JP2947175B2 - Phased array antenna - Google Patents

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 phased array antenna characterized by a phase control method for passively tracking a moving target such as an artificial satellite or an airplane.

[0002]

2. Description of the Related Art Conventionally, when tracking a mobile object such as an artificial satellite or an airplane, when controlling using a phased array type antenna, reception is performed by switching a phase shift amount of a phase shifter of the antenna. To the higher level,
That is, tracking is performed by moving the beam in the direction of the target. Since the control of the phase shifter is usually digitized, there is a disadvantage that the beam pattern is deformed or disappears at the moment of the phase shift switching.

In the case of a transmitting / receiving radar, if it is clear that transmission and reception function normally in a pulsed manner even when the beam pattern disappears instantaneously, there is no operational problem, but in practice Miscommunication often occurred in transmission and reception.

In order to track radio waves transmitted from artificial satellites, there is a method of relatively smoothly switching by controlling a phase shifter. However, since a method of determining the level based on the level before and after switching is used, The beam dithering still has to be switched in a stepwise manner to find an error.

As described above, in the conventional phased array antenna pattern, a large number of phase shifters are used to form a pseudo beam pattern when combining received signals. However, when a phase shifter is used, Since this phase shifter is digitally controlled, there is a disadvantage that the beam disappears or collapses at the moment when the beam pattern is changed,
This is a problem to be solved. In particular, in order to perform only reception and track a continuous wave without interruption, it is strongly desired to perform beam control smoothly and without interruption.

An "antenna control system" disclosed in Japanese Patent Application Laid-Open No. 4-307381 has an arrangement shown in FIG. 3 and controls a number of phase shifters 42 of a phased array antenna 41 for satellite communication. When detecting switching to the beam with the lowest elevation angle or the highest elevation angle by beam dithering, the device 43 calculates the error between the reception level before switching and the current reception level, and switches to the low or high elevation direction. When it is determined that switching to a low or high elevation angle is necessary, the beam dithering in the elevation direction is stopped and the reception level is reduced while the beam dithering is stopped. Determines whether the beam dithering has resumed below the resumption level, and raises the elevation angle when the reception level falls below the beam dithering resumption level. By restarting the beam dithering direction, it is widened tracking range of elevation of the satellite communication phased array antenna 41.

However, in such a configuration, a common phase shifter control signal 44 is applied to each of the phase shifters 42 connected to each array 45, and they are switched at once during beam dithering. Again, the above-mentioned problem at the time of switching is not solved and remains.

[0008]

The first problem of the prior art as described above is that the transmission and reception signals are momentarily interrupted by switching stepwise by beam control, especially when the reception level is near the limit. is there. This is because radio waves transmitted from a mobile object that have a large elevation angle, such as an artificial satellite, have high line reliability, but in the case of an aircraft with a low elevation angle, the effects of multipath and transmission antenna patterns, etc. This is because the margin until the instantaneous interruption level is reached is small.

A second problem is that another beam may be generated due to a time lag of a phase shifter at the time of beam forming switching, and a radio wave in another direction is received until the beam forming is completed. Receive another radio wave at the moment of stepwise switching by beam control, and the signal / noise (S /
N) The ratio becomes worse.

[0010] Therefore, an object of the present invention is to provide a method in which even if the beam control is switched in one step, the received signal is not instantaneously interrupted, unnecessary waves are not received, and the S / N ratio is not reduced. It is an object of the present invention to provide a phased array antenna in which a beam is not lost or a beam pattern is not deformed during a transient time when a pattern is changed, and a beam characteristic is smoothly shifted even when a phase shifter is digitally controlled. .

[0011]

In order to solve the above-mentioned problems, a phased array antenna according to the present invention has a structure in which a large number of antenna elements are arranged and the signals received from the antenna elements are phase-combined with each other. A phase shifter that intervenes and shifts the respective phase shift amounts to obtain predetermined beam characteristics, wherein a phase difference is provided to the control signal for shifting the phase shift amount by providing a time difference. By providing the control means for distributing the antenna characteristics to the antennas, instantaneous interruption of the reception characteristics caused by the stepwise change in the antenna directivity is prevented.

In a phased array antenna according to another aspect of the present invention, a plurality of antenna elements are arranged, and a phase shifter is interposed between each of the received signals from the antenna elements and input to a phase synthesizer. And, in a phased array antenna for obtaining a predetermined beam characteristic by shifting the phase shift amount of each of the phase shifters, a delay device is provided between the phase shifter and the phase shift combiner, By providing a means for inputting with a time difference so that signals at the time of shifting the phase shift amount are not simultaneously input to the phase shift synthesizer, a plurality of beam characteristics are simultaneously maintained without instantaneous interruption. It is configured.

Here, each of the plurality of delay units has a fixed or variable delay time, and the delay time is also set to a transient time for changing the phase shift of the phase shifter.

[0014]

FIG. 1 shows an embodiment of the present invention.
Referring to FIG. 1, the antenna according to the present embodiment includes a plurality of receiving antenna elements 1, an amplifier 2 connected to the antenna element 1, a distributor 3 connected to the amplifier 2, and a distributor 3 connected to the amplifier 3, respectively. Connected phase shifter 4
Or 5, a phase shift controller 6 connected to all of the phase shifters 4 or 5, a synthesizer 7, an external controller 8,
And a receiver 9.

Until the radio waves received from the antenna element 1 are input to the synthesizer 7, the received radio waves are amplified and distributed as they are, and the phase is shifted.

Mobile objects such as satellites and airplanes (not shown)
Are received by the receiving antenna element 1 in which a large number of common unit antennas are arranged on one plane,
The power is supplied to the waveguide or the coaxial cable, and the amplifier 2 amplifies the power to compensate for the distribution loss and the cable loss. The amplification amplifier 2 also has a filter function for cutting unnecessary radio waves. Each of the amplified received signals is distributed by the distributor 3 to other receiving units in addition to the combiner 7 shown in the figure. The number of distributions matches the number of arrivals of radio waves received simultaneously. The divided signals are input to the phase shifters 4 and 5, respectively, and output after being phase-shifted. The shift amount of the phase shift is determined by a command signal of the phase shift controller 6.

The signals output from the phase shifters 4 and 5 are both phase-combined by the combiner 7, and unnecessary signals are cut as antiphase inputs, and only necessary signals are input in phase and received as received signals. Will be synthesized. The reception signal 11 output from the synthesizer 7 is received by the receiver 9 that passes a designated frequency, and an output 15 of the reception signal 11 and an output of the reception level 12 are obtained. The reception level 12 is
The input level is input to the external controller 8, the immediately preceding input level is compared with the current input level, it is determined whether or not tracking is necessary, and if necessary, a phase shift control reference for forming the next changed beam pattern is used. A signal 13 is output.

An error signal 14 for operating the phase shifters 4 and 5 at a predetermined time difference so as not to operate at the same time.
Is output to the phase shift controller 6, and the phase shifters 4 and 5 are controlled by the command signal output from the phase shift controller 6.
The phase shifter 4 and the phase shifter 5 may be a common one having no difference in performance. Here, for example, swinging a beam necessary for tracking is handled as the phase shifter 5.

The control signal output to each of the phase shifters 4 and 5 indicates the value of switching to the phase shifters 4 and 5, and has the same operation as that of a normal phased array type antenna. It is. The error signal 14 controls the operation time of the phase shifters. At the same time, the phase shifters 4 and 5 are switched so that each of the phase shifters 4 and 5 does not change significantly.
Phase shift control is performed with a time difference so that 5 is sequentially switched. For this reason, the beam pattern can form a shape necessary for tracking while maintaining a stable shape, and instantaneous interruption does not occur.

For example, when the phase shift control reference signal 13 is input to the phase shift controller 6 so as to change the beam at a predetermined angle, all the phase shifters 4 and 5 change the beam at the predetermined angle. Is controlled by specifying the amount of phase shift so that all the phase shifters are not simultaneously shifted. For example, immediately after the phase shifter 4 is controlled by the phase shift shift, , A control signal is applied so that the phase shifter 5 is subjected to phase shift control.

In this way, the influence of the transient period is reduced, so that the beam pattern does not suddenly change, but also the beam characteristics including many phase shifters 3 and other phase shifters 5. Even if the phase shift control is performed stepwise in order to settle to the next changed beam characteristic through the intermediate characteristic from the beam characteristic, the change can be made smoothly.

The phase shift controller 6 gives a control signal for controlling the phase shifter, not simultaneously, but with a time difference. The error signal 14 includes a control signal for setting a magnitude of the time difference as well as for distributing the control signal to each phase shifter so as to provide a time difference.

Without switching the phase shifters 4 and 5 simultaneously,
With respect to the control reference signal 13 corresponding to the command angle of the beam,
By providing a time difference to each of the phase shifters 3 and 5 as an error signal 14, a means for smoothly changing beam shaping is provided. The error signal 14 is calculated by the external controller 8 from the tracking error angle and the reception level in order to not only obtain the error angle required for tracking but also improve the tracking performance, and outputs the error signal to each phase shifter. Is what is done.

According to the present embodiment, the beam characteristics before the change and the beam characteristics after the change are mixed at a certain time. Therefore, the reception levels of the two are compared to determine the beam change angle. Also available.

In the block diagram of FIG. 2 showing another embodiment of the present invention, the phased array antenna has parts common to those of the embodiment of FIG. 1, namely, an antenna element 1, an amplifier 2, a distributor 3, and a combiner. 1, apart from the receiver 9 and the external controller 8, the phase shift amount setting unit 27, the delay amount distribution circuit 26, the first to n-th delay units 20 and 21 , 22,..., 23, 24, 25.

Between the phase shifters 4 and the combiner 7, first to n-th delay units 20, 21, 22,... In which the delay amount is set by a control signal from the delay distribution circuit 26, respectively.・
23, 24 and 25 are interposed.

The phase shift amount setting section 27 distributes and sets the phase shift amount of each phase shifter 3 based on the phase shift control reference signal so as to obtain a predetermined beam characteristic. At the same time.

The delay amount distribution circuit 26 sets the delay amounts of the first to n-th delay units 20 to 25 based on the error signal 14. For example, the delay amount of the second delay unit 21 is larger than the delay amount of the first delay unit 20 by the delay time difference Td, and the delay amount of the third delay unit 22 is further larger than that of the second delay unit 21. Td, thus increasing the nth delay 2
Until the delay time reaches 5, the delay amount of the (n−1) th delay unit 24 becomes T
It is set larger by d.

This delay time difference Td corresponds to a transient period during which the phase shift of the phase shifter 4 is changed. Therefore, even if the shift amount is set for each phase shifter 3 at the same time, it is not input to the combiner 7 at the same time, and the received signals during the unstable transition period are simultaneously generated and combined. Since the signal is no longer input to the mixer 7, a large drop does not occur in the synthesized wave obtained by the synthesizer 7. Further, since the delay amount is distributed and set so as to be equivalent to a case where the change of the beam characteristic is not applied to all the antenna elements 1 at once but is sequentially applied to each antenna element 1, the beam characteristic is changed smoothly. .

According to the present embodiment, the delay line may be used so that the delay amount difference of the delay unit is set to a difference of exactly one wavelength or several wavelengths of the reception frequency.

In the present embodiment, the first to n-th
The delay time of the delay units 20 to 25 is variably set and used. However, the delay time Td can be fixed and fixed. In this case, the distribution for variably setting the delay time can be used. The circuit 26 need not be provided.

Furthermore, according to the present embodiment, only the addition of the first to n-th delay units having a variable or fixed delay amount is required in comparison with the conventional circuit configuration. There is convenience that can be solved with a simple additional configuration.

[0033]

As described above, according to the phased array antenna of the present invention, instantaneous interruption at the time of beam shaping change is eliminated, a continuous signal can be received, and the beam is partially deformed. Reception can be performed, and all the problems described above are solved.

[Brief description of the drawings]

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

FIG. 2 is a block diagram showing a second embodiment of the present invention.

FIG. 3 is a block diagram showing a conventional antenna control method.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 antenna element 2 amplifier 3 distributor 4, 5, 42 phase shifter 6 phase shift controller 7 combiner 8 external controller 9 receiver 43 antenna controller 45 array 20 to 25 delay unit 26 delay amount distribution circuit 27 phase shift Shift amount setting section

Continuation of the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) G01S 7/00-7/42 G01S 13/00-13/95 H01Q 3/26-3/42

Claims (5)

(57) [Claims] A plurality of antenna elements are arranged, and a phase shifter intervenes until a received signal from the antenna elements is phase-combined with each other. In a phased array antenna for obtaining characteristics, control means for providing a time difference to a control signal for shifting the phase shift amount and distributing the control signal to the phase shifter is provided.
By changing the antenna directional characteristics in a step
A phased array antenna which prevents instantaneous interruption of reception characteristics caused by the phased array antenna . 2. A phase shifter intervenes between a plurality of antenna elements arranged and a received signal from each of the antenna elements being input to a phase synthesizer, and a phase shift amount of each of the phase shifters. In the phased array antenna which obtains a predetermined beam characteristic by shifting the phase shifter, a delay unit is provided between the phase shifter and the phase shift combiner, and the signals at the time of shifting the phase shift amount are simultaneously shifted. By providing a means for inputting with a time difference so as not to be input to the phase combiner, multiple beam characteristics can be simultaneously maintained without interruption.
Phased array antenna, characterized in that the lifting
Na . 3. The phased array antenna according to claim 2, wherein the delay time of the delay unit is fixed. 4. The phased array antenna according to claim 2, wherein the delay time of said delay unit is variable. 5. The phased array antenna according to claim 1, wherein each delay time of the plurality of delay devices is a transient time of a phase shift change of the phase shifter.