RU1805407C - Device for measuring reflection factor of microwave two-terminal network - Google Patents

Abstract

The invention relates to a radio measurement technique and can be used to measure the modulus and phase of the complex reflection coefficient of microwave bipolar. The purpose of the invention is to increase accuracy and reduce measurement time. The device comprises a microwave signal generator, a multiphase sensor, a switch, a synchronous detector, an integrator, a synchronizer, an analog-to-digital converter, and a processing and control unit. An increase in accuracy is achieved by choosing the distance between the probe probes that is a multiple of the 2M part of the wavelength, where N is the number of probes, and the reduction in measurement time is due to the introduction of a synchronous detector, integrator and synchronizer. 1 ill.

Description

The invention relates to microwave measurement technology and can be used to measure the complex reflection coefficient in microwave paths, and can also be used in the electronics industry to automate the process of measuring the module and phase of the reflection coefficient of a microwave load.

The purpose of the invention is to improve measurement accuracy and reduce measurement time.

The proposed device for measuring the module and phase of the reflection coefficient in microwave paths differs from the prototype in the following design features:

1. The optimal arrangement of sensors, in which the distances between adjacent sensors are directly proportional to the wavelength in the microwave path and inversely proportional to the number of sensors.

2, the introduction of the transducer meter ..

In the measuring line of the device used for measuring the impedances and standing wave coefficient over a wide frequency range, there is a feature similar to the first feature of the claimed device: a part of the sensors of the measuring line are located at arbitrary equal distances from each other. The expansion of the dynamic and frequency range is achieved by installing two additional sensors in the planes of connecting the measuring line to the microwave generator and to the load under study. However, this measuring line does not allow measurements to be made with the highest possible accuracy in the sense of minimizing the mean square error at any frequency out of working range. By00

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improved accuracy is achieved only in the modest range. Placing all the sensors at the indicated distances in the measuring line of the claimed device allows measurements to be made with the smallest possible mean-square error at a given frequency.

A device is known having a feature similar to the second feature distinguishing the claimed device from the prototype. The device comprises an analog multiplier and an integrator connected in series and is used to estimate the amplitude of a signal of a known shape. In the claimed device, the measuring transducer consists of a series-connected synchronous detector, an integrator and an ADC controlled by a synchronizer, the synchronizer simultaneously performing amplitude modulation of the generator. As an analog multiplier, a synchronous detector is used here. The use in the inventive device of a measuring transducer consists of a series-connected synchronous detector, an integrator and an ADC controlled by a synchronizer, the synchronizer simultaneously performing amplitude modulation of the generator. As an analog multiplier, a synchronous detector is used here. The use of a measuring transducer in the inventive device simultaneously with the estimation of the signal amplitude allows eliminating transients during sequential interrogation of sensors, which reduces the measurement time.

An analysis of the properties of the claimed and known solutions shows that the claimed device has a new property that does not coincide with the properties of the known solutions - the ability to take measurements with the greatest possible accuracy at a given frequency and at the same time reduce the measurement time of the module and

microwave reflectance phase.

The drawing shows a block diagram

The claimed device.

The device. Contains a microwave signal generator 1 connected to the measuring path 2, along which the measuring sensors 3 are located. A load 4 is connected to the output of the measuring path 2, the outputs of the measuring sensors 3 are connected to the measuring transducer 6 through the switch 5 6. Measuring transducer 6 consists of a synchronous detector 7, an integrator b / synchronizer 9 and an analog-to-digital converter (ADC) 10, and the synchronous detector 7,

the integrator 8 and the ADC 10 are connected in series, and the outputs of the synchronizer 9 are connected to the control inputs of each of them. The measuring transducer 6 is also connected to the control unit 11, the switch 12 and the microwave signal generator 1. The control unit 11 is connected to the switch 5, and ADC 10 with calculator 12.

The device operates as follows.

A microwave wave generator 1 and a load 4 generate a stagnation wave in the measuring path 2. The synchronizer 9 implements an amplitude one. modulation of the generator 1. Signals from the outputs of the sensors, proportional to the squares of the voltages of the standing wave at their locations, are fed through a switch controlled by the control unit 11

5 to a transducer 6, where it is converted using a synchronous detector 7, an integrator 8, a synchronizer 9, and an ADC 10 as follows. After the start of the conversion command received from the control unit 11 during the time Ti, the integrator 8 is reset, then during the time Ta the signal is integrated from the output of the synchronous detector 7, after which the output of the synchronous

the detector is disconnected from the input of the integrator, and the signal from the output of the integrator is digitized using the ADC 10. The measurement result and notification of the end are transmitted to the calculator 12

transformations. The calculator processes the measurement information using the formulas. The synchronizer 9 generates a signal of amplitude modulation of the microwave generator, the reference voltage of the synchronous

detector and integrator control signals.

The layout of the installation is based on the Electronics-60 microcomputer, used as a control unit 11 and a computer 12. As a generator 1, a microwave generator G4-79 is used.

The measuring path 2 is based on a 45 x 90 waveguide with a coaxial-wave transition for connecting

with a generator 1 and a flange for connecting the load 4. Eight sensors 3 () are placed along the wide wall of the waveguide at a distance of 54.5 mm from each other (which corresponds to, 53 cm) and contain

communication element - a pin, an attenuator and a detector diode M33402-7 immersed in the waveguide. Switch 5 and measuring transducer 6 are mounted on the integrated I5 interface board integrated into the Microelectronics-60 microcomputer.

Switch 5 and synchronous detector 7 are made on analog keys of K590 series microchips, integrator 8 uses K140 series operational amplifier and analog keys of K590 series, ADC is made on K572 microchip, synchronizer 9 consists of a clock generator and timers made on K155 series microchips. Communication between the switch 5 and the measuring transducer 6 with the interface The common bus of the microcomputer is carried out through the unified interface I5 Electronics-60.

The device allows you to:

1. Ensure the required measurement accuracy of the module and phase of the reflection coefficient of the microwave load at a given frequency by selecting the required number N of optimally located sensors. In this case, due to the selection of the parameter of the location of the sensors K, it is possible to make a convenient arrangement of sensors for technical implementation. The used arrangement of the sensors minimizes the determinate of the matrix (Z-Z) (Z-Z) T of errors of measurement of the amplitude of the standing wave, module and phase of the reflection coefficient of the load, which for the proposed device has the form:

the error matrices R of the claimed device with the corresponding error matrices of the analogue and prototype gives an increase in the accuracy of measurements of the module and phase of the reflection coefficient 5 in microwave paths by N / 3 times relative to the analogue and by 10-12% compared with the prototype.

2. Increase the measurement speed by 4.5-8 times in comparison with the prototype, depending on the required accuracy of measuring the voltage of the sensors. The reduction of the measurement time is achieved by eliminating the transients that occur in the converters used in the analogue and prototype. For the same variances of errors, the measured voltage of the sensors, the time constant T should be equal to the integration time. T2 integrator, while the transition process Tn

0 is e, where Ј is the relative measurement accuracy. For an inventive device comprising a transducer, the measurement time of the sensor signal is: T T1H-T2 + Tdzh, where Tdzh 5 is the time of the analog-to-digital converter. Typically, Ti > T > T2, with an increase in sensor interrogation rate of e times. For example, with a 7-bit ADC E and, 5 with

0 12-bit ADC e 3 x,. When the signal-to-noise ratio in the processing unit is less than 10-14 dB in the prototype, the use of a measuring transducer makes it possible to obtain unbiased estimates of the amplitudes

5 signals from sensors, which improves the accuracy of measurement of the module and phase of the reflection coefficient.

, / - g

Z (p, G, (p) is the vector of calculated parameter values; Z (p, G, p) t is the vector of their true values; P is the square of the voltage amplitude of the sensors; G, -tp is the module and phase of the reflection coefficient of the load; N is the number of sensors; c is the dispersion of errors in measuring the amplitudes of the sensor signals; E.,. Is the operator of mathematical expectation. The location that minimizes the determinate of the error matrix proportional to the square of the ellipsoid of measurement errors is D - the optimal experimental design in the least squares method and provides measurement error independence module and phase, which is an important advantage of the proposed arrangement of sensors compared to analog. and prototype.

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Claims (1)

The claims  A device for measuring the reflection coefficient of a two-port microwave, comprising serially connected microwave signal generator and multi-probe a sensor, the output of which is an output for connecting the studied two-pole receiver, and the outputs of the probes are connected to the inputs of the switch, the analog-to-digital converter and the processing and control unit are connected in series, the first control output of which is connected to the control input of the switch, from moreover, that, in order to improve accuracy and reduce measurement time, the output of the switch is connected to the input of the analog-to-digital converter through the synchronous detector and integrator introduced in series, the reference inputs of the synchronous detector. the integrator and the analog-to-digital converter are connected respectively to the first, second, and third outputs of the introduced synchronizer, the fourth output of which is connected to the control input of the microwave signal generator, and the input is connected to the second additional output of the processing unit and control, while the UL distance between the probes of the multi-probe sensor is selected from the ratio K / 2N, where N is the number of probes, A is the wavelength in the multi-probe sensor, K is an integer multiple of N / 2.