 ... Wireless circuit 23 ... Control circuit 24, 25, 26 ... High-frequency cable 27, 28 Low-frequency signal line 30 Dielectric substrate 31 High-frequency switch 33, 34 Short-circuit pin 35, 36, 37, 38 Strip line 39 Ground plane 40 Short-circuit pin 41 Conductor plate 42 Short-circuit pin

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Hisao Iwasaki 1 Kosaka Toshiba-cho, Saiwai-ku, Kawasaki-shi, Kanagawa Prefecture Toshiba Research & Development Center Co., Ltd. (72) Inventor Yasuo Suzuki Komukai Toshiba-cho, Sai-ku, Kawasaki-shi, Kanagawa No. 1 Toshiba Research and Development Center Co., Ltd. (56) References JP-A-63-318826 (JP, A) JP-A-5-259725 (JP, A) JP-A-2-183634 (JP, A) JP-A Sho 63-318827 (JP, A) JP-A-63-219204 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01Q 21/24 H04B 7/08 H04B 7/10

Claims (2)

(57) [Claims] 1. A rectangular ground conductor plate, and first and second antenna elements arranged on the same surface facing the ground conductor plate and having short-circuited sides short-circuited to the ground conductor plate, respectively. The first antenna element is disposed at a substantially central portion in a direction of the first side of the ground conductor plate so that a short-circuit side thereof is parallel to the first side of the ground conductor plate; The second antenna element is located substantially at the center in the direction of the second side of the ground conductor plate such that the short-circuit side is parallel to the second side adjacent to the first side of the ground conductor plate. A diversity antenna, which is arranged. 2. A switch for selectively connecting a feeding point of each of the first and second antenna elements to a receiving circuit system, and a control for controlling the switch based on a signal from the receiving circuit system. The diversity antenna according to claim 1, further comprising a circuit.