JPS62165406A - Plane array antenna consisting of 16 element cross slots - Google Patents

Abstract

PURPOSE:To reduce the deviation of radiation characteristics by determing the center coordinates of an antenna on an x-y coordinate plane about the length of the base of a cavity resonator. CONSTITUTION:On the x-y coordinate plane, the coordinates of the centers of respective X-type cross slot antennas 1 are (l/2<1/2>, 0), (-l/2<1/2>, 0), (0, l/2<1/2>), (0, -l/2<1/2>), (l.2<1/2>, l/2<1/2>), (l.2<1/2>, -l/2<1/2>), (-2<1/2>.l, l/2<1/2>), (-2<1/2>.l, -l/2<1/2>), (l/2<1/2>, 2<1/2>.l), (-l/2<1/2>, 2.2<1/2>.l), (l/2<1/2>, -2<1/2>.l), (-l/2<1/2>, -2<1/2>.l), (5l/2.2<1/2>, 5l/2.2<1/2>), (5l/2.2<1/2>, 5l/2.2<1/2>), (-5l/2.2<1/2>, 5l/2.2<1/2>), and (-5l/2.2<1/2>, -5l/2.2<1/2>). The vale in said coordinates is an optional value more than the size of the cavity resonator 3.

Description

[Detailed description of the invention] (Prior art and its problems) A cross-slot antenna is used as a circularly polarized antenna, and a cross-slot antenna with a cavity in which a cavity resonator is added to the back side is used in aircraft, automobiles, etc. Widely used as an embedded antenna.

Such cavity-equipped cross-slot antennas are roughly divided into two types depending on the arrangement direction of the slot antenna with respect to the cavity resonator. Figure 1 (al) shows a configuration in which the slots of the slot antenna are arranged in the diagonal direction of the cavity resonator (hereinafter referred to as an X-type cross slot antenna); This figure shows a configuration in which the antenna is arranged parallel to the side surface of the resonator (hereinafter referred to as a ten-shaped cross slot antenna).
2 is a ten-shaped cross slot antenna, and 3 is a cavity resonator.

Here, the antenna arrangement of a 16-element planar array antenna using these cross slot antennas as element antennas is generally a 4×4 square arrangement as shown in FIG. In the figure, (al is the X-type cross slot antenna 1
(hl is a ten-shaped cross slot antenna 2
This is a configuration using

When performing electron beam scanning using the array antenna shown in Fig. 2, a large beam generated in a direction different from the main beam direction, so-called grating lobes, becomes a problem.
In order to suppress this, it is necessary to set the element spacing to about half a wavelength or less at the frequency used. In this case, if slot antennas with the same slot length are used as element antennas within the range that can be physically arranged, the X-shaped cross slot antenna can be arranged more densely than the ten-shaped cross slot antenna, and can be arranged over a wider range. It has the advantage of being able to perform beam scanning. Therefore, an array antenna using an X-shaped cross slot antenna will be described below.

FIG. 3 shows an example of the radiation characteristics of an array antenna using the X-shaped cross slot antenna 1 in the coordinate system shown in FIG. Figure 3(a) shows the direction of θ-45'', φ=0'', and the third example shows the direction of φ-〇° and φ=0'' when the beam is scanned in the direction of θ-45°1φ=45'. φ=45
Here are examples of the characteristics of each of these.

As is clear from the figure, good characteristics with low sidelobe levels can be obtained in the φ-0'' plane shown in (al);
(In the φ=45” plane shown in bl, a fairly high-level grating lobe is generated in the θ−-75° direction. This is due to the fact that in the planar array configuration shown in FIG.
In the Oa plane, the 7-element linear array antenna has an equivalent element spacing of l/f2, and in the φ=45° plane, the element spacing is l
The latter is due to the fact that the element spacing is wider and the number of elements is smaller than the former, which is a drawback of the square array using the X-shaped cross slot antenna 1. .

(Object of the Invention) The present invention is to improve the above-mentioned drawbacks and realize a 16-element cross-slot thousand-sided array antenna that reduces the bias in radiation characteristics.

(Structure and operation of the invention) Hereinafter, the present invention will be explained in detail with reference to the drawings. Figure 4 is X
16 according to the invention using type cross slot antenna 1
An example of the configuration of an element array antenna is shown. In the figure, the center of each X-shaped cross slot antenna 1 is (1/a, O), (-g/ff, O
), (0,l/a>.

(0, -1/JK), (v'Nx, J/ff),
(dz.

-1! /M), (-ME, l/a), (-J
'i(1,-A/ff), (E/J'i, Ji
g>, (-1!/i, 2/f1>, <1
/Jf, -RE>, (-1/6.-di(5f/2
/f, 5β/2ff), (51/2i, -5β/2
ff), (-51/2a, 511/28) and (
-5A/2&,-! M! It's on /2ri. Here, β is
It is any value greater than or equal to the size of the cavity resonator.

FIG. 5 shows an example of the radiation characteristics of the array antenna shown in FIG. 4 in the θ direction for φ=θ'' and within the 456 plane.
, φ=09 and θ=45', which is an example of scanning in the φ=45' direction. As is clear from comparing Figure 5 (al (bl) and Figure 3 (al (bl), in the array antenna of the present invention, there is less deterioration of the characteristics in the φ = 0° plane than in the square array (, In the φ=45° plane, an improvement of about 3 dB can be obtained in the θ=−906 direction where the grating lobe is generated. The interval is β/
It can be considered as a 5-element linear array antenna of E, and β
This is because grating lobes do not occur at about =0.55 wavelength, while on the other hand, within the φ=45° plane, the element spacing is still the main factor! However, the number of elements is equivalently 7
The grating lobes are sharp and
Since the element spacing is also non-uniform, the radiation level in the θ=-90" direction decreases even at a scan angle of θ-45°. Note that in the array configuration of the present invention, when φ=
Although the sidelobe level in the 00 plane is higher than that in the square arrangement, the sidelobe level can be easily lowered even in the play arrangement of the present invention by slight adjustment of the element spacing and excitation phase.

6 and 7 show an example of power feeding for each slot antenna used in the present invention, 12 is a combiner, 13 is a feed line, 14 is a slot antenna, 15 is a 906 hybrid circuit, and 16 is a dielectric It is the body substrate. A.

B is the feeding point, and A and B are at equal distances from the center 0 of the slot. The power supply points A and B are configured to oscillate wJ in the same phase and with the same amplitude.

(Effects of the Invention) As described above, the present invention improves the disadvantage that the radiation characteristics are biased in a square arrangement in a 16-element planar array antenna using the X-shaped cross slot antenna 1 as an element antenna. It is possible to realize an array antenna that obtains good characteristics when performing wide-angle beam scanning.

[Brief explanation of drawings]

Figure 1 (a) (bl is a perspective view showing an example of the configuration of a cross slot antenna, Figure 2 (a) (bl is a perspective view showing an example of the configuration of a 16-element square array antenna, Figure 3 (
al (bl is a diagram showing the radiation characteristics of the square array antenna, FIG. 4 is a perspective view showing a configuration example of the 16-element array antenna according to the present invention, and FIG. 5 is a diagram showing the radiation characteristics of the array antenna according to the present invention. Figure 6(a)(b)
FIG. 2 is a perspective view showing an example of power feeding of a slot antenna used in the present invention. I...X type cross slot antenna, 2...Ten type cross slot antenna, 3...Cavity resonator, 12...
・Synthesizer, 13... Feed line, 14... Slot antenna, 15... 90'' hybrid circuit, 16...
dielectric substrate.

Claims (1)

[Claims] In a cross-slot planar array antenna in which a plurality of cross-slot antennas are arranged in a plane in which the slots of the slot antennas are arranged in the diagonal direction of the cavity resonator, for any l that is longer than the length of the base of the cavity resonator, In the xy coordinate plane, the coordinates of the center of the cross-slot antenna are (l/√2, 0), (-l/√2, 0), (0,
l/√2), (0, -l/√2), (√2l, l/√2
), (√2l, -l/√2), (-√2l, l/√2)
, (-√2l, -l/√2), (l/√2, √2l),
(-l/√2, 2√2l), (l/√2, -√2l),
(-l/√2, -√2l), (5l/2√2, 5l/2
√2), (5l/2√2, -5l/2√2), (-5l
/2√2, 5l/2√2) and (-5l/2√2, -5
1/2√2) A 16-element cross-slot planar array antenna.