JPH04321304A - Polarized wave changeover device for phased array antenna - Google Patents

Abstract

PURPOSE:To select a polarized wave optionally by controlling a phase change in each phase shifter. CONSTITUTION:A high frequency signal of an equal amplitude and an equal phase is inputted to input terminals 1a, 1b of adjacent vertical array pairs. The high frequency signal is subject to phase change by a phase depending on the position of the array pair and in the beam scanning direction and inputted to vertical feeding circuits 4a, 4b. The phase shift of the phase shifter in the entire array antenna is controlled by a controller 3. The high frequency signal inputted to the vertical feeding circuits 4a, 4b is distributed to a distribution ratio and phase depending on the vertical pattern of the array antenna and fed to antenna elements 5a, 5b. Since the antenna elements 5a, 5b are directed so that the plane of the polarized wave radiating from the antenna elements 5a, 5b is directed in a direction different by 45 deg. with respect to the vertical direction, a deviation in the polarized wave plane by 90 deg. is caused between both the waves. Thus, the polarized wave is momentarily switched into a vertical, a horizontal and a circularly polarized wave by varying a phase difference between the adjacent array antenna elements as 0,pi, and pi/2.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phased array antenna, and more particularly to a polarization switching device for a radar phased array antenna that performs polarization switching.

0002

2. Description of the Related Art Taking as an example a phased array antenna that scans a beam in the horizontal direction as a conventional phased array antenna, as shown in FIG. A phase shifter 2 that changes the determined phase amount, a controller 3 that controls the phase amount of the phase shifter 2, and a vertical controller that distributes the output high frequency signal of the phase shifter 2 into amplitudes and phases determined by the vertical pattern of the array antenna. It is configured by horizontally arranging a plurality of vertical arrays each having a feeder circuit 4 and antenna elements 51 , 52 , . . . 5n that radiate the output of the vertical feeder circuit 4 into space.

FIG. 4 is an example of a cylindrical phased array antenna in which a plurality of vertical arrays of FIG. 3 are arranged in a cylindrical shape. In this configuration, phase shifter modules 20a, 20
The high frequency signals inputted to the vertical feed circuits 21a, 21b, .
21b, . . . High frequency signal is vertical feed circuit 2
1a, 21b..., antenna element 22a
(22a1...22an), 22b (22b1...22bn
), . . . and is radiated into space with a unique polarization determined by the antenna elements 22a, 22b, .

0004

[Problem to be Solved by the Invention] Incidentally, in radar, differences in polarization cause differences in radio wave propagation characteristics, so clutter can be suppressed by appropriately selecting polarization according to weather and other conditions. It is known. However, conventional phased array antennas are unable to radiate high-frequency signals with polarizations other than those determined by the antenna elements. That is, in the phased array antenna described above, the polarization of the radiated high-frequency signal is uniquely determined by the polarization of the antenna elements 22a and 22b, and if the polarization of the antenna elements 22a and 22b is horizontal, the radiated high-frequency signal of the phased array antenna is determined by the polarization of the antenna elements 22a and 22b. If the polarization is horizontal, it is vertical if it is vertical, and it is circular if it is circular. Therefore, there is a problem in that it is difficult to suppress cracks. An object of the present invention is to provide a polarization switching device for a phased array antenna that can arbitrarily switch polarization.

[0005]

[Means for Solving the Problems] A polarization switching device for a phased array antenna according to the present invention comprises an array antenna in which antenna elements whose polarization planes are alternately inclined by 45 degrees with respect to the beam scanning direction are arranged in an array, and an antenna. The device includes a plurality of phase shifters connected to each element and capable of changing the high-frequency phase to an arbitrary value, and a controller that controls each phase shifter. The controller sets the phase difference between adjacent antenna elements to at least 0,
It is configured to be switchable between π and π/2.

[0006]

[Operation] According to the present invention, the polarization of the phased array antenna can be arbitrarily switched by controlling the phase shifter of each array antenna using a controller and changing the phase of adjacent antennas. .

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be explained with reference to the drawings. FIG. 1 is a system diagram of a vertical array pair in one embodiment in which the present invention is implemented in a phased array antenna that scans a fixed vertical pattern beam in the horizontal direction. A phase shifter 2a changes the phase of the high frequency signal input to the input terminal 1a by a phase amount determined by the beam scanning direction, and divides the output high frequency signal of the phase shifter 2a into amplitudes and phase shifts determined by the vertical pattern of the array antenna. A vertical feeding circuit 4a and an antenna element 5a (which radiates the output of the vertical feeding circuit 4a into space)
5a1, 5a2,...5an) to form a vertical array. Similarly, for a high-frequency signal input to the input terminal 1b, a vertical array is configured by a phase shifter 2b, a vertical feeding circuit 4b, and an antenna element 5b (5b1, 5b2, . . . 5bn). These vertical arrays are arranged alternately in the horizontal direction, and a controller 3 for controlling the phase amount in the phase shifter is connected to each phase shifter 2a, 2b, and each antenna element of the adjacent vertical array is connected to each phase shifter 2a, 2b. 5a and 5b are set so that their planes of polarization are oriented in directions different from each other by 45 degrees with respect to the vertical direction. It goes without saying that the number of horizontal arrays is determined by the interval and number determined by the beam scanning range, horizontal beam width, and side lobe level.

According to this configuration, high frequency signals of equal amplitude and equal phase are input to the input ends 1a and 1b of the adjacent vertical array pair. The high frequency signals undergo phase changes by phase shifters 2a, 2b by a phase amount determined by the position of the array pair and the beam scanning direction, and are output to vertical feed circuits 4a, 4b. A controller 3 controls the phase shifter phase amount of the entire array antenna. The high frequency signals input to the vertical feed circuits 4a, 4b are distributed at a distribution ratio and phase determined by the vertical pattern of the array antenna, and then fed to the antenna elements 5a, 5b. Since the antenna element 5a and the antenna element 5b have their radiating polarization planes oriented in directions that differ by 45° from the vertical direction, a 90° deviation in polarization plane occurs between them.

Therefore, the array antenna horizontal direction is x
When the vertical direction is the y-axis, the high frequency signal radiated from the antenna element 5a is expressed as y=Ksin ωt x=Ksin ωt. However, K=A/√2, A is the amplitude of the high frequency signal, and ω is the angular frequency. Similarly, antenna element 5b
The high frequency signal that is radiated is expressed as follows: y=Ksin(ωt+θ) x=−Ksin(ωt+θ). However, θ is the phase difference between the high frequency signals fed to the antenna element 5a and the antenna element 5b. The phase difference θ is given by phase shifters 2a and 2b, and controlled by a controller 3.

[0010] Accordingly, when the phase difference θ is 0, the combined radiation signal from the antenna elements 5a and 5b is expressed as y=2Ksin ωt x=0 at a sufficiently far distance, and the polarization is vertical. Furthermore, when the phase difference θ is π, the combined radiation signal of the antenna elements 5a and 5b is expressed as follows at a sufficiently far distance: y=Ksin ωt+Ksin (ωt+π)=Ksin
ωt−Ksin ωt=0 x=Ksin ωt−Ksin(ωt+π)=Ksin
It is expressed as ωt+Ksin ωt=2Ksin ωt, and the polarization is horizontal.

Furthermore, when the phase difference θ is π/2, the combined radiation signal of the antenna elements 5a and 5b is expressed as follows at a sufficiently far distance: y=Ksin ωt+Ksin(ωt+π/2)=Ks
in ωt-Kcos ωt x=Ksin ωt-Ksin(ωt+π/2)=Ks
in ωt+Kcos ωt y2 +x2 =K2 [sin2ωt-2sin ω
t・cos ωt+cos2ωt+sin2ωt+2c
os ωt・sin ωt+cos2ωt]=K2 [
2(sin2ωt+cos2ωt)]=2K2=A2
It is expressed as , and the polarization is circular. In this case, antenna element 5
If the phase fed to antenna element 5b is π/2 ahead of the phase fed to antenna element a, it becomes a right-handed circularly polarized wave, and the phase fed to antenna element 5b is π/2.
If it is delayed by 2, it becomes left-handed circularly polarized wave. Similarly, for the polarization of the radiated high frequency waves of the vertical array pair, the phase shifters 2a and 2b
By providing a phase difference between a pair of vertical arrays, it is possible to instantly and electrically change from vertical to horizontal, right-handed circular, and left-handed circular because no mechanical operation is required.

FIG. 2 shows an embodiment in which the present invention is implemented in a cylindrical phased array antenna having a fixed vertical pattern radiation characteristic. RF module 10a, 10b
The high frequency signal amplified to a desired amplitude value by the phase shifter modules 11a, 11b, . 12a2,...12an),
12b (12b1, 12b2, . . . 12bn), . Antenna element 12a (12a1, 12a2,...
12an), 12b (12b1, 12b2,...12bn
), ... are arranged on the vertical feeding circuit, and the antenna elements 12
The polarization planes of antenna element a and antenna element 12b differ by 90°, and the polarization planes of all antenna elements are tilted by +45° or −45° with respect to the axis of the array antenna. Adjacent vertical arrays form a vertical array pair, and each time the beam scanning direction changes by an angle corresponding to the vertical array spacing, the pair of vertical arrays also shifts by one vertical array. In addition, in circularly polarized radiation, each time the pair of vertical arrays changes, the polarity of the left and right phase relationship is changed to maintain the right-handed or left-handed rotation direction of the polarized waves.

[0013]

As explained above, the present invention tilts the antenna elements alternately at 45 degrees in the beam scanning direction, and specifies the amount of phase change of the phase shifter controlled by the controller between adjacent antenna elements. By changing the phase difference, the polarization of the radiated high-frequency signal of the phased array antenna can be instantly changed from vertical to horizontal to right-handed circular to left-handed circular. There are effects that can be obtained.

[Brief explanation of drawings]

FIG. 1 is a system diagram of a vertical array pair according to a phased array antenna of the present invention.

FIG. 2 is an external view of a configuration in which the present invention is applied to a cylindrical phased array antenna.

FIG. 3 is a diagram of a vertical array of a conventional phased array antenna.

FIG. 4 is an external view of a conventional cylindrical phased array antenna.

[Explanation of symbols]

1, 1a, 1b Input end 2, 2a, 2b Phase shifter 3 Controller 4, 4a, 4b Vertical power supply circuit 5a, 5b Antenna element

Claims (2)

[Claims] Claim 1: Alternately 45° with respect to the beam scanning direction.
An array antenna in which antenna elements with tilted polarization planes are arranged in an array, a plurality of phase shifters connected to each of the antenna elements and capable of changing a high frequency phase to an arbitrary value, and control of each of the phase shifters. What is claimed is: 1. A polarization switching device for a phased array antenna, comprising a controller that performs the following. 2. The polarization of the phased array antenna according to claim 1, wherein the controller is configured to control each phase shifter so that the phase difference between adjacent array antennas can be set to 0, π, and π/2. Wave switching device.