JPS5844220B2 - Transmission polarization characteristic measurement method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for measuring the transmission polarization characteristics of an antenna, that is, the elliptical polarization coefficient and tilt angle, with high precision using a phase amplitude detection method.

A conventional device of this type is shown in FIG.

In FIG. 1, 1 is a carrier signal generation circuit including a transmitter, 2 is a polarization matching circuit for measurement, and polarization demultiplexer 3
, 90° retardation plate 4, 180° retardation plate 5, and rotary joints 6a, 6b, and 6c.

Reference numeral 7 denotes an antenna to be measured, which includes a group demultiplexer 8, a -order radiator 9, a sub-reflector 10, a main reflector 11, and the like.

On the other hand, 12 is a polarization reference antenna, and the same polarization matching circuit 2 as described above is attached to its feeding portion, and the carrier wave signal generation circuit 1 is also connected thereto.

A transmission main polarization signal 13 is transmitted from the antenna under test 7, and
A transmission main polarization signal 14 is transmitted from the polarization reference antenna 12 toward the satellite reception antenna 15, and each return signal 18 or 19 that has passed through the satellite repeater 16 and the satellite transmission antenna 17 is transmitted to the antenna under test 7. Each amplitude voltage is received using reception system equipment and detected by an amplitude detection circuit 22 including a receiver connected to one of the reception terminals 21 of the reception polarization conversion circuit 20.

Next, the operation will be explained.

First, remove the transmission polarization conversion circuit of the antenna under test 7, install the polarization matching circuit 2 in its place, connect the carrier signal generation circuit 1, and polarize the antenna so that the output voltage of the amplitude detection circuit 22 becomes zero. Wave matching circuit 90° retardation plate 4 and 180
0 Rotate the phase difference plate 5.

The mechanical rotation angles of both retardation plates at that time are read, and the elliptical polarization ratio of the synthetic skin of the antenna to be measured 7 and the satellite receiving antenna 15 is determined.

This result is defined as the measurement value a. When the polarization matching circuit 2 is attached to the polarization reference antenna 12, the carrier signal generation circuit 1 is connected, and the same measurement as above is performed, the polarization reference antenna 12
and the elliptical polarization coefficient of the synthetic leather of the satellite receiving antenna 15.

Let this result be the measured value.

Furthermore, after mechanically rotating the polarization reference antenna 12 by 90 degrees around the beam axis of the antenna, similar measurements are performed to obtain the elliptical polarization coefficient. reversed version and satellite receiving antenna 15
The flattened polarization characteristics are required.

Let this be measured value C.

As a result, from the measured value C, the polarization reference antenna 1
2 is removed, and the measured value d of the elliptical polarization coefficient of the satellite receiving antenna 15 can be obtained.

Next, a measured value e of the elliptical polarization coefficient of only the antenna to be measured 7 can be obtained from the measured value d and the measured value a.

The vector relationship between these measurements is shown in FIG.

In FIG. 2, 23 is a measured value a of the composite elliptical polarization coefficient of the antenna to be measured 7 and the satellite receiving antenna 15. In FIG.

Further, 24 and 25 are the composite elliptical polarization coefficients of the polarization reference antenna 12 and the satellite receiving antenna 15, and the measured values and the measured values before and after 900 mechanical rotations of the antenna beam axis center of the polarization reference antenna 12. It is C.

From the three vectors 23, 24, and 25 measured in this way, 26, which is the difference between 24 and 25, represents the elliptic polarization factor of polarization reference an divided by 12, and the sum of 24 and 25. 2γ, which is 100, is the measured value d of the elliptical polarization coefficient of the satellite receiving antenna.

Furthermore, 28, which is the difference between 23 and 27, is the antenna under test 7.
This shows the measured value e of the elliptic polarization index.

As mentioned above, in measuring transmission polarization characteristics using the conventional method, (1) the transmission polarization conversion circuit, which is a part of the antenna device under test, must be removed and the polarization matching circuit 2 installed there; This means that the work requires the assistance of a dog.
(2) It takes a considerable amount of time to rotate the 90° retardation plate 4 and the 180° retardation plate 5 to make the return signals 18 and 19 zero; (3) the mechanical rotation angle of the retardation plate; (4) Furthermore, in order to obtain the overall elliptical polarization factor that includes all the components of the antenna device under test, it is necessary to use the value obtained in this measurement and the transmission polarization conversion circuit measured separately. It has drawbacks such as low accuracy because it requires vector synthesis of the elliptical polarization coefficients of .

The present invention was made in order to eliminate the drawbacks of the conventional technology as described above, and it transmits a carrier wave signal and a carrier wave suppression modulation signal as radio waves having two orthogonal polarization planes to a satellite. To provide a transmission polarization characteristic measurement method that can easily measure with high accuracy in a short time by detecting the phase and amplitude of a carrier component and a carrier suppression modulation signal component in a signal reflected from a carrier. The purpose is to

The present invention will be described in detail below using the drawings.

FIG. 3 shows an embodiment of the present invention, in which numeral 29 is a carrier wave and carrier suppression modulation signal generation circuit including two transmitters, 30 is a changeover switch, and 031 is an antenna device to be measured, which is divided into groups. This is an entire antenna transmission system including a wave transmitter 8, a -order radiator 9, a sub-reflector 10, a main reflector 11, and a transmission polarization conversion circuit 32.

33 and 34 are orthogonal circularly polarized wave transmission terminals of the antenna device under test.

Reference numeral 35 denotes a transmission polarization reference antenna device comprising a polarization reference antenna 12 and a transmission polarization conversion circuit 36 attached to its feeding portion.

A carrier wave and a carrier wave suppression modulation signal generation circuit 29 are selectively connected to the orthogonal circular polarization transmission terminals 37 and 38 of the transmission polarization reference antenna device 35 by a changeover switch 30 .

39 and 40 are radio waves transmitted from the antenna device under test 31 and the transmission polarization reference antenna device 35 toward the satellite receiving antenna 15, and 41 and 42 are radio waves that pass through the satellite repeater 16 and the satellite transmitting antenna 17, respectively. This is a radio wave that is reflected back.

These radio waves are received using the reception system equipment of the antenna device under test 31, and the phase amplitude detection circuit 4 includes a receiver connected to one of the reception terminals 21 of the reception polarization conversion circuit 20.
3, it is processed.

A detailed configuration example of the carrier wave and carrier wave suppression modulation signal generation circuit 29 is shown in FIG. 4a.

51 is a carrier wave generator, 52 is a modulation square wave generator, 53
is a carrier suppression modulator, and is constituted by, for example, a 100% amplitude modulator or a two-phase phase modulator.

54 and 55 are frequency converters, 56 is a common local oscillator, and 57 and 58 are transmitters.

Reference numerals 59 and 60 are the output terminals of this circuit, which are connected to the orthogonal circularly polarized wave transmitting terminal of the antenna, and the waveforms there are shown in FIG. The figure shows the carrier wave suppression modulation signal ft±If, which is the waveform of the output terminal 60, as a function of time and frequency, respectively.

Note that C in the same figure shows the situation when a part of b is added to a, which will be described later.

A detailed configuration example of the phase amplitude detection circuit 43 is shown in FIG.

61 is a terminal connected to one of the receiving terminals of the antenna, into which a signal as shown in FIG. 5C is input.

62 is a receiver, 63 is a frequency converter, 64 is a local oscillator, 65 is a first intermediate frequency amplifier, 66 is a second intermediate frequency converter, and a narrow band filter 67 separates only the carrier wave, which is the main polarization component. After being detected, [reference signal detector 68
->Lude filter 69 -> voltage controlled oscillator 70], forming a phase locked loop and an automatic gain control loop.

The carrier suppression modulation signal, which is a cross-polarized component, is phase-detected by phase detectors 71 and 72 based on the output of the reference signal detector 68 and the signal passed through the 90° phase shifter 73, and then Synchronous detectors 74 and 75 perform clock detection based on the clock output of clock pulse regenerator 76, respectively, and obtain signals at output terminals 77 and 78.

These two outputs are the X-axis component and the y-axis component of vector coordinates, the length of the vector indicates the elliptical polarization, and the vector direction indicates twice the Tittle angle. It consists of a Y recorder, etc.

Next, the operation will be explained.

First, the carrier wave and the carrier wave suppression modulation signal circuit 29 are connected to the orthogonal polarization transmission terminals 33 and 3 of the antenna device under test 31.
4, and transmits the carrier wave shown in FIG. 5a with main polarization, for example, left-handed circular polarization, and the carrier wave suppression signal shown in FIG.

Only the main polarization component of this signal is received by the satellite receiving antenna 15, but at this time, the signal includes a cross-polarized component signal caused by imperfections in the polarization characteristics of the antenna under test 31 and the satellite receiving antenna 15. is added and the signal wave becomes as shown in FIG. 5C.

This signal directly passes through the 5-satellite repeater 16 and the satellite transmitting antenna 17, and becomes a return signal to the antenna device under test 3.
Since it is received by the receiving system of 1, the phase amplitude detection circuit 4
3 detects the phase and amplitude of the carrier suppression modulation signal leaking into the carrier wave, an elliptical polarization signal is obtained by combining the transmission polarization characteristics of the antenna device under test 31 and the reception polarization characteristics of the satellite receiving antenna 15. The ratio and tilt angle are determined.

This measured value corresponds to the above-mentioned measured value a.

Next, when the changeover switch 30 is switched to connect the carrier wave and carrier suppression modulation signal generation circuit 29 to the transmission polarization reference antenna device 35 and the same measurement as above is performed, the transmission polarization reference antenna device 35 is A combination of the transmission polarization characteristics and the polarization characteristics of the satellite receiving antenna 15 can be obtained.

This measured value corresponds to the above-mentioned measured value.Furthermore, after mechanically rotating the transmitting polarization reference antenna device 35 by 90 degrees around the antenna beam axis, similar measurements are performed to obtain the polarization. The wave characteristics are a combination of the polarization characteristics of the transmitting polarization reference antenna device 35 with the polarity reversed and the polarization characteristics of the satellite receiving antenna 15.

This measured value corresponds to the measured value C mentioned above.

In this case, when the polarization reference antenna device 35 for transmission is mechanically rotated, it is sufficient to rotate only the transmission polarization conversion circuit 36 by 900 rotations if the polarization characteristics of the polarization reference antenna 12 are good.

Therefore, from these three measured values, the vector relationship shown in FIG. 2 holds true as in the case described above, so that the transmission polarization characteristic of only the antenna device under test 31 can be determined.

As is clear from the above explanation, according to the method of the present invention, by performing electrical signal processing with high precision, it is possible to measure the transmission elliptic polarization of the antenna to be measured extremely precisely and in a short time. .

Therefore, the present invention makes it possible to accurately measure high-performance large-diameter antennas for satellite communication with an axial ratio of 0.2 dB and a cross-polarization discrimination of 40 dB, which has been extremely difficult in the past.

As explained above, by transmitting the carrier suppression modulation signal with the main polarization as the carrier wave and the cross polarization, and detecting the phase amplitude of the carrier suppression modulation signal component of the cross polarization that leaks into the main polarization with respect to the carrier wave. Since it is possible to measure the elliptical polarization coefficient with high accuracy, it is extremely useful for determining the polarization performance of large-diameter antennas for satellite communications.

[Brief explanation of drawings]

Figure 1 is a configuration diagram showing an example of a measurement device using a conventional measurement method, Figure 2 is a vector relationship diagram when determining the elliptical polarization coefficient of only the antenna system under test from measurement results, and Figure 3 is FIGS. 4a and 4b are block diagrams showing detailed configuration examples of circuits used in the measurement method of the present invention. FIGS. FIG. 3 is a waveform diagram showing an example of a signal handled by the measurement method.

Claims (1)

[Claims] 1. Alternately connect a carrier wave and a carrier suppression modulation signal to each transmission main polarization terminal and each cross polarization terminal of a polarization reference antenna device and a measured antenna device that can be mechanically rotated by 90 degrees around the beam axis. At the same time, the carrier wave component and the carrier wave suppression modulation signal component are separated from each other from the main polarized reception signal reflected from the test antenna facing these antenna devices, and the phase and amplitude of the two components are determined. A transmission polarization characteristic measuring method characterized in that the transmission polarization characteristic of the antenna under test is determined using a vector obtained by detection.