JP2000323918A - Circular polarization type plane antenna, antenna system, radio equipment, and radio system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a small-sized plane antenna which obtains a low axis ratio over a wide band although it has high directional characteristic by rotating the directions of antenna elements of respective blocks by specific radians and shifting the phase of a feeding circuit according to the directions. SOLUTION: A feeding circuit system which is provided with a feeding part 8 at the center part and feeds electricity in series has symmetrical constitution of four blocks 4 to 7 composed of microstrip antenna elements 3 which are halved in an X and a Y direction about the feeding part 8. Then X-axial feeding parts 9 and 10 and Y-axial feeding circuits 11 and 12 are made symmetrical. Further, the directions of microstrip antenna elements 3 are changed by π/2 radians among the four blocks 4 to 7 so that the sequential principle is realized, ant the phase is shifted corresponding to the directions. Here, one π radian phase shifter 15 shits the phases of the X-directional feeding circuits 9 and 10 and a small number of π/2 radian phase shifters 16 shift the phases of the Y-directional feeding circuits 11 and 12, so that the phase shifts can be actualized on the limited surface of a substrate 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circularly polarized antenna using a microstrip antenna in a microwave band, and a radio apparatus and a radio system using the antenna.

[0002]

2. Description of the Related Art Conventionally, a circularly polarized antenna and a radio system using this antenna have been disclosed in Japanese Patent Laid-Open No. 10-16374.
No. 5, a toll on toll roads using a roadside wireless device installed on the side of the road, an on-vehicle device mounted on a car, and a circularly polarized microwave band are known. Japanese Patent Application Laid-Open No. 60-206207 discloses a configuration in which a band that satisfies a low axis ratio is widened by disposing microstrip antenna elements.
The composition of the issue is known.

FIGS. 13 and 14 show Japanese Patent Application Laid-Open No. 10-163745.
1 shows a conventional circularly-polarized antenna described in Japanese Patent No. FIG.
Is a schematic configuration diagram of a circularly polarized antenna, and in FIG.
0 is a ground conductor, 81 is a dielectric substrate, 82 is a microstrip antenna element, and 83 is a planar antenna in which microstrip antennas 82 are arranged in an array. FIG.
Is a schematic configuration diagram of the microstrip antenna element 82 portion, 84 is a feed line, 85 is a cutout for circularly polarized wave excitation, and 86 is an input / output terminal.

The operation of the above configuration will be described below. A desired directivity characteristic is obtained by feeding power to each microstrip antenna element 82 through a feed line 84 formed of a microstrip line on a feed circuit such as a distribution and synthesis circuit on the same plane on the radiation surface side of the planar antenna 83. Can be configured. The microstrip antenna element 82 has a notch 85 for exciting circularly polarized wave.
This allows transmission and reception of circularly polarized radio waves.

A wireless device having such a circularly polarized planar antenna 83 is arranged on a traffic lane of a tollgate on a toll road, and information related to a construction fee is exchanged by on-board equipment mounted on the car by wireless communication. By doing so, it becomes possible to collect the construction fee automatically and without stopping at the tollgate. In addition, the use of circularly polarized waves can reduce the effects of reflected waves on vehicles and the ground surface.

FIG. 15 shows a conventional circularly polarized antenna disclosed in Japanese Patent Application Laid-Open No. 60-206207. In FIG. 15, reference numeral 91 denotes a microstrip antenna element.
The numbers described in the microstrip antenna element 91 in FIG. 15 are sequentially numbered according to the direction of the microstrip antenna element 91 described later and the phase of the shifted feeding circuit. An antenna is formed by arranging the microstrip antenna elements 91 in an array.

The following operation will be described with the above configuration. The microstrip antenna element 91 in each row has N
Elements are sequentially rotated around the boresight axis in Pπ / N radian steps, and the feed phase of each microstrip antenna element 91 is shifted in Pπ / N radian steps in accordance with the rotation. The elements are sequentially rotated around the boresight axis in Pπ / M radian steps, and the feed phase of each microstrip antenna element 91 is shifted in Pπ / M radian steps in accordance with the rotation. It becomes possible to radiate circularly polarized waves satisfying a low axial ratio over a wide band.

[0008]

[0005] Bidirectional wireless communication is used to transmit predetermined information between a roadside wireless device installed on the road of a tollgate booth on a toll road and a vehicle-mounted wireless device mounted on a car. In a system that automatically performs a toll road toll collection process by exchanging data, a plurality of roadside devices may be installed at adjacent tolls. In this case, it is necessary to prevent the in-vehicle unit from erroneously communicating with the roadside wireless device at the adjacent tollgate, and to reduce the directional characteristics of the antenna of each roadside wireless device by two.
It needs to be controlled dimensionally. For this reason, the antenna of each roadside apparatus is constituted by a two-dimensional array antenna composed of many elements.

Since at least the antenna section of the roadside apparatus is installed on the road of the tollgate, it must be firmly installed so as not to be damaged by natural phenomena such as wind. This installation method must be designed according to the size of the antenna part to be attached and the surface responsibility of the part receiving the wind, but the smaller and lighter, the simpler the installation member can be, the lower the cost Becomes

For this reason, as the antenna, a planar antenna in which a microstrip antenna element or a feed circuit is printed on a dielectric substrate is often used. When a circularly polarized wave is radiated by such a planar antenna, there is a problem that the band of the axial ratio of the circularly polarized wave is extremely narrow.

On the other hand, when the sequential principle described in the conventional example is applied to a planar antenna, a plurality of antenna elements are used to replace each element with a sequential module, or each element is changed while changing its direction. It is necessary to supply power using different power supply circuits for each antenna element.As a result, there is a problem that the antenna becomes large or a very complicated power supply circuit must be formed with a microstrip line in a limited space. Had.

[0012]

In order to solve this problem, the present invention provides a microstrip antenna element of 2N ×
In a planar antenna configured as a 2M (N and M are integers) two-dimensional array, the feeding method is a series feeding in which power is fed from a central portion of the two-dimensional array. Assuming four blocks divided into two, the direction of the antenna element of each block is set to π / 2 or π
Π radians and π / 2 or π / 4 radians in accordance with the direction, one π or π / 2 radian phase shifter and N π / 2 or π / 4 radians. It is shifted only by the phase shifter.

Further, in the planar antenna, the antenna element is constituted by a square circularly polarized wave element, and the area of one cut-out portion with respect to the entire area of the square element is constituted by 1.6% to 2.1%. Using a radome material composed of a resin-based material having a ratio εr of 3.5 <εr <4.2 and a thickness t of 2 <t <4, a distance L between the radome material and the plane antenna radiating surface is set to 0.
07λ <L <0.14λ.

Also, in the configuration of the housing containing the original planar antenna and the radome material, a denpa absorbing material is provided between the radome material and the planar antenna. As a result, even when a planar antenna configured by arranging microstrip antenna elements in a two-dimensional array is used, a small planar antenna having a high directional characteristic and a low axis ratio over a wide band, and an antenna device using the same, A wireless device and a wireless system can be realized.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention provides a circularly polarized microstrip antenna element of 2N.times.2M (N, N) so that the directional characteristics in the horizontal and vertical directions have a spindle shape. (M is an integer) in a two-dimensional array configuration, has a microstrip circuit symmetrical in the horizontal and vertical directions, and controls a desired amplitude and phase to each antenna element and feeds it to a horizontal antenna. The directions of all N × M antenna elements in four blocks having an N × M array configuration divided into four in the direction and the vertical direction are sequentially rotated by π / 2 radians for each adjacent block, and The phase of the power supply to the N × M antenna elements in π is determined according to the orientation of the antenna element in the corresponding block.
A π radian phase shifter and 2N π / 2 are added to the horizontal and vertical microstrip circuits in units of / 2 radians.
By providing a radian phase shifter and shifting it, it can be said that it is possible to expand the band of low axis ratio by placing only a few phase shifters in a limited space with a small and thin planar antenna configuration. Has an action.

According to a second aspect of the present invention, in the configuration of the first aspect, the directions of all the N × M antenna elements in each block are sequentially set to π / 4 radian for each adjacent block. Each of the microstrip circuits in the horizontal and vertical directions is rotated by π / 4 radians according to the direction of the antenna element in the corresponding block, and the power supply phase to the N × M antenna elements in each block is rotated. By providing a π / 2 radian phase shifter and 2N π / 4 radian phase shifters and displacing them, only a very small number of phase shifters are arranged in a limited space with a small and thin planar antenna configuration. This has the effect of being able to expand the band with a low axial ratio.

According to a third aspect of the present invention, in addition to the configurations of the first and second aspects, each antenna element is formed of a circularly polarized antenna element having a rectangular shape, and is small and thin. The antenna configuration has an effect that it can be realized that the band with a low axial ratio can be expanded.

According to a fourth aspect of the present invention, in addition to the configurations of the first and second aspects, each of the antenna elements is constituted by a circularly-polarized circular antenna element having a round shape. The antenna configuration has an effect that it can be realized that the band with a low axial ratio can be expanded. The invention according to claim 5 of the present invention is different from the structure according to claim 1 in that each antenna element is formed of a linearly polarized element, and has a small and thin planar antenna configuration and a low axial ratio. Has the effect that it can be realized that the band of the signal can be expanded.

According to a sixth aspect of the present invention, a circularly polarized square microstrip antenna element having a square shape is arranged in a two-dimensional array configuration, and each of the antenna elements is arranged by a horizontal and vertical microstrip circuit. In a planar antenna that controls and feeds a desired amplitude and phase, and an antenna device having a housing enclosing the planar antenna and a radome portion made of a resin-based material formed on an electromagnetic wave emission surface side of the planar antenna, a rectangular antenna element is provided. By increasing the area of the notch from the shape with good low-axis ratio band characteristics of the flat antenna alone and narrowing the distance between the radome and the flat antenna,
Compared to the low-axis ratio band of the flat antenna alone, the antenna device is small and thin, and has an effect that the low-axis ratio band can be expanded.

According to a seventh aspect of the present invention, in the configuration of the sixth aspect, in the rectangular antenna element, when the entire area is S and one notch area is dS,
The size of the notch is 1.6% <dS / S <2.1%, the relative permittivity εr is 3.5 <εr <4.2, and the thickness t is 2
When the distance from the flat antenna radiation surface to the radome portion made of a resin-based material with <t <4 mm is L, 0.07
<L <0.14λ apart, which has the effect of expanding the band of low axial ratio with a small and thin antenna device.

According to an eighth aspect of the present invention, there is provided a small and thin antenna device according to the sixth and seventh aspects, wherein the radome portion is made of an acrylonitrile-styrene-acrylate copolymer resin. Has the effect of expanding the band with a low axial ratio.

According to a ninth aspect of the present invention, in contrast to the configuration of the sixth aspect, since the radome portion is made of polycarbonate, the band of a low axial ratio can be expanded with a small and thin antenna device. It has the action to say.

According to a tenth aspect of the present invention, in addition to the constitutions of the sixth, eighth and ninth aspects, the antenna element is constituted by a circular circularly polarized antenna element having a round shape. This has the effect that the band of the low axis ratio can be expanded by the antenna device.

According to an eleventh aspect of the present invention, in the planar antenna according to the first or second aspect, the microstrip antenna element shape, the configuration of the radome portion, and the housing are defined in the sixth to ninth aspects. The antenna device described above has an effect that the antenna device can be reduced in size and the band with a low axial ratio can be expanded.

According to a twelfth aspect of the present invention, there is provided a housing containing the circularly polarized antenna planar antenna according to any one of the first to fifth aspects and a resin material formed on the electromagnetic wave radiation surface side of the planar antenna. An antenna device having a radome portion,
Or in the antenna device according to claim 6 to 11,
The configuration filled with the radio wave absorbing material between the electromagnetic wave radiation surface of the planar antenna and the radome portion has an effect that the degree of characteristic fluctuation of the planar antenna due to multiple reflection components between the planar antenna and the radome material can be reduced.

According to a thirteenth aspect of the present invention, as compared with the configuration of the twelfth aspect, the absorptivity of the radio wave absorbing material is increased as approaching the side of the antenna. This has the effect of reducing multiple reflection components from a complicated structure.

According to a fourteenth aspect of the present invention, there is provided a radio apparatus for transmitting and receiving electromagnetic waves in the microwave band using the planar antenna or the antenna apparatus according to the first to thirteenth aspects, wherein the low axis ratio of the circularly polarized wave is provided. By using a small and thin planar antenna having a wide band, the wireless device having a small size and high communication reliability can be realized.

According to a fifteenth aspect of the present invention, a wireless system using the wireless device according to the fourteenth aspect has an effect of realizing a small-sized wireless system having high communication reliability.

According to a sixteenth aspect of the present invention, the wireless device according to the fifteenth aspect is installed on a side of a toll road or the like, and a microwave electromagnetic wave band is installed between the wireless device and a vehicle-mounted wireless device mounted on a car. A wireless system that automatically collects tolls related to traffic by wireless communication. By using a small, thin flat antenna with a wide band with a low axis ratio of circular polarization, a small and highly reliable wireless device can be realized. It has the effect that it can be realized.

Hereinafter, an embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG.

(Embodiment 1) FIG. 1 is a schematic diagram showing the structure of a circularly polarized planar antenna having an eight-element by eight-element configuration according to the first embodiment. (b) shows a power supply surface which is the back surface of (a). In FIG. 1, 1 is a planar antenna, 2 is a dielectric substrate, 3 is a microstrip antenna element, 4, 5, 6, and 7 are blocks A obtained by virtually dividing the planar antenna 1 axially symmetrically at a central portion, B,
C, D, and 8 are power supply units; 9, 10 are X-direction power supply circuits;
Reference numerals 1 and 12 denote Y-direction power supply circuits, a black square 13 in FIG. 1, a phase shifter 13, and a white square 1.
4 is a distributor, 15 is a π radian phase shifter, 16 is a π / 2 radian phase shifter, and 17 is a feeding point to each microstrip antenna element 3. FIG. 2 is a cross-sectional view of the planar antenna 1, in which 18 is a ground layer, 19 is a through hole, and 20 is a conductive portion formed on the side surface of the through hole 19 by, for example, plating.
1 is a land.

The operation of the above configuration will be described below. The planar antenna 1 has a dielectric substrate 2 on which a microstrip antenna element 3 is printed and a through hole 19 is provided at a position of a feeding point 17, and feeding circuits 9 to 12 are printed on one side, and a ground layer 18 is formed on the opposite side. Is provided, a through hole 19 is provided at the position of the feeding point 17, and the ground layer 1 is provided.
8, the dielectric substrate 2 provided with a land 21 which is a non-conductive portion having a shape larger than the diameter of the through hole 19 for preventing a short circuit between the conductive portion 20 and the ground layer 18 is attached. After the lamination, the microstrip antenna element 3 and the feed circuits 11 and 12 in the Y direction are electrically connected to each other by forming a conductive portion 20 in the through hole 19 by, for example, performing a plating process.

The planar antenna 1 has a spindle-shaped directional characteristic having a spindle shape in both the X direction and the Y direction. Therefore, desired electric signals having a predetermined phase and amplitude are supplied to each microstrip antenna element 3 so as to be fed. It is composed of a phase shifter 13 and a distributor 14. Therefore, the X-direction power supply circuits 9 and 10 are configured to be symmetrical with respect to the power supply unit 8. Similarly, the Y-direction power supply circuits 11 and 12 have a symmetrical circuit configuration with respect to the power supply unit 8. Therefore, block A4, block B
5, the block C6 and the block D7 have a structure that is axially symmetric with respect to the power supply unit 8.

The microstrip antenna element 3 is formed of a square patch antenna element, and has a cutout shape for radiating a desired circularly polarized wave. On the basis of the block A4, the directions of the microstrip antenna elements 3 of the blocks B5, C6, and D7 are rotated by π / 2 radians. One π-radian phase shifter 15 is inserted into the X-direction feeding circuits 9 and 10 and eight π / 2 radian phase shifters 16 are inserted into the Y-direction feeding circuits 11 and 12 with respect to the feeding circuit of the block A4. The phase is shifted according to the direction of the strip antenna element 3.

As described above, in order to realize an antenna whose directional characteristics in the X direction and the Y direction are symmetrical, such as a spindle shape, a feeder 8 is provided at the center, and a feeder is used in a feeder circuit system that feeds in series. 8, the four blocks 4, 5, 6, 7 composed of a plurality of microstrip antenna elements 3 divided into two in the X and Y directions have a symmetrical configuration, and the X-direction power supply circuits 9 and 10 and the Y-direction power supply The circuits 11 and 12 are made symmetric. Further, four blocks 4, 5, 6,
7, the direction of the microstrip antenna element 3 is changed by π / 2 radian so that the sequential principle is satisfied, and a phase shift corresponding thereto is given. The phase shift is
One π-radian phase shifter 15 allows X-direction power supply circuits 9 and 10
In addition, a small number of π / 2 radian phase shifters 16 may be provided in the Y-direction power supply circuits 11 and 12, so that it is possible to realize the circuit with a limited surface of the substrate 2.

FIG. 3 shows a frequency f constructed by this method.
_This figure shows the effect of widening the axial ratio obtained by the planar antenna 1 in the microwave band of ₀ . FIG. 3 (a)
FIG. 3B shows a measurement example of the planar antenna 1 in which all the microstrip antenna elements 3 are arranged in a uniform direction. FIG. The result.
FIG. 3 shows that the band of the low axis ratio is improved.

As described above, according to the first embodiment, even in the planar antenna 1 printed on the dielectric substrate 2, it is possible to expand a large area of a low axis ratio and satisfy a wide band axial ratio. As a result, the planar antenna 1 can be used as an antenna device, which has an effect that the antenna device can be reduced in size or thickness.

As an example of the configuration of the planar antenna 1,
Although an 8 × 8 element configuration has been described, any configuration may be used as long as symmetry of four blocks can be obtained. Also, an example has been described in which the feeding circuits 9, 10, 11, and 12 are configured on a surface opposite to the surface of the microstrip antenna element 3, but they may be configured on the same surface.

The microstrip antenna element 3
Has been described as a square circularly polarized antenna element, but an element having another shape may be used. Further, even with the linear polarization element, it is possible to radiate a desired circular polarization from the planar antenna 1.

Further, the direction of the microstrip antenna element 3 changed between the four blocks 4, 5, 6, and 7 is changed to π / 4 radian, and a phase shift corresponding thereto is given. The π-radian phase shifter 15 may be changed to a π / 2 radian phase shifter, and the π / 2 radian phase shifter 16 may be changed to a π / 4 radian phase shifter.

(Embodiment 2) FIGS. 4A and 4B are schematic diagrams showing the structure of a circularly polarized antenna having an 8 element × 8 element configuration in Embodiment 2; FIG. Indicates a power supply surface which is the back surface of FIG. In FIG. 4, 30 is a planar antenna, 31 is a dielectric substrate, 32 is a microstrip antenna element composed of a square circularly polarized element, 33
Is a power supply unit, 34 and 35 are X-direction power supply circuits, 36 and 37 are Y-direction power supply circuits, 38 is a phaser indicated by a black square in FIG. 4, 39 is a distributor, and a white square is 39. Reference numeral 40 denotes a feeding point to each microstrip antenna element 32. The cross-sectional view of the planar antenna 30 has a structure shown in FIG.

FIG. 5 is a schematic sectional view of an antenna device 50 incorporating the planar antenna 30, in which 51 is a housing, 52 is a dome provided with a columnar convex portion 53 inside, and 55 is a radio (not shown). The housing 51 and the radome portion 52 are fixed by screws 54 and the like, and the planar antenna 30
Is fixed to the housing.

The operation of the above configuration will be described below. The high-frequency electric signal input from the power supply unit 32 is supplied to each microstrip antenna element 32 with a predetermined phase and amplitude by each of the phase shifters 38 and each of the distributors 39 of the power supply circuits 34 to 37. Electromagnetic waves are emitted with directional characteristics. Since each microstrip antenna element 32 is formed of a square circularly polarized element, the combined electromagnetic wave of each microstrip antenna element 32 also becomes a circularly polarized wave, but a band satisfying a low axis ratio, for example, an axis. The bandwidth of 3 dB is about several percent.

The material of the radome portion 52 is made of a material having a small loss with respect to the transmission of electromagnetic waves and an excellent environmental resistance. A polymer resin-based material is used because of the permeability of the electromagnetic wave, but a part of the electromagnetic wave radiated from the planar antenna 30 is transmitted and radiated while being affected by the material characteristics of the radome portion 52 according to the relative dielectric constant of the material. In addition, a part of the light is reflected on the inner surface of the radome portion 52 and returns to the planar antenna 30 to show complicated propagation. Thus, the characteristics of the single planar antenna 30 are affected by the radome portion 52. Specifically, the shift of the frequency band indicating the low axis ratio and the band change.

FIGS. 6 and 7 show that the radome 52 has a thickness of 3 m.
m, acrylonitrile having a relative dielectric constant of about 3.5 to 4.2
Using a styrene-acrylate copolymer resin (ASA) plate, a micro-band planar antenna 30 having a frequency f ₀
FIG. 6 shows characteristics of electromagnetic waves radiated from the antenna device 50 when the antenna with respect to the distance between the radome portion 52 and the planar antenna 30 is changed. FIG. FIG. 7 shows the change of the frequency, and FIG.
3 shows a change in the bandwidth with an axial ratio of 3 dB or less with respect to the distance to. As shown in FIG. 6, the center frequency periodically changes, and the bandwidth of the low axis ratio greatly changes according to the distance between the radome portion 52 and the planar antenna 30 as shown in FIG. 7. The distance between the planar antenna 30 and the radome portion 52 for which a band can be secured is approximately 0.1λ to 0.2λ in a region close to the radome portion 52 suitable for downsizing the antenna device 50.

FIG. 8A shows the shape of a square microstrip antenna element 32 for radiating circularly polarized waves. As shown in FIG. On the other hand, dS57, which is the area of the notch, is cut out at two places. The shape of the microstrip antenna element 32, ie, dS57 for S56
Is set to, for example, near 1.1%, the planar antenna 3
It is possible to widen the band of the low axis ratio by itself. By increasing this ratio to 1.6 and 2.1%, the low-axis ratio bandwidth of the planar antenna 30 alone becomes narrow, but by combining with the housing 51 and the radome portion 52, the low-axis ratio of the electromagnetic wave radiated from the antenna device 50 is reduced. The band characteristics of the ratio can be improved.

FIG. 9 is a graph corresponding to S56 in the case of using the planar antenna 30 in the micro band of the frequency f ₀ and an acrylonitrile-styrene-acrylate copolymer resin plate having a thickness of 3 mm and a dielectric constant of about 3.5 to 4.2. The change of the bandwidth of the axial ratio 3 dB or less with respect to the ratio of dS57 is shown. As shown in FIG. 9, the band characteristic of the low-axis ratio of the planar antenna 30 alone is not good, and the microstrip antenna element 3 is not good.
From the area dS57 of a general cutout having two shapes, 1.
The width of the cutout is 5 to 2 times larger, and the distance between the radome 52 and the planar antenna 30 is set to 0.07λ to 0.14λ. Can do things.

As described above, the square patch shape of the microstrip antenna element 32 is set to dS56 / S56 of 1.6.
Thickness of about 3.5 to 4.2
The 4 mm radome 52 is placed at a distance from the planar antenna 30.
By installing the microstrip antenna element 32 and the feed circuits 34 to 37 on the dielectric substrate 2,
Can be extended even in the planar antenna 1 on which the antenna is printed, and even when the feeder circuit is not a target, the planar antenna 30 having a microstrip structure as the antenna device 50 that satisfies the axial ratio in a wide band. And the antenna device 50 can be reduced in size or thickness.

The microstrip antenna element 3
2 may be constituted by a circular circular polarization element. 6, 7 and 9 also show a tendency similar to that of the polycarbonate material having a relative dielectric constant of about 3 as the radome material 52.

(Embodiment 3) FIG.
FIG. 3 is a cross-sectional view of the antenna device 50 in FIG. 10 differs from FIG. 5 in that the planar antenna 30 and the radome 5
2, a radio wave absorbing material 58 having a low attenuation characteristic is inserted.

The operation of the above configuration will be described below. As described in the second embodiment, a part of the electromagnetic wave radiated from the planar antenna 30 is multiply reflected between the radome 52 and the planar antenna 30 and deteriorates the characteristics of the planar antenna 30. Antenna 30
The multiple reflection components are attenuated by the radio wave absorber 58 between them.

As described above, by providing the radio wave absorber 58 between the planar antenna 30 and the radome portion 52, it is possible to reduce the characteristic deterioration due to the multiple reflection components between the planar antenna 30 and the radome portion 52. The antenna device 50 having excellent characteristics can be realized.

The effect of the multiple reflection becomes more complicated at the peripheral portion of the planar antenna 30 due to the shape of the radome side surface and the like. Therefore, the attenuation characteristics of the radio wave absorber 58 may be spatially distributed such that the attenuation characteristics become greater toward the peripheral portion.

The radio wave absorber 58 may be filled with urethane foam mixed with a radio wave absorber and filled in the gap between the planar antenna 30 and the radome 52 and fixed.

(Embodiment 4) FIG. 11 shows an antenna device using a circularly polarized microstrip antenna which constitutes a roadside wireless device at a tollgate, and wirelessly communicates with a vehicle-mounted wireless device mounted on a vehicle. FIG. 4 is a schematic view of a vicinity of a tollgate viewed from above for explaining an operation of a toll road of an automatic toll collection system which is a wireless system for exchanging predetermined information in two directions.

In FIG. 11, reference numeral 60 denotes a roadside apparatus, 6
1 is a roadside wireless device provided in an adjacent lane, 62 is a communication region formed by an antenna in the roadside wireless device 60, 63 is a communication region formed by an antenna in the roadside wireless device 61,
64 is a vehicle that has entered the tollgate, 65 is an on-vehicle device mounted on the vehicle 64, 66 is a tollgate lane through which the vehicle 64 passes, 67 is an opposite lane, and 68 is a median strip.

FIG. 12 is a diagram showing a schematic configuration of the roadside apparatus 60. In FIG. 11, reference numeral 50 denotes an antenna device including the planar antenna 1 or 30 described in the first to third embodiments, 70 denotes a wireless circuit including a transmitting circuit and a receiving circuit, and 71 denotes a baseband processing and encryption processing function. , A network 72 to which a plurality of roadside apparatuses are connected, and 73 a central control unit connected to the network 72.

The operation of the above configuration will be described below. When the vehicle 64 enters the tollgate on the toll road, the on-board device 65 and the roadside device 60 mounted on the vehicle 64
Is a two-way communication using circularly polarized electromagnetic waves for information necessary to automatically collect tolls. For example, on the entrance side, entrance information is transmitted from the roadside apparatus 60 and stored in the vehicle-mounted apparatus 65. At the exit-side tollgate, the roadside apparatus 60 can calculate the toll from the entrance side to the exit side by obtaining the entrance information and the personal information relating to the driver from the vehicle-mounted device 65.

If necessary, information relating to charging is transferred to a central control unit 73 which centrally manages information from a plurality of roadside wireless devices 60 in the tollgate via a network 72, for example, from a driver's bank account. By deducting the toll, the toll payment procedure can be automatically performed without stopping the vehicle 64 at the toll booth.

The roadside apparatuses 60 and 61 are connected to the toll gate lane 6
6, for example, a vehicle-mounted device 65 installed at a position 5 m above the ground and mounted on a vehicle 64 passing through the toll gate lane 66.
The directional characteristic of the antenna in the roadside apparatus 60 is controlled so that only the communication with the antenna can be performed. These communication areas 62 and 63
Is set to, for example, a height of 1 m above the ground and a width of 3 m × a length of 4 m. Therefore, as the planar antenna in the roadside apparatus 60, it is possible to use the planar antenna 1 described in the first embodiment, for example, having a directional characteristic that is axially symmetric in both the horizontal and vertical directions.

The use of circularly polarized waves makes it possible to reduce the reflection components from the road surface and the vehicle 64 in accordance with the cross polarization discrimination degree. However, the planar antenna 1 or 30 according to the first to third embodiments can reduce the reflected components. It is possible to secure a band with a low axis ratio, and as a result, it is possible to construct a system with high communication reliability.

As described above, a small roadside apparatus 60 using the planar antenna and the antenna apparatus according to the first to third embodiments and a highly reliable automatic toll collection system for toll roads using the roadside apparatus 60 are realized. It has the effect that it can be done.

In this embodiment, the automatic toll collection system for toll roads has been described.
A wireless device or a wireless system that communicates with a device existing in a limited area using electromagnetic waves may be used.

[0064]

As described above, according to the present invention, a planar type in which a microstrip antenna element of N elements in the horizontal direction and M elements in the vertical direction and a feed circuit symmetrical in the horizontal and vertical directions are printed on the dielectric substrate. In the two-dimensional microstrip array antenna of the above, the direction of the microstrip antenna element is changed by π / 2 or π / 4 radians in four blocks divided into two in the horizontal direction and the vertical direction, and the phase shifter according to the change amount is changed. The vertical direction, horizontal direction
By providing N antennas, a planar antenna with a low axis ratio and a wide band can be realized, and a small and highly reliable wireless device or wireless system using circularly polarized waves may be provided.
An advantageous effect is obtained in that a / 4 radian phase shifter can be realized as a feeder circuit and an antenna device can be realized.

[Brief description of the drawings]

FIG. 1 is a schematic structural diagram of a circularly polarized microstrip antenna according to an embodiment of the present invention.

FIG. 2 is a schematic sectional view of a planar antenna according to one embodiment of the present invention.

FIG. 3 is a diagram showing an axial ratio characteristic of the deformed surface antenna according to one embodiment of the present invention;

FIG. 4 is a schematic structural diagram of a circularly polarized microstrip antenna according to an embodiment of the present invention.

FIG. 5 is a schematic structural diagram of an antenna device according to an embodiment of the present invention.

FIG. 6 is a diagram showing a change in characteristics of the planar antenna according to the embodiment of the present invention;

FIG. 7 is a diagram showing a change in characteristics of the planar antenna according to the embodiment of the present invention;

FIG. 8 is a schematic structural diagram showing a shape of a microstrip antenna element according to an embodiment of the present invention.

FIG. 9 is a diagram showing an effect of improving axial ratio characteristics with respect to the shape of a microstrip antenna element according to an embodiment of the present invention.

FIG. 10 is a schematic structural diagram of an antenna device according to an embodiment of the present invention.

FIG. 11 is a schematic diagram illustrating the operation of the toll road automatic toll collection system according to an embodiment of the present invention when viewed from above near a tollgate;

FIG. 12 is a schematic configuration diagram of a roadside moneyless device according to an embodiment of the present invention.

FIG. 13 is a schematic configuration diagram of a conventional antenna.

FIG. 14 is a schematic configuration diagram of a conventional antenna.

FIG. 15 is a schematic configuration diagram of a conventional antenna.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Planar antenna 2 Dielectric substrate 3 Microstrip antenna element 4 Block A 5 Block B 6 Block C 7 Block D 8 Feeding part 9 Feeding circuit 10 Feeding circuit 11 Feeding circuit 12 Feeding circuit 13 Phaser 14 Divider 15 π radian phase shifter Reference Signs List 16 π / 2 radian phase shifter 17 Feed point 18 Ground layer 19 Through hole 20 Conductor 21 Land 30 Flat antenna 31 Dielectric substrate 32 Microstrip antenna element 33 Feeder 34 Feeder 35 Feeder 36 Feeder 37 Feeder 38 Phase Instrument 39 Distributor 40 Feeding point 50 Antenna device 51 Housing 52 Radome 53 Convex portion 54 Screw 55 Connector 56 S57 ΔS 58 Radio wave absorbing material 60 Roadside wireless device 61 Roadside wireless device 62 Communication area 63 Communication area 64 Vehicle 65 Onboard equipment 66 Fee Location lane 67 Opposite lane 68 Median strip 70 Radio circuit 71 Signal processing unit 72 Network 73 Central controller 80 Ground conductor 81 Dielectric substrate 82 Microstrip antenna element 83 Planar antenna 84 Feed line 85 Notch for circular polarization excitation 86 On Output terminal 91 Microstrip antenna element

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Shinichiro Ueno 3-10-1 Higashi-Mita, Tama-ku, Kawasaki-shi, Kanagawa F-term in Matsushita Giken Co., Ltd. 5J021 AA05 AA06 AA09 AB06 DB03 FA05 FA32 GA08 HA05 HA10 JA02 JA06 5J045 AA02 AA16 CA04 DA10 EA07 GA01 HA03 JA03 KA01 LA01 MA07 NA01

Claims (17)

[Claims] 1. A circularly polarized microstrip antenna element is arranged in a 2N × 2M (N and M are integers) two-dimensional array configuration so that directional characteristics in a horizontal direction and a vertical direction have a spindle shape. In a planar antenna for controlling and feeding a desired amplitude and phase to an antenna element, all N × M antenna elements in four blocks composed of an N × M array configuration divided into four in the horizontal and vertical directions Are sequentially rotated by π / 2 radians for each adjacent block, and the phase of power supply to the N × M antenna elements in each block is changed by π / π in accordance with the direction of the antenna element in the corresponding block.
A circularly polarized planar antenna which is shifted by providing one π radian phase shifter and 2N π / 2 radian phase shifters in horizontal and vertical microstrip circuits in units of 2 radians. 2. The direction of all N × M antenna elements in each block is sequentially rotated by π / 4 radians for each adjacent block, and power is supplied to N × M antenna elements in each block. One π / 2 radian phase shifter and 2N π / 4 radian phase shifters are provided in the horizontal and vertical microstrip circuits by π / 4 radians in accordance with the direction of the antenna element in the corresponding block. 2. The circularly polarized planar antenna according to claim 1, wherein the antenna is deflected. 3. The circularly polarized planar antenna according to claim 1, wherein each antenna element is formed of a square circularly polarized antenna element. 4. A circularly polarized planar antenna according to claim 1, wherein each antenna element is formed of a circular circularly polarized antenna element. 5. The circularly polarized planar antenna according to claim 1, wherein each antenna element shape is constituted by a linearly polarized element. 6. A square-shaped circularly polarized antenna element having two rectangular shapes.
A planar antenna that is arranged in a two-dimensional array configuration and controls and feeds the desired amplitude and phase to each antenna element by horizontal and vertical microstrip circuits, a housing containing the planar antenna, and an electromagnetic wave radiating surface side of the planar antenna In an antenna device having a radome portion made of a resin-based material formed, the area of a cutout portion of a square antenna element is increased from a shape having a good low-axis ratio band characteristic of a single planar antenna, and the area between the radome portion and the planar antenna is increased. A circularly polarized antenna device with a reduced distance. 7. In a rectangular antenna element, when the entire area is S and one notch area is dS, the size of the notch is 1.6% <dS / S <2.1%, When the relative permittivity εr is 3.5 <εr <4.2 and the thickness t is 2 <t <
When the distance from the plane antenna radiating surface to the radome portion made of a resin material of 4 mm is L, 0.07 <L <
7. The antenna device according to claim 6, separated by 0.14λ. 8. The antenna device according to claim 6, wherein the radome portion is an acrylonitrile-styrene-acrylate copolymer resin. 9. The antenna device according to claim 6, wherein the radome portion is made of polycarbonate. 10. The antenna device according to claim 6, wherein the antenna element is a circular-shaped circularly polarized antenna element. 11. The antenna device according to claim 6, wherein in the planar antenna according to claim 1, the microstrip antenna element shape, the configuration of the radome portion, and the housing are provided. 12. An antenna device comprising: a housing enclosing the circularly polarized antenna planar antenna according to claim 1; and a radome portion formed of a resin material formed on an electromagnetic wave radiation surface side of the planar antenna. Item 12. The antenna device according to any one of Items 6 to 11, wherein a space between the electromagnetic wave emission surface of the planar antenna and the radome portion is filled with a radio wave absorbing material. 13. The antenna device according to claim 12, wherein the absorptance of the radio wave absorber increases as approaching the side of the antenna. 14. A wireless device having the planar antenna or the antenna device according to claim 1 for transmitting and receiving an electromagnetic wave in a microwave band. 15. A wireless system having the wireless device according to claim 14. 16. An automatic toll related to traffic between a wireless device according to claim 15 installed on the side of a toll road and a vehicle-mounted wireless device mounted on a car by microwave electromagnetic wave wireless communication. A wireless system that collects information. 17. A microstrip circuit having a symmetrical shape in a horizontal direction and a vertical direction. The microstrip circuit supplies power from a central portion of a two-dimensional configuration, first distributes the power in two in a horizontal direction, and vertically distributes N portions from the horizontal power supply circuit. 2. The circularly polarized planar antenna according to claim 1, wherein the antenna is distributed in directions.