JPH0310242B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a rectangular microstrip antenna constructed using a dielectric substrate.

[Conventional technology]

FIG. 4 is a diagram showing an example of a conventional rectangular microstrip antenna, in which 1 is a dielectric substrate, 2 is a rectangular radiation conductor element, 3 is a ground conductor plate, and 4 is a diagram showing an example of a conventional rectangular microstrip antenna.
is a strip feed line, 5 is a rectangular radiation conductor element 2
This is the feeding point of the strip feed line 4 to. Fourth
The operating principle of the conventional rectangular microstrip antenna shown in the figure will now be explained.

5A and 5B are diagrams of a rectangular radiation conductor element 2 for explaining the operating principle of an example of the conventional rectangular microstrip antenna of FIG. 4. FIG. Figure 5a
Fig. 5b shows a case where the feeding point 5 is on the y-axis, and Fig. 5b shows a case where the feeding point 5 is deviated from the central axis. Considering only the fundamental mode, if the feed point 5 in FIG. 1
The electric field within (hereinafter referred to as the internal electric field) E _Z is uniform in the x direction and has a sinusoidal distribution 7 in the y direction. Therefore, the radiated electric field becomes a linearly polarized wave having a component only in the y direction.

On the other hand, when the feed point 5 in FIG. A surface current 8 also flows on the rectangular radiating conductor element 2 in the x direction, and the internal electric field E _Z has sinusoidal distributions 7 and 9 in the y and x directions, respectively. Therefore, the radiated electric field becomes an elliptically polarized wave having components not only in the y direction but also in the x direction.

[Problem that the invention seeks to solve]

When using an example of the conventional rectangular microstrip antenna shown in Fig. 4 as a linearly polarized antenna,
As explained above, the polarization characteristics are better if the feeding point 5 is located on the central axis, but due to impedance matching or the overall antenna configuration, the feeding point 5 may be placed off the central axis. There's something I need to bring. In that case, there was a problem in that cross-polarized components were generated and the performance as an antenna deteriorated.

The present invention was made to solve these problems, and an object of the present invention is to obtain a rectangular microstrip antenna without cross-polarized components even when the feeding point is shifted from the central axis.

[Means for solving problems]

In the rectangular microstrip antenna according to the present invention, the second feeding point is provided at a position symmetrical to the first feeding point with respect to the central axis of the rectangular radiation conductor element parallel to the main polarization direction, and the second feeding point is provided at a position symmetrical to the first feeding point, and the second feeding point is equidistant to the first feeding point. Power is supplied with equal amplitude and phase.

[Effect]

In this invention, the current flowing in the cross polarization direction is suppressed by providing the second feeding point.

〔Example〕

FIG. 1 is a diagram showing an embodiment of the present invention,
In the figure, 1 to 5 are exactly the same as the example of the conventional rectangular microstrip antenna shown in FIG.
10 and 11 are a newly provided strip feed line and a feed point of the strip feed line 10 to the rectangular radiation conductor element 2, respectively. The operating principle of one embodiment of the rectangular microstrip antenna according to the present invention will now be described.

Figure 2 a and b show feed points 5 and 1, respectively.
1 is a diagram showing a surface current distribution of a rectangular radiating conductor element 2 when there is only one radiating conductor element 1. Figure 2a is the same as Figure 5b for explaining the operating principle of an example of a conventional rectangular microstrip antenna, and Figure 2b is a 180 degree inversion of Figure 2a along the y-axis. It is equal to what was made. That is, in the y direction, which is the main polarization direction, the surface currents 6 and 12 flow in the same direction, and in the x direction, which is the cross polarization direction, the surface currents 8 and 13 flow in opposite directions. Therefore, if the feeding amplitude phases to the rectangular radiation conductor element 2 at feeding points 5 and 11 are made equal in amplitude and phase, the third
As shown in the figure, the surface current distribution on the rectangular radiation conductor element 2 is only the surface current 14 in the y direction, and the internal electric field E _Z is a sine wave distribution 15 for the surface current 14.
becomes. Therefore, the radiated electric field becomes a linearly polarized wave having a component only in the y direction, and exhibits good polarization characteristics.

Incidentally, in the above description, the present invention is applied to a single linearly polarized antenna, but it can also be applied to an antenna that can share two orthogonal polarized waves.

〔Effect of the invention〕

As explained above, the present invention provides a second feeding point at a position symmetrical to the first feeding point with respect to the center axis of the rectangular radiation conductor element parallel to the main polarization direction, and has equal amplitude and phase with each other. By supplying power through the antenna, it is possible to obtain good polarization characteristics even when the power supply point is shifted from the central axis.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing an embodiment of the present invention, Fig. 2 a and b are diagrams for explaining the operating principle of an embodiment of the invention, and Fig. 3 is a diagram showing the surface current of an embodiment of the invention. Figure 4 is a diagram showing an example of a conventional rectangular microstrip antenna, and Figures 5a and b explain the operating principle of an example of a conventional rectangular microstrip antenna. This is a diagram for In the figure, 1 is a dielectric substrate, 2 is a rectangular radiation conductor element, 3 is a ground conductor plate, 5 is a first feeding point, 1
Reference numeral 1 denotes a second feeding point provided at a position symmetrical to the first feeding point 5 with respect to the central axis of the rectangular radiation conductor element 2 parallel to the main polarization direction. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A rectangular microstrip antenna having a dielectric substrate, a ground conductor plate placed on the lower surface of the dielectric substrate, and a rectangular radiation conductor element facing the connection conductor plate via the dielectric substrate, A second feeding point is provided at a position symmetrical to the first feeding point with respect to the central axis of the rectangular radiation conductor element parallel to the main polarization direction, and the electricity is fed with equal amplitude and phase to each other. Rectangular microstrip antenna.