JPH02180408A - Plane antenna - Google Patents

Abstract

PURPOSE:To improve the axis ratio characteristic of an antenna and to expand an operating band width by successively differentiating the physical posture of a butch antenna element at every 90 deg. by means of each linearly polarized wave, and successively differentiating the length of a line from an antenna element to the output point of a sub-array at every 1/4 wavelength. CONSTITUTION:Four linearly polarized wave batch antenna elements 11-14 are synthesized at an output point Q of the array in same phase. When received frequencies are set outside central frequencies f0 of the antenna, and respective pairs synthesize elliptically polarized waves, the direction of the elliptically polarized waves synthesized by second pairs 13 and 14 is different from the elliptically polarized wave synthesized by the first pairs 11 and 12 by 180 deg.. However, the direction of the elliptically polarized wave synthesized by the fourth and first antenna elements 14 and 11 is different from the elliptically polarized wave synthesized by the first pair by 270 deg.. As a result, a circularly polarized wave is generated at the array output point Q by synthesizing the elliptically polarized wave. Consequently the band width which can receive the circularly polarized wave can drastically be expanded.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a directional planar antenna for microwaves, and in particular to a circularly polarized microstrip patch antenna for satellite broadcast reception.

<Prior Art> A planar antenna in which a large number of linearly polarized patch antenna elements of various shapes as shown in FIG. 4 are arranged on a planar dielectric substrate is known as a microstrip patch antenna. The arrows in the figure indicate the direction of the element, that is, the physical posture.

As shown in FIG. 5, two of these linearly polarized patch antenna elements 1 and 2 form a bare 3. bear 3
Inside, the elements 1 and 2 have physical positions different by 90 degrees, and are connected to the bare output point P by lines 4 and 5 whose line lengths are different by a quarter wavelength.

As shown in FIG. 6, 2 g of identical bears 3.3' are connected to a common output point Q by lines 6, 6' of equal length, forming a subarray 7 or 8. Within each subarray, each linearly polarized patch antenna element is located on the vertex of a quadrilateral, with elements l and 1' in the same position, elements 2 and 2'
are in the same position. The subarray 8 is obtained by rotating the attitude of the subarray 7 by 180°.

The two sub-arrays 7 and the two sub-arrays 8 are combined as shown in FIG. 7 Ca) to constitute a 16-element array 9. Four 16-element arrays 10 are combined as shown in FIG. 7(b) to form a 64-element array 10, and four 64-element arrays 10 are combined as shown in FIG. 7(c) to form a 25-element array 10.
A 6-element array is constructed. In this way, the entire planar antenna is combined to form multiple arrays or higher order arrays, and finally to one output end.

<Problems to be Solved by the Invention> Each bear 3 in the above-mentioned antenna has the following problems due to the difference in the physical posture of each linearly polarized patch antenna element 1 and 2 and the difference in the line length from the element to the output point P. It is configured so that circularly polarized waves are combined at output point P, but circularly polarized waves are accurately combined only when the reception frequency is the antenna center frequency fo, and the reception frequency deviates from fO. Gradually, elliptically polarized waves will be synthesized. This tendency can be seen by combining the two bears 3, 3' into subarray 7.8.
Even if configuring , there is no improvement because within each subarray there are two bears or the same posture. Also, when configuring array 9 by combining four subarrays, subarray 7.
7 and 8.8 are only different in attitude by 180', so the above-mentioned tendency cannot be improved. As a result, the axial ratio characteristics are poor.
The drawback was that the operating bandwidth of the antenna could only be expanded.

Means for Solving the Problems> In order to improve the axial ratio characteristics of the conventional planar antenna as described above, the present invention provides a method for configuring a subarray using four linearly polarized patch antenna elements. The physical postures of the wave patch antenna elements are sequentially varied by 90'', and the lengths of the lines from these linearly polarized patch antenna elements to the output point of the subarray are sequentially varied by 1/4 wavelength. .

In a preferred embodiment, a sub-array according to the invention comprises a first bare comprising first and second linearly polarized patch antenna elements and a third and fourth linearly polarized patch antenna element. the second bear, and the first
and the fourth linearly polarized patch antenna element are in an adjacent relationship l, and the second and third linearly polarized patch antenna elements are also in an adjacent relationship. The line length from the second linearly polarized patch antenna element to the first bare output point is longer by a quarter wavelength than the line length from the first linearly polarized patch antenna element to the same output point, Similarly, the line length from the fourth linearly polarized patch antenna element to the second bare output point is one-quarter wavelength longer than the line length from the third linearly polarized patch antenna element to the same output point. The length of the line from the output point of the first bear to the output point of the array and the length of the line from the output point of the second bear to the output point of the array are 1/2.
Only the wavelength is different.

<Operation> In this invention, radio waves from four linearly polarized patch antenna elements are combined in phase at the output point of the array. Reception frequency or antenna center layer wave number f.

If the elliptically polarized waves are synthesized from each bear, the direction of the elliptically polarized waves synthesized by the second bear will be the same as the first one.
It differs by 180' from the elliptically polarized wave synthesized by the bare beam. However, in addition to these bears, the direction of the elliptically polarized waves synthesized by the second and third antenna elements is 90° different from that of the elliptically polarized waves synthesized by the first bear, and The direction of the elliptically polarized waves synthesized by the antenna element differs by 270 degrees from that of the elliptically polarized waves synthesized by the first bear. As a result, at the output point of the array, a circularly polarized wave is produced by combining these elliptically polarized waves having different directions.

Therefore, the bandwidth in which circularly polarized waves can be received is greatly expanded.

<Example> In FIG. 1, linearly polarized patch antenna elements 11, 1
2.13.14 change the physical posture by 90 degrees in order,
They are arranged in a square shape. antenna elements 11 and 12
constitutes a bear, and antenna element 1 is attached to the output point P of the bear.
1 are connected by a line 15, and the antenna element 12 is connected by a line 16 which is longer than the line 15 by a quarter wavelength. Similarly, antenna elements 13 and 14 constitute a bare, and antenna element 13 is connected to antenna element 1 by a line 17 having the same length as line 15 at output point P' of the bare.
4 are connected to each other by a line 18 having the same length as the line 16. Then, the output point P of one bear is connected to the output point Q of the array by the line 19, and the output point P of the other bear is connected to the output point P of the other bear.
'' are respectively connected to the output point Q of the array by a line 20 which is longer than the line 19 by half a wavelength. 21 is an output line connected to the output point Q.

FIG. 2 shows a modification of the embodiment shown in FIG. 1, in which the orientation of each antenna element 11, 12, 13, 14 differs by 45° from the embodiment shown in FIG. 9
0° difference, track 1 compared to tracks 15 and 17
6 and 18 are longer by a quarter wavelength, and the line 20 is longer by a half wavelength than the line 19.

FIG. 3 shows a 16-element array made up of four 4-element arrays shown in FIG. 2, 4-element arrays 22a and 2.
2b, 22c, and 22d have physical postures of 90 in order.
Each degree is different. Output points Qa and Qb of the four-element arrays 22a and 22b are connected to the coupling point R by lines 23 and 24, respectively, and the four-element arrays 22c and 22
The output points Qc and Qd of d are connected to the lines 25 and 26, respectively.
is connected to the connection point R' by. Connection points R and R
' are connected to the output point S of the 16-element array by lines 27 and 28, respectively. Here, the lines 23 and 25 are of equal length, and the lines 24 and 26 are the lines 23.2 and 25.
5 by a quarter wavelength. Further, the line 28 is longer than the line 27 by one-half wavelength.

FIG. 8 shows the axial ratio-frequency characteristic (solid line) of the antenna according to the present invention using a large number of 16-element arrays shown in FIG.
This is a diagram showing the axial ratio-frequency characteristics (dotted line) of a conventional antenna using the 4-element array shown in Fig. 6 in the manner shown in Fig. 7, and when compared at the level of an axial ratio of 1 dB. In the conventional example, a bandwidth of just less than ±1% can be obtained, whereas in the above embodiment, a bandwidth of just over ±3% can be obtained.

FIG. 9 is a diagram showing the cross-polarization protection ratio-frequency characteristic (solid line) of the antenna according to the present invention described above and the cross-polarization protection ratio-frequency characteristic (dotted line) of the conventional example described above. Comparing at a level with a wave protection ratio of 25 dB, in the conventional example,
While only 1.05% of the bandwidth can be obtained, in the above embodiment, a bandwidth of 4.25% can be obtained.

<Effects of the Invention> As described above, according to the present invention, the axial ratio characteristics of the antenna are improved by changing the attitude and connection of the linearly polarized patch antenna elements in each subarray of the microstrip patch antenna, The operating bandwidth can be greatly expanded.

[Brief explanation of the drawing]

Figure 1 is a configuration diagram of a sub-array implementing this invention, Figure 2
The figure is a configuration diagram of another embodiment of the subarray according to the present invention.
FIG. 3 is a configuration diagram of a 16-element array using the subarray shown in FIG. 2, FIG. 4 is a plan view of various conventional linearly polarized patch antenna elements, and FIG. 5 is a configuration diagram of an antenna element bare.
Figure 6 is a configuration diagram of a conventional sub-array, and Figure 7 is a diagram of a conventional sub-array.
Configuration diagrams of a 6-element array, a 64-element array, and a 256-element array; FIG. 8 is an axial ratio-frequency characteristic diagram of antennas of the present invention and a conventional example; FIG. 9 is a cross-polarization diagram of antennas of the present invention and a conventional example. It is a protection ratio-frequency characteristic diagram. 11... first linearly polarized patch antenna element, 12...
...Second linearly polarized patch antenna element, 13...Third linearly polarized patch antenna element, 14...Fourth linearly polarized patch antenna element, 15-21...Line, P
...output point of the first bear, output point of P', fist, second bear, Q...output point of the sub-array. Patent applicant DAYX Antenna Co., Ltd. Agent Satoshi Shimizu and 2 other talented people! Zuzai 2 Zuzaizu ya Zuzaizu (b) (C) Sai 5 Zugazu frequency ripples (f/f,) Yokai Atsushi Cf/f,)

Claims (1)

[Claims] (1) A large number of linearly polarized patch antenna elements arranged on a planar dielectric substrate and connected to a common antenna output point are grouped together into four subarrays (first to fourth), and each Within the subarray, first and second, second and third, third and fourth, and fourth and first linearly polarized patch antenna elements are arranged adjacent to each other on each vertex of the quadrilateral. and these linearly polarized patch antenna elements are connected to the output point of the sub-array, and the first to fourth linearly polarized patch antenna elements have their physical postures sequentially different by 90 degrees and are connected to the line in order. A circularly polarized planar antenna, characterized in that it is connected to the output point of the sub-array by lines whose lengths differ by a quarter wavelength.