JPS60192271A - Neighborhood electric field measuring device - Google Patents

Abstract

PURPOSE:To correct errors in amplitude and in phase of a transmitter-receiver system caused by temperature change, etc., in measuring environment during measurement, by detecting the hourly variation of signals distributed at the feeding point of an antenna to be measured. CONSTITUTION:A probe 27 is stopped at a prescribed location and outputs distributed at the feeding point of an antenna 23 to be measured are connected to a receiver 31 by means of a switching device 30, and then, recording in a CPU32 is performed by using the amplitude and phase of signals are reference signals. Then, by continuously running the probe 27 in the direction of y-axis and operating the switching device 30 at short time intervals, the quantity of variation of the outputs at the feeding point from the reference signals is calculated and sent to a control device 24 and the quantity of variation is corrected by a variable phase shifter 22 and variable attenuator 21. On the other hand, when the location of the probe 27 detected by a probe location detecting device 29 coincides with a measuring point, the output signal of the probe 27 is connected with the receiver 31 and data are accumulated in a data accumulating device 35. The remote radiating directivity of the antenna to be measured is found by using the data.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a near-field electric field measurement device that measures an electromagnetic field in the vicinity of an antenna, and particularly to a method for correcting amplitude one-phase fluctuations in a transceiver system.

[Technical background of the invention and its problems]

Plane scanning near electric field measurement will be explained. The plane scanning type near-field electric field measuring device has an antenna to be measured 1. as shown in FIG. 14 transmitters feeding power to the antenna under test 12. Probe 3 for measuring the electric field near the antenna to be measured 1. It consists of a device 4 for driving this probe, a receiver 5, and a device 6 for accumulating and processing measurement data.

In near-field electric field measurement, two probes with different characteristics are used. First, one probe is used to measure the amplitude and phase of the electric field near each measurement point on a two-dimensional plane, and then a similar measurement is performed using a probe with different characteristics in place of the probe. Using the measured data values, the processing device 6 performs calculation processing such as Fourier transform to determine the far radiation directivity and gain of the antenna 1 to be measured.

In this measurement, it is necessary to accurately measure the amplitude and phase of the electric field near the antenna under test. However, in an actual measurement system, temperature changes in the measurement environment and frequency fluctuations in the transmitter always occur in the transmitter/receiver system, so that a one-amplitude phase error due to the above fluctuations occurs in the probe reception signal. The larger the aperture of the antenna to be measured and the higher the frequency, the greater the number of measurement points and the longer the time required for dill determination.

For example, when the aperture is 100λ or more, the total measurement time ranges from several hours to more than ten hours. Therefore, during this measurement time, the phase of the received signal due to temperature changes and frequency fluctuations in the transmitter/receiver system that occur on the received signal described in (g) changes by several degrees (from several tens of degrees). Even if we consider the far-field directivity of the antenna under test using data including
4A 1. The directivity cannot be matched and an error exceeding the allowable value occurs. Generally, in order to accurately set the directivity to a level of about -30 dB, it is necessary to suppress the total measured phase error to within about 30 dB. From this, it can be seen that the amount of error occurring on the received signal shown above is a problem.

Also, if the aperture of the antenna under test is the same or larger than the scanning frame, the near-field data necessary to obtain the desired far-field directivity can be measured in all the necessary areas with one constant strain. Can not. For this purpose, the measurement area of the near electric field of the antenna under test is divided into two or more parts, and from the data in each divided area, the near electric field measurement data necessary to obtain the desired far-field directivity is created. There is a need.

In this case, the problem is how to connect the divided data. This is because, as mentioned earlier, even during the time it takes to acquire data in the 1-division t11 region, temperature changes in the measurement environment and frequency fluctuations in the transmitter system occur in the transceiver system, resulting in amplitude and phase errors in the probe reception signal. occurs.

The same thing can be said about the times acquired in each divided area. Therefore, the measured values of the two regions connecting the data are also different values. Therefore, even if the far field is determined from data containing errors in the received signal obtained by the method described above, accurate far field directivity cannot be determined.

Conventionally, in order to solve these problems, the vehicle is run as shown in FIG. 2 and data is collected every Δy. Next, △X in the X-axis direction
11 and perform the same measurements as above.

This is done for all measurement points on the X axis.
yI scanned first after all axial measurements were completed
iI111 direction and direct firing direction (X-axis direction), and y
Scan over 12 on the center of the axis. A method is used in which this measured value is compared with the first measured value on a two-dimensional plane to correct changes in the received signal caused by changes in temperature or the like.

This method assumes that there is no change in amplitude or phase of the transmitter/receiver system during the measurement time of continuous scanning on y'tll. The force is 1, and in the actual measurement system, the delayed running force f on the y-axis is
It takes more than a few minutes. Furthermore, as the foot antenna to be measured becomes a large aperture antenna and the frequency used increases, the number of measurement points and the length of the foot to be measured increase, so the measurement time takes longer than the several minutes or more described above. During this period, the transmitter/receiver system undergoes a phase change of one width (one width) due to temperature changes around the foot measuring device, and its value also changes by more than 30, which is the allowable value shown above, during one scan. There is also.

When measuring by dividing the near electric field scanning plane, the conventional method can correct the divided fixed area, but cannot perform J correction between the divided scanning areas. Therefore, in the conventional method, the measurement result is insufficient for the near-field measurement, which requires measurement results with the same accuracy.

[Object of the Invention] The present invention has been made in view of the above-mentioned points.
A near-field electric field measurement device that corrects phase errors during measurement, eliminates the i, q difference that occurs in the far-field directivity of the antenna to be measured due to the above-mentioned measurement errors, and improves the accuracy of the obtained directivity. The purpose is to provide.

[Summary of the invention]

The present invention inserts a variable attenuator and a variable phase shifter between the transmitter and the antenna under test, divides the signal into two at the feeding point of the antenna under test, and connects the antenna under test to one side. A mixer is connected to the other end, and this signal and the signal received by the probe passed through the mixer are switched between each other, and the obtained signal is distributed at the feeding point of the antenna under test. The change in the signal over time is detected, and the detected change amount is corrected for the variable attenuator and the variable phase shifter.

〔Effect of the invention〕

It is possible to correct during measurement the error signal due to near-field warfare caused by phase fluctuations in the width of the transceiver system caused by temperature changes in the measurement environment. It is possible to put

Furthermore, the above-mentioned error signal between the respective divided regions obtained by dividing the near electric field scanning plane can also be corrected during measurement. Therefore, the present invention is effective for measurements that require highly accurate measurement results.

There is no need for measurements to calibrate system variations after all measurements performed in the conventional method, and there is also no need for corrections for all two-dimensional measurements after measurements.

[Embodiments of the invention]

An embodiment of the present invention is shown in Figure 3.

The present invention includes a transmitter 20, an antenna to be measured 23, and a variable attenuation for calibration inserted between them. ? 321 and.

There is a variable phase shifter 22, which is 1ttlJ ftflll T
24, mixer 25, scanning frame 26, probe 27, probe, squirrel @ device 28, probe position 1: production device 29, signal switching device 30, receiver 3
1, a CPU 32, and a data storage device 33.

A specific example will be explained below.

In FIG. 3, the signal distributed at the feeding point of the antenna under test is connected to a mixer 25-b.

The signal after passing through this mixer 25-b includes IF, L
O(i) is flowing.The frequency of this I F is sufficiently lower than that of the LO multiplied signal transmission signal RF.

Furthermore, the cable carrying this signal is fixed so that there are no moving parts.

The signal distributed at the feeding point of the antenna under test.

Observing the output signal after it has been traced to the receiver 31, we find amplitude 8 phase fluctuations in the transmitter, receiver, etc. due to temperature changes in the measurement environment over time, and phase changes due to the cables etc. through which the RF signal passes. I can do it. Therefore, by observing the one-line width and phase of this signal, it is possible to investigate fluctuations in the near-field electric field measurement system over time.

Therefore, using the signal distributed at the feeding point of the antenna under test at a certain time (for example, at the start of measurement) as a reference, A and △φ are applied to the amount of change in the amplitude and phase of the system over time after μ. Transmitter 20 and antenna under test 23
By correcting the probe reception signal using the variable phase shifter 22 and variable attenuator 21 inserted between the two, it is possible to eliminate fluctuations in one phase of the amplitude of the system system and always maintain the base value at the same level. .

Using the above, consider the case where the near electric field value of the antenna to be measured is measured using the probe scanning method shown in FIG. 2 using the measured method.

The output signal distributed at the feeding point of the probe is connected to the receiver 31, and the probe output signal is terminated without reflection. This receiver 31
The amplitude A1 phase φ of the signal distributed at the feeding point of the antenna to be measured detected in is used as a reference, the value is recorded in the CPU 32, and this value is used for continuous running from now on. At this time, the switching device 3o switches and receives the probe output signal and the output signal distributed at the feeding point of the antenna under test at an interval much shorter than the time the probe travels between the measurement point and the next measurement point. Connect to machine 31.

The CPU 32 calculates the amount of change ΔA, Δφ from the previously determined reference signal (A, φ). Information on the change rates ΔA and Δφ is sent to the variable phase shifter 22 and the sterilization device 24 that controls the variable attenuator 21.

The control device 24 corrects the previous fluctuation amount by powering the variable phase shifter 22 and the variable attenuator 21 by amounts corresponding to the information ΔA and Δφ. When an electronic phase shift operation using a PIN diode or a variable capacitance diode is used as the variable phase shifter 22 and a diode-loaded attenuator is used as the variable attenuator 21, the bias voltage applied thereto.

By changing the current, A can be moved to phase shift △φ decrease attenuation.

On the other hand, the CPU 32 performs an averaging operation based on the output signal of the probe 27 in order to adjust the phase of the signal at the measurement point.

The probe position detection device 29 detects the position of the probe, and when the position of the probe is aligned with the measurement point, the microwave switch of the switching device 3o receives the output signal of the break 27. 31, and the output signal distributed at the feeding point of the antenna to be measured is terminated without reflection.

The signal detected at this time is stored in the data storage device 33.

In the data obtained by two-dimensional scanning, even amplitude two-phase fluctuations in the transmitter/receiver system due to the influence of the temperature of the measurement environment during one cruise scan are corrected.

Furthermore, even when measuring by dividing the near electric field scanning plane, the amplitude of the transmitter/receiver system between each divided area 1
Phase errors can also be corrected during measurement.

Therefore, if this data is used to determine the far-field radiation directivity of the antenna under test, a more accurate directivity than that determined by the conventional method can be obtained.

The present invention is effective for high-sensitivity measurement.

Furthermore, the work of collecting calibration data after all measurements, which is done in the conventional method, becomes unnecessary.

The same 4'H effect can be obtained by inserting the variable attenuator and variable phase shifter described above on the reference signal side, that is, between the transmitter and the mixer 25a.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a conventional near electric field measuring device, FIG. 2 is a diagram for explaining a conventional correction method, and FIG. 3 is a diagram showing an embodiment of the present invention. 20... Transmitter, 21... Calibration variable phase shifter, 22.
... Calibration variable phase shifter, 23 ... Antenna under test, 24
...Control device, 25...Mixer, 26...Scanning frame, 27...Probe, 28...Drive device, 29...
...1fl detection device, 30...switching device, 31...
- Receiver, 32... cPU, 33... data storage device. Representative patent attorney Nori Chika 1st right (and 1 other person) 1st
Figure 2 Figure 3

Claims (1)

[Claims] An antenna to be measured, a transmitter IIF transmitting f@ to the antenna to be measured, a probe that measures a near field value of the antenna to be measured, and a receiver 1 that receives a 1F signal from the probe; In a plane scanning near-field electric field measuring device comprising a device for driving the probe, a device for detecting the position of the probe, and a device for storing amplitude and phase information from the receiver, there is a device between the transmitter and the antenna to be measured. With a variable attenuator and a variable phase shifter provided, ′, #! i,
means for distributing the transmission signal supplied to the measurement antenna to a mixer; a device for switching between the output signal of the mixer and one word after passing the signal received by the probe through the mixer; and the switching device. a device for detecting a change over time in a signal distributed at the feeding point of the antenna under test obtained through the above, and a control for correcting the detected change amount with respect to the variable attenuator and variable phase shifter. 1. A near-field electric field measuring device, characterized in that the device comprises: 11+N.