JPH06224623A - Microstrip antenna - Google Patents

Abstract

(57) [Summary] [Object] To provide a microstrip antenna that has a disk-shaped radiation conductor and that transmits and receives circularly polarized waves using a degenerate separation element and that can transmit and receive in multiple frequency bands. [Structure] Stubs 14 are provided on the outer peripheral portion of the disk-shaped radiation conductor 11 at positions of 45 ° and 135 ° clockwise and 45 ° and 135 ° counterclockwise from the degenerate separation element 12a. By adjusting the area of the stub 14, the resonance frequency of the secondary mode is changed, and transmission / reception in a plurality of desired frequency bands is possible. As a result, it is possible to perform transmission / reception in a plurality of frequency bands with one microstrip antenna.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microstrip antenna, and more particularly to a microstrip antenna capable of transmitting / receiving in a plurality of frequency bands of a base frequency and higher modes.

[0002]

2. Description of the Related Art Microstrip antennas (hereinafter referred to as MS
The abbreviation "A" is an antenna for satellite communication, global positioning system (GPS), and even for vehicle guidance beacons provided in vehicles in recent years because of its characteristic that it can be downsized due to its simple structure. Is being used as. Circularly polarized waves are used for the radio waves for satellite communication and GPS, and accordingly, MSA capable of transmitting and receiving circularly polarized waves has been developed. For example, there is known an MSA capable of generating a circularly polarized wave by supplying a signal with a predetermined phase shift from two points at predetermined positions of a disk-shaped radiation conductor.

Further, in Japanese Patent Laid-Open No. 3-80603, a protrusion or a notch called a degenerate separation element is provided at a predetermined position on the outer circumference of a disk-shaped radiation conductor.
An MSA that produces circular polarization is shown. A technique is disclosed in which the resonance frequency is adjusted by changing the size of the protrusion or the notch, and the resonance frequency is adapted to the frequency band used for transmission and reception. As a result, the MSA has a simple configuration without using a phase shifter or the like, and the base frequency is easily adjusted.

[0004]

However, with the recent sophistication of information surrounding roads and traffic, MSA has come to be used for a plurality of applications such as GPS and vehicle guidance beacons as described above, and a plurality of frequencies have been used. There is a long-felt need for an MSA that allows the use of obi. M shown in the above publications
Each of the SAs is considered only for use in the base frequency, and is premised on use in a single frequency band. Therefore, when there are a plurality of uses as described above, it is necessary to provide each MSA as shown in the above publication for each frequency determined for each use.

However, even in such MSA, 2
It has a higher-order mode higher than the resonance frequency. Then, by utilizing this higher-order mode, it is possible to construct an MSA that transmits and receives a plurality of frequency bands with one radiation conductor. However, since the higher-order mode is generated at a frequency having a predetermined magnification of the base frequency, the higher-order mode can be used only when a plurality of frequencies used have a relationship of a predetermined magnification. For example, if one frequency used in the circular antenna is 1.57 GHz, the frequency of the secondary mode is 2.60 GHz, and only this frequency can be transmitted and received. Therefore, the combination of frequency bands that can be transmitted and received is limited, and in fact, there is a problem that transmission and reception in a plurality of frequency bands cannot be performed using the higher order mode.

The present invention has been made in order to solve the above-mentioned problems, and in an MSA having one radiation conductor, an MSA capable of transmitting and receiving in a plurality of frequency bands by utilizing high-order mode resonance is provided. It is an object of the present invention to provide an MSA which can be configured and whose frequency of a higher order mode can be adjusted separately from a base frequency.

[0007]

In order to achieve the above-mentioned object, the MSA according to the present invention supplies electric power from a point other than the center point of a substantially annular or disk-shaped radiation conductor, In a MSA that radiates a circularly polarized wave by providing a degenerate separation element at a position displaced by 45 ° from the feeding point on the outer periphery of, and at a position of ± 45 ° along the outer circumference of the radiation conductor from the degenerate separation element Alternatively, provide a stub at a position of ± 135 °.

[0008]

The present invention has the above-described structure, and the resonance frequency of the higher-order mode can be changed by adjusting the area of the stub.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings.

1 and 2 are schematic views of the MSA of this embodiment, FIG. 1 is a perspective view thereof, and FIG. 2 is a sectional view thereof. The radiation conductor 11 is arranged on the upper surface of the dielectric 5, and the ground conductor 6 is arranged on the lower surface of the dielectric 5. In addition, the power supply line 7 is connected to the radiation conductor 11 and guided below the dielectric 5, and is further connected to a transmission / reception circuit (not shown). The power supply line 7 is guided to the ground conductor 6 with a gap. FIG. 3 is a diagram showing details of the shape of the radiation conductor 11. Degenerate separation elements 12 (12a, 12b) are provided on the outer circumference of the substantially disk-shaped radiation conductor 11 at positions of 45 ° and 135 ° from the feeding point 13. The MSA using this radiation conductor 11 can radiate circularly polarized waves by the degenerate separation element 12 as in the conventional device. A characteristic of this embodiment is that the stubs 14 (14a, 14b, 14c, 14) are provided on the outer circumference of the radiation conductor 11.
d) is provided. The stubs 14 are arranged on the diameter passing through the feeding point 13 and on the diameter orthogonal to this diameter. With reference to the degenerate separation element 12a, the angle is described as positive (+) in the counterclockwise direction. The stub 14a is located at 45 ° from the degenerate separation element 12a, the stub 14b is located at 135 °, and the degenerate separation element 12a is separated from the degenerate separation element 12a. -45
Stub 14c at ° position, stub 1 at -135 ° position
4d is arranged. Stubs 14c and 14b are feeding points 13
A stub disposed on a diameter including the stub 14
a and 14d are stubs on the diameter orthogonal to them.

The radiation conductor 11 as described above can transmit and receive circularly polarized waves by the degenerate separation element 12 at the base frequency, and the frequency of the secondary mode can be adjusted by the stub 14.

FIG. 4 shows the characteristics of the MSA using the radiation conductor 11 shown in FIG. FIG. 4 is an input reflection characteristic diagram, in which the horizontal axis represents frequency and the vertical axis represents voltage standing wave ratio (VSWR). When the voltage standing wave ratio is 1, all the supplied power is radiated, that is, there is no reflection, and transmission / reception is performed at this frequency. In other words, the point where the voltage standing wave ratio becomes the minimum is the resonance point, and in FIG.
57 GHz is the base resonance frequency, and about 2.5 GHz is the secondary resonance frequency. Thus, it can be seen from the basis resonance frequency that the secondary resonance frequency, which is originally around 2.6 GHz, is lowered by about 100 MHz.

5 to 9 are diagrams showing the directional characteristics of the MSA of this embodiment.

FIG. 5 shows the vertical plane directivity when circularly polarized waves in the 1.5 GHz band are received. In this figure, 0 ° indicates the zenith direction. It has an average gain characteristic toward the upper side, and the gain is maximum in the zenith direction. Further, FIG. 6 shows the horizontal plane directivity at the time of receiving circularly polarized waves in the 1.5 GHz band, and it can be seen that it has a substantially uniform gain in all directions.

FIG. 7 shows the horizontal plane directivity when receiving horizontal polarized waves in the 2.5 GHz band, which are 0 °, 90 °, 180 °,
It has directivity in four directions of 270 °. Further, FIG. 8 shows the horizontal plane directivity when receiving the vertically polarized wave in the 2.5 GHz band, which has directivity in four directions of 45 °, 135 °, 225 °, and 315 °. Further, FIG. 9 shows 45 ° of FIG.
It is a directional characteristic in a vertical plane including a diameter in the −225 ° direction. Further, although not shown, the vertical plane directivity of the horizontally polarized wave also shows substantially the same shape, and has a maximum gain in the obliquely upward direction from about 20 ° to about 50 °.

The MSA of the present embodiment has the above-mentioned directivity, and when mounted on a vehicle, the characteristics of the 1.5 GHz band are suitable for GPS, and the characteristics of the vehicle in the 2.5 GHz band. This characteristic is suitable for receiving radio waves emitted from low elevation angles used for guidance.

That is, when receiving radio waves from artificial satellites like GPS, it is necessary to have an average directivity with respect to the entire sky. Also, in order to receive radio waves such as beacons for vehicle guidance sent from transmitters installed on the shoulder posts, etc., consider that there is no problem even if the antenna gain is kept low and the received power is large in the beacon proximity area. Then, it is desirable to have directivity diagonally upward (low elevation angle of about 3 ° to 50 °) in front of and behind the vehicle. Therefore, if the guidance beacon is horizontally polarized,
If the 0 ° direction is set as the front of the vehicle, the directivity can be realized.

FIG. 10 shows another embodiment of the radiation conductor. The radiation conductor 21 has one degenerate separation element 22, and a feeding point 23 is provided at a position 45 ° from the degenerate separation element 22. Further, two stubs 24 for adjusting the resonance frequency of the secondary mode are provided. These are provided at positions of ± 135 ° from the degenerate separation element 22, and are at the same positions as the stubs 14b and 14d of the above-described embodiment.
The input radiation characteristic of the MSA using this radiation conductor 21 is shown in FIG.
Shown in 1. The secondary resonance frequency is 2.50 GHz, which is lower than the frequency of the secondary mode expected from the basic resonance frequency of 1.57 GHz, as in the above-described embodiment.

FIG. 12 shows still another embodiment of the radiation conductor. The radiation conductor 31 has one degenerate separation element 32,
A feeding point 33 is provided at a position 45 ° from the degenerate separation element 32. Further, one stub 34 for adjusting the resonance frequency of the secondary mode is provided. This is provided at a position of + 45 ° from the degenerate separation element 32, and is at the same position as the stub 14c of the above-described embodiment. The input radiation characteristic of the MSA using this radiation conductor 31 is shown in FIG.
Shown in. The secondary resonance frequency is 2.5 GHz, and the base resonance frequency is 1.57 GHz as in the above two embodiments.
The value is lower than the frequency of the secondary mode expected from.

As described above, the radiation conductor has a shape in which the degenerate separation element and the stub are provided on the outer circumference of the disk. It is possible to change the frequency.

[0021]

As described above, according to the present invention, the resonance frequency of the secondary mode can be changed separately from the base resonance frequency by providing the stub and adjusting the length thereof. As a result, when transmitting and receiving a plurality of frequency bands with one MSA, it is possible to select a frequency band that is not limited to the base frequency and the frequency of the predetermined fixed magnification. In other words, according to the present invention, even when a radio wave having a frequency that is not the base frequency and a predetermined fixed magnification thereof is received, the reception can be performed by one MSA by adjusting the resonance frequency of the secondary mode. You can Further, even if the resonance frequency of the secondary mode is adjusted by the stub, it does not affect the radiation pattern at the base frequency.

[Brief description of drawings]

FIG. 1 is a perspective view showing a schematic configuration of a preferred embodiment according to the present invention.

FIG. 2 is a sectional view showing a schematic configuration of the present embodiment.

FIG. 3 is a diagram showing details of the shape of the radiation conductor of the present embodiment.

FIG. 4 is a diagram showing an input radiation characteristic of the MSA of the present embodiment.

FIG. 5 is a diagram showing directional characteristics of the MSA of the present embodiment,
In particular, it is a diagram showing a vertical plane directional characteristic of 1.5 GHz circular polarization.

FIG. 6 is a diagram showing the directional characteristics of the MSA of the present embodiment,
It is a figure which shows a horizontal plane directional characteristic of 1.5 GHz circular polarization especially.

FIG. 7 is a diagram showing directional characteristics of the MSA of the present embodiment,
It is a figure which shows a horizontal plane directional characteristic especially of 2.5 GHz horizontal polarization.

FIG. 8 is a diagram showing a directional characteristic of the MSA of the present embodiment,
It is a figure which shows a horizontal plane directional characteristic especially of 2.5 GHz vertical polarization.

FIG. 9 is a diagram showing the directional characteristics of the MSA of the present embodiment,
It is a figure which shows the vertical-plane directivity characteristic especially of 2.5 GHz vertical polarization.

FIG. 10 is a diagram showing details of the shape of a radiation conductor of another embodiment.

11 is a diagram showing an input radiation characteristic of an MSA using the radiation conductor shown in FIG.

FIG. 12 is a diagram showing details of the shape of the radiation conductor of still another embodiment.

13 is a diagram showing an input radiation characteristic of an MSA using the radiation conductor shown in FIG.

[Explanation of symbols]

 11 Radiation Conductor 12 Degenerate Separation Element 13 Feed Point 14 Stub

Claims (1)

[Claims] 1. A degenerate separation element is provided at a position other than the center point of a substantially annular or disk-shaped radiation conductor, and at a position on the outer periphery of the radiation conductor that is displaced by 45 ° from the feeding point. In the microstrip antenna that radiates circularly polarized waves, stubs are provided from the degenerate separation element along the outer circumference of the radiation conductor at at least one of four positions of about ± 45 ° and about ± 135 °. A microstrip antenna characterized by being provided.