JPH055203B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for monitoring phased array antennas, particularly for monitoring microwave landing systems [MLS].
The present invention relates to a phased array antenna monitoring method for monitoring the phase and level of radio waves emitted from each antenna element constituting the phased array antenna used in a microwave landing system.

[Conventional technology]

FIG. 1 is a block diagram showing an example of a phased array antenna monitoring apparatus to which this type of conventional monitoring method is applied. The phased array antenna system in this phased array antenna monitoring device includes a power divider 1 that distributes a transmission signal to a plurality of branches;
It is comprised of a plurality of phase shifters 2 connected to each branch of the power divider 1, and a plurality of antenna elements 3 that respectively radiate the outputs of these phase shifters 2 as radio waves. Further, a monitoring system for the level and phase of the transmission signal radiated from each antenna element 3 includes a coupling element 7 for extracting a part of the transmission signal, and a coupling element 7 for extracting a part of the transmission signal.
A part of the transmitted signal extracted by is converted into signals 108 and 20
a phase shifter 16 that shifts the phase of the signal 208 by 90 degrees, and a phase shift amount designation signal generator 6 that controls the phase shift amount of the phase shifter 2 at a desired time. , a receiving element 4 disposed in front of the plurality of antenna elements 3 and receiving radio waves radiated by these antenna elements 3, a distributor 8' distributing the received output of the receiving element 4 into signals 109 and 209, and a signal. 108 and 1
09 as an input, a mixer 9' as inputs of the output of the phase shifter 16 and the output of the signal 209, and detectors 5 and 5' as inputs of the outputs of the mixers 9 and 9', respectively. It consists of

When monitoring the level and phase of the radio waves output from the antenna element 3, the signal output from the coupling element 7 is divided into signals 108 and 208 by the signal distributor 8, and the signal 108 is used as one input of the mixer 9. In addition, the signal 208 is phase-shifted by 90 degrees by the phase shifter 16 and then applied as one input of the mixer 9'.

On the other hand, the receiving element 4 receives the radio waves radiated from the plurality of antenna elements 3, and the signal splitter 8' divides the output into signals 109 and 209.
9 to mixer 9 and signal 29 to mixer 9' as other inputs.

The mixer 9 synthesizes the above-mentioned input signals and outputs the signal 110 to the detector 5, and the mixer 9' synthesizes the above-mentioned input signals and outputs the signal 21 as a signal 21.
It is output as 0 to the detector 5'.

Detectors 5 and 5' each detect the level of the input signal and output it.

In this conventional phased array antenna,
Now, select one antenna element (one of the three antenna elements).
When monitoring the level and phase of the transmission signal emitted from the antenna element 3, the amount of phase shift of the phase shifter 2 connected to the other antenna element 3 is fixed during that time, and the phase shift amount of the phase shifter 2 connected to the antenna element 3 to be monitored is The amount of phase shift of the phase shifter that has been set is monotonically increased or decreased by (360 degrees)/n (n is an integer) more than n times by the phase shift amount designation signal generator 6, and Detecting AC level.

At this time, one detector 5 and the other detector 5'
The waveforms detected are all sine waves, and their phases differ by 90 degrees from each other. Therefore, the RF phase of the transmitted signal of one antenna element 3 being monitored at the same time can be determined from the phase of the detected waveform at a certain time, and the level of the transmitted signal can be determined from the AC level. In this way, the level and phase of the transmission signal of each antenna element 3 are determined.

[Problem to be solved by the invention]

In the conventional phased array antenna described above, since a sine wave is obtained as the detected waveform, the phase shift amount of the phase shifter must be rotated by 360 degrees or more, which takes processing time. In addition, with digital phase shifters that are mainly used these days, when the phase shifter fails, the output level of the phase shifter usually changes depending on the amount of phase shift, so the detected waveform is It has a distortion component. The level and phase of the transmitted signal obtained by this monitoring method then loses accuracy. In addition, the monitoring system required two channels of RF circuits (signal splitter, mixer, and lines connecting these) and detectors, which caused problems in that it was expensive and had low reliability.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for monitoring a phased array antenna that can realize an inexpensive and highly reliable phased array antenna monitoring device for a phased array antenna.

[Means to solve the problem]

The phased array antenna monitoring method of the present invention includes a branching means for branching a transmitted signal into a plurality of branching paths, a plurality of phase shifters respectively connected to the branching paths, and receiving outputs of these phase shifters and emitting them as radio waves. a phase shift amount designation signal generator that gives a signal designating the phase shift amount in each of the phase shifters to each of the phase shifters; and a receiving element that receives the radio waves. and a detector connected to the receiving element to detect and output the level of the received radio wave, and for a first time starting at a desired time and a second time starting at a time other than the first time. The phase shift amount designation signal generator transmits shifts that are 90 degrees different from each other at the first and second times to the phase shifter that is not connected to any one of the antenna elements to be monitored. The signal specifying the phase amount is respectively applied, the radio wave is received by the receiving element at the first and second times, and the output for determining the level and phase of the antenna element to be monitored is sent to the detector. It is characterized in that it is output as a detection level.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 2 is a block diagram showing an embodiment of a phased array antenna monitoring device to which the phased array antenna monitoring method of the present invention is applied, and FIG. 3 shows radio waves that are signals emitted from the plurality of antenna elements shown in FIG. is a vector diagram at a certain time,
FIG. 4 is a vector diagram of the above-mentioned radio waves received at a different time from that of FIG. 3 and in a different phase relationship.

In the embodiment shown in FIG. 2, a power divider 1 that distributes a transmission signal into required amplitudes, a plurality of phase shifters 2 that respectively control the RF phase of the signals distributed by the power divider 1, and a power A plurality of antenna elements 3 that radiate signals whose RF levels and phases are controlled to predetermined values by a distributor 1 and a phase shifter 2, respectively.
A receiving element 4 that receives the signal radiated from the antenna element 3, a detector 5A that detects the level of the signal received by the receiving element 4, and the above-mentioned phase shifter. The phase shift amount designation signal generator 6A generates and outputs a signal designating a phase shift amount of 2.

A part of the signal emitted from the antenna element 3 making up the phased array antenna is transmitted to the receiving element 4.
The signal is received by the detector 5A, and the level of the received signal is detected by the detector 5A. This level is determined when each of the phase shifters 2 to which the remaining antenna elements 3 other than the above-mentioned antenna element to be monitored are connected, when any one of the plurality of antenna elements 3 is set as the antenna element to be monitored. Measurements are taken twice: once with 90 degree phase control and once without.

In FIG. 3, the amplitude of the received wave composite vector generated by the antenna elements 3 excluding the above-mentioned monitored antenna element (one of the antenna elements 3) and output by the receiving element 4 at a certain time is b, Let b be 1, normalize by b, and let a be the amplitude of the received wave vector received by the receiving element 4 due to the radio wave output from the antenna to be monitored, and the phase difference between these two received waves is 90 (degrees) + θ ( degree), and the level detected and output by the detector 5A at this time is α.

FIG. 4 shows that the phase shift amount of each phase shifter 2 connected to the antenna element 3 except the antenna element to be monitored is determined by the phase shift amount designation signal generator 6A for the state shown in FIG. 3. It is a vector diagram when shifted by 90 degrees.

The level detected and output by the detector 5A in the state shown in FIG. 4 is assumed to be β. In the above cases, the following formula holds true.

α ² =1+a ² +2asinθ ……(1) β ² =1+a ² +2asinθ ……(2) Also, from equations (1) and (2), α ⁴ +β ⁴ −2(α ² +β ² )(1+a ² ) +2(1+a ² ) ² =4a ² ...(3) is derived. Therefore, by measuring α and β with the detector 5A and substituting them into equation (3), the relative amplitude a of the received wave from the antenna element to be monitored can be determined. and β, the received wave relative phase θ can be determined.

As described above, according to the phased array antenna monitoring method of the present invention, the relative amplitude a of the received wave from the antenna element to be monitored and the relative phase θ of the received wave can be obtained in advance. By determining the relative amplitude and phase of the received wave based on the detection level of the detector 5A and recording or storing it, it is possible to monitor how the relative amplitude and phase of each antenna element change over time. be able to.

In addition, in the embodiment shown in FIG. 2 described above, an example was given in which the radiated signal from the antenna element was received by the receiving element, but the signal extracted by the coupling element before the signal is radiated from the antenna element is Needless to say, if used, the amplitude and phase of the signal supplied to the antenna element can be monitored.

〔Effect of the invention〕

As explained above, according to the present invention, the monitoring system
Since the RF circuit and detector are one channel,
An inexpensive and highly reliable monitoring system can be used. Furthermore, in the present invention, since the phase and amplitude of the radio waves emitted by the antenna element to be monitored are determined for each phase shift amount of the phase shifter, the output level of the phase shifter connected to the antenna element to be monitored is The determined phase and amplitude are accurate even if they vary depending on the amount of phase shift of the phase shifter. Therefore, in the conventional monitoring method for phased array antennas, when the output level of the phase shifter changes depending on the amount of phase shift, the output of the detector is distorted from a sine wave, and there are large errors in the measured phase and amplitude. The present invention also has the advantage of high phase and amplitude measurement accuracy.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a phased array antenna monitoring device based on a conventional monitoring method, FIG. 2 is a block diagram of an embodiment of a phased array antenna monitoring device to which the monitoring method of the present invention is applied, and FIGS. FIG. 3 is a vector diagram of radio waves emitted from the embodiment shown in FIG. 2; 1... Power divider, 2... Phase shifter, 3... Antenna element, 4... Receiving element, 5, 5'... Detector,
6,... Phase shift amount designation signal generator, 7... Coupling element, 8, 8'... Signal distributor, 9, 9'... Mixer, 5A... Detector, 6A... Phase shift amount designation signal generator.

Claims (1)

[Claims] 1. A phased array comprising branching means for branching a transmission signal into a plurality of branching paths, a plurality of phase shifters connected to each of the branching paths, and a plurality of antenna elements each receiving the outputs of these phase shifters and radiating them as radio waves. a phase shift amount designation signal generator that gives a signal to each of the phase shifters to designate a phase shift amount in the phase shifter to the antenna; a receiving element that receives the radio waves; and a receiving element connected to the receiving element to receive the radio waves. a detector that detects and outputs the level of the radio wave transmitted, and the phase shift amount designation signal generator for a first time starting at a desired time and a second time starting at a time other than the first time. The phase shifter that is not connected to any one of the antenna elements to be monitored is provided with the signal specifying a phase shift amount that is 90 degrees different from each other at the first and second times. and receiving the radio waves at the receiving element at the first and second times, and outputting an output for determining the level and phase of the antenna element to be monitored as a detection level from the detector. Features of a phased array antenna monitoring method.