JPS59135904A - Electronic scanning antenna - Google Patents

Abstract

PURPOSE:To reduce the side lobe produced by a quantized phase error at beam scanning by adjusting a phase of an input signal of a phase shifter stepwise as specified with a phase adjuster and setting the phase shifter amount of the phase shifter to a prescribed value. CONSTITUTION:The phase of the input signal to a phase shifter 2i relating to the i-th element antenna 1i is adjusted stepwise by using a phase adjuster 9i based on the phase of an output terminal of a transmitter 7, for example as [-alphar<2m>]D, where alpha is an optional constant, (m) is a natural number, (r) is a distance from the center and [X]D is a value formed stepwise by a step width of D closest to the X. In setting the phase shift amount of the phase shifter 2i as expression I by a control signal from a control circuit 5, the phase of the signal applied to the element antenna 1i is expressed as expression II, where [X]B is a digital phase amount quantized by B closest to the X, beta is a constant corresponding to the beam scannig angle, and B and D are minimum unit phase angles. Thus, the side lobe produced by the quantized phase error at beam scanning is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electronic scanning antenna using multiple phase shifters.

Figure 1 shows a conventional electronic scanning antenna.
1a) ~ (1n) LD element antenna, r2a) ~ r2
n) is a phase shifter; C3a) to (3n) are phase shifter drive circuits;
C4a) to (4n) are transmission lines for power supply, and (5) is control (
b) path, (61 transmit/receive switcher, (7) transmitter, (8
) is the receiver. This electronic scanning antenna has a control circuit (
5) to the phase shifter drive circuits (3a) to (3n).
The beam direction is controlled by setting the amount of phase shift in the phase shifters (2a) to (2n). Figure 2 shows the element west device for a planar array antenna. In this figure, X is the horizontal direction, y is the vertical direction, (la) to (1n)
Indicates the number of children.

By the way, in the conventional antenna of this kind.

For beam scanning, use @child computer to calculate B =
Digital phase changes are performed using a phase angle of 2π/2p ('P: number of bits) as the minimum unit, but each antenna element has a phase error (±B/2) as shown in Figure 3. The electronic scanning antenna according to the present invention eliminates the above-mentioned conventional drawbacks. , the electrical length of the feeding transmission line is changed to disperse the quantization phase error that causes large side lobes in a specific direction.Also, in reality, the electrical length of the feeding transmission line is changed continuously. Since it is not possible to change and give the expression fjE, it is essential to give it in a stepwise manner like this expression fjE in order to realize the hardware. Explain.

In Fig. 4, (ia) to (1n) are element antennas, (2a) to (2n) and phase shift 5, (3a) to (3
n) phase shifter drive circuit; (4a) to (4n) are power feeding transmission circuits; (5) is a control circuit; (6) is a transmission/reception switch;
(7) is the sender, (8j is the receiver, (9a) to (9
n) phase adjuster.

In such a st configuration, the first element antenna (1
1) Adjust the phase of the input of the phase shifter (20) in a stepwise manner as shown in equation (1) using the phase adjuster (91), for example, with the phase of the transmitter output end as a reference .

[-0γ2m) ・・・・・・・・・・・・
... (1) However, a is an arbitrary constant p + ""1
*21..., n, m are natural numbers (1, '2, .
). However, the symbol [X)D means the value when the step width is the step width of D, which is closest to X.

When the phase shift amount of the phase shifter (2I) is set as shown in equation (2) using the control signal from the control circuit (5), the reliable phase supplied to the element antenna r11) is calculated as shown in equation (3). becomes [6
12m-β journey〕・・・・－・・・・・・－・
・・・(2) [6γ2m−β,] −(, γ ) 0 ・・・・・・・・・・・・・・・
(3) However, the symbol [:XJ is closest to X.

This means that the digital phase amount quantized by B is taken. β is a constant corresponding to the beam scanning angle.

In this case, the radiation pattern E of the electronic scanning antenna as a whole (is the antenna element spacing d, and the propagation constant is expressed by equation (4), and the main rope direction where equation (4) is maximum is ( 6) It is expressed by the formula.

E(θ)=f,,eJ kd l Sl nθjCaγ
′”-β・]8 stars=1 −jCαγ2m]9 e=Evening 11eJ(kdisinθ−βil jEe
・・・・・・・・・・・・ (4) Direct = 1 Excitation amplitude of the Ii-th element antenna.

E=[αγ2m-βl] 1 [[αγ]ゎ-βI] ... Song ... (5)
It is.

θ-car"r-!!-)-9-1,-0-------,
(61d Furthermore, given in equation (4), fcE=car2-βr)s-[
[aγ21]9−β1] is (if the quantization phase error CB caused by the discontinuity of the phase shifter is O, then D is also 0).

This error will be explained using FIG. 5. In Figure 5, (I+) to (II+9) from the center of γ0 to γ9
Indicates the distance in terms of element width. Considering the case where the beam is scanned in the x direction, the constant βI regarding the beam scanning of elements (1i) to (li+9) is the same, but the distances of γ0 to γ9 are different, so the value of E in equation (5) is have different values, and the two phase errors are dispersed.

Here, how to give the 1-phase distribution will be explained using diagrams. Figure 6 is a diagram showing the phase distribution given by the phase adjuster, where the xy plane is a plane perpendicular to the antenna boresight direction, and the Z axis represents the phase. FIG. 1 shows the phase of each element position, and is a curved surface with the origin at 0. Next(
Consider a cross section with a curved surface shown in Figure 6. FIG. 7 is a diagram showing a cross section, and a shows the phase shifter (2a) before it is made into a stepped shape.
It is the phase distribution of the input signal of ~(2n), which is expressed by the equation in [ ] of Equation 1 (1), and b is a stepwise version of a, which is the phase distribution that expresses Equation (1). . This phase distribution of b is given to the phase adjuster. C phase shifter (2a) ~ (
Equation (2) is a phase distribution that cancels the phase distribution of the input signal of
) is the phase distribution shown by the first term 72m(r) in [], where d is the phase shift amount of beam scanning and β in [] of Equation (2) is
o e shown in IZ is a distribution obtained by adding the phase distribution of C and the phase distribution of d, and represents the expression in [ ] of Equation 2 (2). The distribution of f jd e is digitized and represents equation (2). Therefore, the combination of one curve f and b is the phase distribution given to the element antennas (1a) to rln). As mentioned above, the electric sill of the power supply transmission line can be changed and provided on the stairs, so 71-
This enables the realization of software.

Figure 8 shows one embodiment of the present invention, which is shown in Figure 4 and uses digital phase shifters (9a) to (9n) for phase adjustment as the six phase adjusters (9a) to (9n). and
The principle is the same as that described above. Fig. 9 shows another implementation of this generator, in which semi-fixed phase shifters (9a) to (9n) shown in Fig. 4 are used. 9a)～(9
k) using n).

FIG. 10 is a diagram showing the amount of phase shift applied to each semi-fixed phase shifter in a certain cross section. In Figure 10, (9a) to (9n) are semi-fixed phase shifters, φ0
〜φ3 phase shift amount is shown. As shown in FIG. 10, the amount of phase shift is determined by step phase shifters φ1 to φ3 corresponding to the element position.
is given. Since each semi-fixed phase shifter is given a phase shift amount corresponding to its element position, the phase shift amount is changed and given to each block. Figure 1111 shows the state of blocking. In the figure, (1a) to (1n) are element antennas, and BL, to BL4 are the boundaries of each block. When the cross section is as shown in Fig. 10, the inner element of BLl in Fig. y7EX1 has a phase shift amount of φ0, BL, and B
A phase shift amount of element number φ1 between L2, a phase shift amount of element number φ3 between BL2 and BL3, and a phase shift amount of element number φ3 between BL3 and 13L4 are given.

FIG. 12 shows another embodiment of the present invention, in which fixed phase shifters (9a) to (9n) are used as the phase adjusters (9a) to (9n) shown in FIG. The amount of phase shift applied to each fixed phase shifter is divided into blocks as shown in FIG. 9, and the principle is the same as that described above. Further, this fixed phase shifter may be of any type as long as it can change the electrical length; for example, it may be one in which the length of a coaxial line or waveguide is changed.

According to this idea, the quantization phase error is dispersed, and large side lobes occurring in a specific direction can be reduced.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram showing a conventional electronic scanning antenna, Figure 2 is a diagram showing the element arrangement of a planar array antenna, Figure 3 is a diagram showing the quantization phase error in the conventional antenna, and Figure 4 is a diagram showing the present invention. Figure 5 shows the distance from the center to the element. Figure 6 shows the phase distribution given to the phase adjuster. Figure 7 shows the phase distribution given to the phase adjuster. A cross-sectional view of the phase distribution, Fig. 8 is a schematic diagram showing one embodiment of the present invention, Fig. 9 is a schematic diagram showing another embodiment of the invention, and Fig. 10 shows the amount of phase shift given to the phase shifter. Figure shown, 1st
Figure 1 shows that the amount of phase shift is divided into blocks, Figure 12
The figure is a schematic diagram showing another embodiment of the present invention, (i
a) to (10) are element antennas, (2a'1 to (2n
) phase shifter, (3a) to (3n) phase shifter drive circuit,
(4a) to (4n) are power feeding transmission lines, (5) is a control circuit, (6) is a transmission/reception switch, (7) is a transmitter, (8)
is the receiver, C9a) to (9n) are the phase adjusters, and γ0 to
The distance from the center of γ9, X is the horizontal direction, and y is the vertical direction. Note that the same or corresponding parts in FIG. 1 are indicated by the same reference numerals. Agent Makoto Kuzuno - Plan 1 Figure 2 Change Figure 4 Figure 5) Figure 6 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12

Claims (1)

[Claims] A plurality of element antennas, a plurality of phase shifters provided corresponding to each of the plurality of element antennas, and a tlJr phase shifter drive circuit provided corresponding to each of the plurality of phase shifters. and,
and a control circuit that provides a control signal corresponding to the beam direction to the phase shifter drive circuit, and controls the main beam direction by causing a required amount of phase deviation in the microwave signal sent from the transmitter. In the electronic scanning antenna, the input signal phase of the phase shifter is C-a72m]. The quantization phase during beam scanning can be adjusted by applying a stepwise pattern as shown in FIG. To reduce sidelobes caused by errors, fC and t
Features an electronic scanning antenna. However, B and D are the minimum weighted phase angles, and a is (2) the electronic scanning antenna according to claim clause (1), characterized in that a phase adjustment digital phase shifter is used as the phase adjustment device. . (3) The electronic scanning antenna according to claim (1), characterized in that a semi-fixed phase shifter is used as the phase adjuster. (4) The electronic scanning antenna according to claim (1), characterized in that a fixed phase shifter is used as the phase adjuster.