JPH11195922A - Antenna system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antenna system where the antenna is made small by making an external shape of a patch electrode and a ground electrode of a micro strip antenna match that of a ceramics substrate. SOLUTION: In a micro strip antenna, a patch electrode 5 and a ground electrode 6, whose external shapes match that of a dielectric body 4, are formed to upper and lower sides of a ceramics dielectric body 4. In the external shape of the dielectric body 4, four corners 4a, 4b, 4c, 4d are smoothly chamfered and a larger curvature is formed on the one corner 4a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna device mounted on a mobile body such as an automobile and receiving a radio wave transmitted from a satellite for navigation.

[0002]

2. Description of the Related Art GPS (Global Posit
A system called right-handed circularly polarized light is used in a system called a plurality of G orbiting the earth.
In order to efficiently receive radio waves from PS satellites, a receiving antenna having a flat gain over a wide angle and a small axial ratio is desired. A microstrip antenna in which a rectangular or circular patch electrode for radio wave radiation or reception is formed on one surface of a dielectric ceramic substrate with high dielectric constant and low loss characteristics, and a ground electrode is formed on the entire other surface, can be miniaturized. Therefore, it is widely used as an antenna for a mobile communication mobile terminal, a receiving antenna for a mobile navigation mounted satellite navigation, and the like. In this case, the electrodes on one surface and the other surface are generally formed by a method of printing a silver paste or a copper paste on a ceramic substrate, respectively.

In a conventional microstrip antenna using a ceramic substrate, as a method for generating circularly polarized waves, a rectangular shape formed on one surface of a ceramic substrate 34 having a substantially square shape as shown in FIG. There are a method of making the patch electrode 35 rectangular, and a method of cutting off the diagonal corners 45a of the square electrode 45 formed on one surface of the ceramic substrate 44 as shown in FIG. With this configuration, the TM010 mode and the TM100 mode, which have the same resonance frequency and are orthogonal to each other, are separated from each other, so that the resonance frequencies are slightly different from each other. Since the phase difference between the modes is 90 degrees, circular polarization occurs. The reason why the roundness is provided at the corner in the shape of the ceramic substrate itself is to ensure that a uniform pressure is applied when the ceramic is pressed.

The conventional circularly polarized microstrip antenna shown in FIGS. 7 and 8 satisfies the antenna performance such as antenna gain and axial ratio without any problem, but the patch electrodes 35 and 45 on one surface. Is generally smaller than the ground electrode on the other side (not shown), so that the dimensions of the ceramic substrates 34 and 44 are larger than the dimensions of the patch electrodes 35 and 45 on the one side, thus reducing the size of the antenna. It is a cause that hinders.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem. The present invention is directed to a microstrip antenna in which the outer shapes of a patch electrode and a ground electrode are made to match the outer shapes of a ceramic substrate. It aims at miniaturization.

[0006]

An antenna device according to the present invention comprises a dielectric substrate, a radio wave radiating or receiving patch electrode having the same outer shape as the dielectric substrate and provided on one surface of the dielectric substrate; And a ground electrode provided on the other surface of the body substrate and having the same outer shape as the dielectric substrate. According to the present invention, since the outer shapes of the ground electrode and the dielectric substrate are made to match the patch electrodes, when an antenna device having a patch electrode of a fixed size is manufactured, the outer shape of the dielectric substrate is the outer shape of the patch electrode. The size of the antenna device can be reduced, and the size of the antenna device can be reduced. Also, as pointed out in the conventional circularly polarized microstrip antenna, since the shape of the patch electrode on one surface and the shape of the ground electrode on the other surface are different, two types of photo films must be prepared for producing an electrode printing plate. It is necessary to solve the problems that must be performed and the high accuracy that the positioning accuracy between the patch electrode on one surface and the ground electrode on the other surface is about ± 20 μm at the time of printing, which degrades the production yield. it can. That is, according to the antenna device of the present invention, it is possible to use a single type of photo film for producing an electrode printing plate, and furthermore, since printing only needs to be performed so as to match the edge of the ceramic substrate, Printing accuracy and positioning of the front and back electrodes are facilitated.

As the dielectric substrate, a plastics substrate or a ceramics substrate can be used. The dielectric loss tangent (tan δ) of the dielectric substrate is small, and more specifically, 10-3
If it is smaller than the order, the dielectric substrate is not limited to the above materials.

[0008] As a printing material for an electrode, a silver paste or a copper paste can be used. The outer shape of the dielectric substrate itself is not particularly limited as long as it can be used for an antenna, but it is substantially square, and four corners are smoothly cut or cut, and at least one corner is cut. The shape in which R is further increased or R is largely cut is desirable from the viewpoint of generating circularly polarized waves.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the antenna device according to the present invention will be described below with reference to the drawings. As shown in FIG. 1, the antenna device 1 can only see the radome 12 and the coaxial cable 11 from the external structure. The main body of the antenna device 1 is installed on, for example, a roof of a vehicle (not shown), while the coaxial cable 11 is connected to a satellite navigation receiver (not shown). The antenna device 1 will be described in more detail. As shown in FIG. 2, a coaxial cable 11 is connected to the antenna circuit means 2 and an upper case 1 forming a radome 12 is formed.
2a and a lower case 12b. Upper case 12a and lower case 12b are both A
It is made of resin such as BS, and is fixed with screws 14. The antenna circuit means 2 includes a microstrip antenna 3 and a low noise amplifier 16.

In the microstrip antenna 3, as shown in FIGS. 3 and 4, a patch electrode 5 and a ground electrode 6 having outer shapes corresponding to the outer shape of the dielectric 4 are formed on the upper and lower surfaces of the ceramic dielectric 4, respectively. It was done. In FIG. 3, 3b is a feeding point. The outer shape of the dielectric 4 is 4
The four corners 4a, 4b, 4c, 4d,
Further, one corner 4a has a shape with a larger radius. The reason why these corners are rounded is that a uniform pressure is applied to the ceramic dielectric when the ceramic dielectric is pressed.
The degeneracy of the resonance mode is released by the corner portion 4a having a large R, and a circularly polarized wave is generated.

The low-noise amplifier 16 comprises a printed circuit board 7 and electronic components 8 such as transistors, ICs, capacitors, inductors, and resistors, and is covered by a shield case 10 for preventing external noise. A feed pin 14 is inserted into a feed point 3 b of the microstrip antenna 3, and is connected to input terminals on the printed circuit board 7 of the low-noise amplifier 16 by soldering portions 15 and 9, respectively. Further, the coaxial cable 11 is connected to an output terminal on the printed circuit board 7 of the low noise amplifier 16. With the above configuration, a weak radio wave from a GPS satellite received by the microstrip antenna 3 is amplified by about 30 dB by the low noise amplifier 16 and supplied to a satellite navigation receiver (not shown) through the coaxial cable 11. .

FIGS. 5 and 6 show other forms of the microstrip antenna. The microstrip antenna 23 has four corners chamfered, and one corner is particularly large-cut. These corners are chamfered so that a uniform pressure is applied to the dielectric itself when the ceramic dielectric is pressed in the same manner as in the antenna 3 of FIG. The corners 23a which are beveled more than the other three corners resolve the degeneracy of the resonance mode and generate circularly polarized waves. 5 and 6, reference numeral 24 denotes a ceramic dielectric, 25
Is a patch electrode having an outer shape matching the outer shape with the dielectric 24, 26 is a ground electrode having an outer shape matching the outer shape with the dielectric 24, and 23b is a feeding point.

[0013]

In the antenna device according to the present invention, the patch electrode and the ground electrode provided on the upper and lower surfaces of the dielectric substrate have the same outer shape as the dielectric substrate.
When an antenna device having a patch electrode of a certain size is manufactured, the outer shape of the dielectric substrate can be reduced to the outer shape of the patch electrode, and an effect that the antenna device can be downsized can be achieved. In the antenna device of the present invention,
Since the patch electrode and the ground electrode have the same shape, it is possible to use a single type of photo film for producing an electrode printing plate for forming them, and furthermore, the printing is adapted to the edge of the ceramic substrate. Therefore, when forming a patch electrode or a ground electrode on a dielectric substrate by printing, there is an effect that printing accuracy and positioning of the front and back electrodes are facilitated.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of an antenna device of the present invention.

FIG. 2 is a cross-sectional view of the antenna device shown in FIG. 1 taken along the line II-II.

FIG. 3 is a plan view showing a microstrip antenna in the antenna device shown in FIG.

FIG. 4 is an exploded perspective view of the microstrip antenna shown in FIG.

FIG. 5 is a plan view showing another embodiment of the microstrip antenna in the antenna device shown in FIG.

6 is an exploded perspective view of the microstrip antenna shown in FIG.

FIG. 7 is a plan view showing an example of a microstrip antenna in a conventional antenna device.

FIG. 8 is a plan view showing another example of a microstrip antenna in a conventional antenna device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Antenna device 3, 23 Microstrip antenna 4, 24 Dielectric 5, 25 Patch electrode 6, 26 Ground electrode

Claims (1)

[Claims] 1. A dielectric substrate, a patch electrode for radio wave radiation or reception having the same outer shape as the dielectric substrate, provided on one surface of the dielectric substrate, and provided on another surface of the dielectric substrate. An antenna device comprising the dielectric substrate and a ground electrode having the same outer shape.