JPH0283478A - Antenna apparatus - Google Patents

Abstract

PURPOSE:To automatically adjust a phase corresponding to the frequency selection of an antenna system by providing a circuit for detecting the demodulation output signal of a receiver at the time of output of calculate the phase difference between a reference signal system and an error signal system and correcting phase difference. CONSTITUTION:A signal generator 19 imparting receiving frequency for performing phase adjustment and a signal distributor 18 are provided and one system is connected to an error signal system by a coupler 15 through an attenuator 17 and a phase shifter 16 and, in the other system, the output of a polarizer 4 is coupled with a reference signal system by a coupler 14. The phase correction circuit 40 consisting of a phase difference detection circuit 20 and a variable phase shifter 21 of the reference and error signal systems is provided. By this method, the phase adjustment of an antenna system can be automatically performed at arbitrary frequency.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an antenna device for tracking a target in satellite communication or the like.

[Conventional technology]

FIG. 5 is a block diagram showing a conventional monopulse tracking antenna for receiving circularly polarized waves. In the figure, ■ is an antenna,
2 is a mode coupler, 3 is a polarization converter, 4 is a polarization demultiplexer, 5
a, 5b are low noise amplifiers, 6a, 6b are mixers, 7 is a phase detector, 8 is a voltage controlled oscillator, 9 is a reference oscillator, 10
is a variable phase shifter, 11.12 is a phase shifter, 13 is a 90
'It is a phase shifter.

Next, the operation will be explained. FIG. 5 is a block diagram of a monopulse tracking antenna using high-order mode signals.

When the antenna 1 deviates from the target, the radio waves received by the antenna 1 generate higher-order mode signals in addition to the fundamental mode signal. This higher-order mode signal is transmitted to the mode coupler 2
is detected and supplied to the low noise amplifier 5b as an error signal.

On the other hand, the fundamental mode signal passing through the mode coupler 2 is converted into a linearly polarized wave by the polarization converter 3, and is supplied to the low noise amplifier 5a via the polarization splitter 4.

The fundamental mode signal is frequency-converted by mixers 6a and 6b as a reference signal and the higher-order mode signal as an error signal, respectively. In the basic mode signal system, a phase locked loop is constructed by detecting the phase of a reference signal using a signal from a reference signal oscillator 9 using a phase detector 7, driving a voltage controlled oscillator 8, and supplying the signal as a local signal to mixers 6a and 6b. are doing. On the other hand, the error signal system uses a variable phase shifter 10 to shift the output of the reference signal oscillator 9 by the phase difference between the reference signal system and the error signal system and supplies it to the phase detector 11. The output is shifted in phase by 90° by a phase shifter 13 and is applied to a phase detector 12 .

By performing orthogonal detection in this manner, DC error signals corresponding to the two drive axes AZ and EL of the antenna are obtained.

In monopulse tracking, the route of the reference signal system and the route of the error signal system of the tracking signal received by antenna 1 are different, so when detecting the error signal with the phase detector, the absolute distance from the antenna to the detector is different. The phase amount differs between the reference signal system and the error signal system, and unless this is corrected and detected, a correct error signal output cannot be obtained.This correction amount is provided by the variable phase shifter 10.

By the way, this phase amount changes depending on the reception frequency (the phase characteristics of the device), so radio waves are transmitted through collimation, etc., and the radio waves are received and adjusted. Therefore, in an antenna that selectively receives multiple frequencies, it is necessary to measure the phase amount at each frequency, store it all in the variable phase shifter 10, and select and output the phase amount according to the frequency selection. There is.

[Problem to be solved by the invention]

Since the conventional monopulse tracking antenna device is configured as described above, it is necessary to measure and store the number of phase amounts corresponding to the frequency used, and it is also necessary to measure and store the amount of phase in the number corresponding to the frequency used. If the characteristics change, there are problems such as the need to transmit radio waves through collimation etc. and rememorize all the phase amounts.

This invention was made to solve the problems of the conventional ones as described above, and for arbitrary frequency selection,
The purpose of this invention is to obtain an antenna device that can measure the phase amount of a receiving system and perform automatic phase adjustment by manually inputting a reference calibration signal.

[Means to solve the problem]

The antenna device according to the present invention is provided with a circuit for inputting a reference calibration signal of a predetermined frequency into the reference signal system and error signal system of the power feeding device in order to measure the phase amount of the receiving system, and when the signal is input from this circuit. Automatic phase adjustment is performed by detecting the demodulated output signal of the receiver, determining the phase difference between the reference signal system and the error signal system, and providing a phase correction circuit that corrects the error signal by the phase difference. be.

[Effect]

In the present invention, since the phase amount to be adjusted is determined by inputting the reference calibration signal in automatic phase adjustment, automatic phase adjustment can be performed for any frequency without having to memorize it in advance.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an antenna device according to an embodiment of the present invention,
In the figure, the same reference numerals as in FIG. 5 indicate the same thing.
9 is a signal generator that provides a signal of the reception frequency to be phase adjusted; 18 is a signal divider for distributing this signal into two systems; the L system passes through an attenuator 17 and a phase shifter 16, is coupled to the error signal system. The other system is directly coupled to the reference signal system of the polarization splitter 4 output by a coupler 14. Reference numeral 30 denotes a calibration signal supply circuit consisting of the circuits 14 to 19 described above. 20 is a phase detector 11
．． 12 is a phase difference detection circuit that receives the DC error signal output and calculates the phase difference between the reference signal system and the error signal system; 21 is a variable phase shifter that sets a value equal to the calculated phase difference; is a phase correction circuit consisting of the phase difference detection circuit 20 and the variable phase shifter 21.

Next, the operation will be explained. The reference calibration signal is provided by adjusting the level of the error system with respect to the reference system using an attenuator 17 so as to give a certain specified value to the error signal. Further, as for the phase amount, for example, the phase is adjusted by a phase shifter 16 so that the reference system and error system signals are in the same phase. This error signal is as shown in FIG.

Assuming that there is a phase difference between the reference system and the error system after the reference calibration signal input point, the error signal output obtained by phase detection with the phase setting amount of the variable phase shifter 21 being O is as shown in FIG. The amount of phase difference can be obtained as φi.

When tracking the target, the signal generator 19 is turned OFF and the phase amount φ8 is applied to the variable attenuator 21 for phase detection, thereby correcting the phase difference and generating an error signal in the same way as shown in FIG. can be detected correctly.

In addition, in the above embodiment, an example was shown in which automatic phase adjustment is performed by changing the phase amount of the reference signal given to the phase detector, but as shown in FIG. 4, the phase amount given to the phase shifter 21 is always O. , a coordinate conversion circuit 22 may be provided which performs coordinate conversion processing on the output of the DC error signal by the detected phase difference based on the signal of the phase difference detection circuit 20. The output of the coordinate transformation circuit performs the following coordinate transformation.

Furthermore, the antenna 1° mode coupler 2. Polarization converter 3. Due to the phase characteristics due to the polarization splitter 4,
If there is a difference, automatic phase adjustment can be performed by measuring this phase characteristic in advance and correcting φ8.

In other words, the phase difference (φll) when input from the reference calibration circuit
) to φ = φ "wings + φR (φFll: phase difference of the reference calibration system (up to the output point of the coupler), φR: phase difference of the receiving system (after the low noise amplifier)) Phase difference when receiving radio waves from the target object (φ,)φ,=
φF, +φ8 (φ7.: Phase difference between the target object receiving system (up to the coupler output point)) Phase difference characteristics (ΔφF) between the reference calibration system and the target object receiving system that are actually measured in advance Δφ, = φ7. −φ□ Automatically correct phase! (φA) φ, =φ, =φ8+Δφ.

〔Effect of the invention〕

As described above, according to the antenna device according to the present invention,
A reference calibration signal input circuit and a phase difference detection and correction circuit are provided, and the configuration allows automatic phase adjustment at any frequency when calibration is required, so there is no need to memorize a large number of phase quantities. Since there is no need for collimation equipment or the like, the device can be made at low cost and has the advantage of being highly accurate.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an antenna device according to an embodiment of the present invention, FIG. 2 is a diagram showing an example of an error signal given as a reference constituent signal, and FIG. 3 is an example of an error signal detected by a phase detector. FIG. 4 is a block diagram showing another embodiment of the present invention, and FIG. 5 is a block diagram showing a conventional antenna device. In the figure, 14.15 is a coupler, 16 is a phase shifter, and 17
is an attenuator, 18 is a signal distributor, 19 is a signal generator, 20
21 is a variable phase shifter, 22 is a coordinate conversion circuit, 30 is a calibration signal supply circuit, and 40 is a phase correction circuit. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] (1) One or more targets at multiple frequencies
In an antenna device that selects one frequency and tracks it using a monopulse method, the calibration signal supply circuit supplies a reference calibration signal having a predetermined phase and amplitude relationship to a reference signal system and an error signal system of a power feeding device; It is equipped with a phase correction circuit that detects the received demodulated signal with respect to the calibration signal, calculates the phase difference between the reference signal system and the error signal system, and corrects it, and automatically executes phase adjustment according to frequency selection. Characteristic antenna device.