JPS6216601A - Rectangular microstrip antenna - Google Patents

Abstract

PURPOSE:To erase a cross polarized wave component by providing symmetrically two pieces of feeding points against the center axis being parallel to a main polarized wave direction of a rectangular radiation conductor element, and executing a feed by an equal phase and an equal amplitude. CONSTITUTION:When a rectangular radiation conductor element 2 constituted of a microstrip is excited by one feeding points 5, since the feeding point 5 is shifted from the center axis being parallel to a (y) axis of the rectangular radiation conductor element 2, a surface current of the (y) axis direction being uniform in the (x) axis direction, and a surface current of the (x) axis direction being uniform in the (y) axis direction flow and become elliptical polarized waves, but when said element is excited so as to become an equal phase and an equal amplitude to one feeding point 5 by a feeding point 11 of a symmetrical position to the feeding point 5 against the center axis being parallel to the (y) axis, each surface current of the (x) direction being uniform in the (y) axis direction is offset each other, and only the surface current of the (y) axis direction being uniform in the (x) axis direction is added. As a result, only a linearly polarized wave of the (y) axis direction is radiated, and a cross polarized wave component is erased completely. In this regard, when the same feeding point is provided in the (x) axis direction, as well, a circularly polarized wave antenna can be constituted.

Description

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

[Conventional technology]

FIG. 4 is a diagram showing an example of a conventional rectangular micro TL tube antenna. In FIG. 4, (1) is a dielectric substrate.

(21 is a rectangular radiation conductor element, (3) is a ground conductor plate, (4
) is a strip feed line, (5) is a rectangular radiating conductor water 1-
(, ",)...S) The operating principle of the conventional rectangular microstrip antenna will be explained next.

5 (al and b) 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. (5) is on the y-axis, Figure 5 (bl) is the case where the feeding point (5) is shifted from the central axis. Considering only the fundamental mode, the feeding point (5) in Figure 5 (a) is ) is on the y-axis, a surface current (6) uniform on the X-axis flows in the y-direction on the rectangular radiation conductor element (2), is called an internal electric field.) E8 has a uniform distribution in the X direction and 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, if the feeding point (5) in Fig. 5 fbl is shifted from the central axis, the surface current (6) that is uniform on the X axis not only flows in the y direction on the rectangular radiation conductor element (2). , the surface current (8) uniform in the y-axis also flows in the rectangular radiating conductor element (2; in the upper kx direction, and the internal electric field E, in the y- and x-directions, respectively,
It has sinusoidal distributions (7) and (9). 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 the example of the conventional rectangular microstrip antenna shown in FIG. 4 is used as a linearly polarized antenna.

As explained above, the polarization characteristics are better when the feed point (5) is placed on the center axis, but due to impedance matching or the overall antenna configuration, the feed point (5) is placed on the center axis. In some cases, it may be necessary to bring the antenna to a shifted position.In that case, cross-polarized components are generated, resulting in a problem in which the performance as an antenna deteriorates.

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 the Problems] The rectangular microscopy unit according to the present invention has the following characteristics:
A second power supply point is provided at a position symmetrical to the first power supply point, and power is supplied with equal amplitude and phase to each other.

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

FIG. 1 is a diagram showing an embodiment of the present invention.

In the figure, (1) to (5) are exactly the same as an example of the conventional rectangular microstrip antenna shown in Figure 4.

I
This is the feeding point of the J-tube feeding line 01. The operating principle of one embodiment of the rectangular microstrip antenna according to the present invention will now be described.

FIG. 2 (at and (bl) are diagrams showing the surface current distribution on the rectangular radiating conductor cord 121 when the feeding point (5n and θD are independent, respectively. Figure 5 (
It is the same as the diagram for explaining the operating principle of an example of the conventional rectangular microstrip antenna of bl, and is
) is equivalent to Figure 2 (-) reversed by 180 degrees along the y-axis. In other words, the surface current (6) is 0 in the y-direction defined by the main polarization direction, and Q remains in the same direction as before. 1 surface current (8) and Q for the X direction which is the cross polarization direction.
l flows in the opposite direction. Therefore, if the feeding amplitude phases to the rectangular radiating conductor element (2) at the feeding point (5) and ■ are made equal in amplitude and in phase with each other, as shown in FIG. The surface current distribution is the surface current Q in the y direction.
4, and the internal electric field E has a sinusoidal distribution QcJ with respect to the surface current I.

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

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment of this invention, FIGS. 2(a) and (b) are diagrams for explaining the operating principle of an embodiment of this invention, and FIG. 3 is an embodiment of this invention. Example surface current distribution,
4 is a diagram showing an example of a conventional rectangular microstrip antenna, and FIG. 5 (at and (b) is a diagram for explaining the operating principle of an example of a conventional rectangular microstrip antenna. In the figure, (1) is a dielectric substrate, A21 is a rectangular radiation conductor element, (3) is a ground conductor plate, (5) is a first feeding point,
0υ is 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] In a rectangular microstrip antenna having a dielectric substrate, a ground conductor plate placed on the lower surface of the dielectric substrate, and a rectangular radiating conductor element facing the ground conductor plate via the dielectric substrate, the main polarization A rectangular microstrip characterized in that a second feeding point is provided at a position symmetrical to the first feeding point with respect to the central axis of a rectangular radiation conductor element parallel to the direction, and electricity is fed with equal amplitude and phase to each other. antenna.