RU2244937C1 - Two-probe method of measuring phase shifts in balance ring - Google Patents

Abstract

FIELD: measurement technology.

SUBSTANCE: method can be used for aerial and wave-guide engineering as for measuring parameters as of single components and of group components. Method of measuring is based on separating of continuous signal to two arms. Two-probe phase-sensitive element and device which parameters have to measured are mounted in one arm and phase modulator is mounted into the other arm. Phase modulator has two states - of 0 and 180 degrees. During process of measurement two microwave frequency signals are added at both probes. One of signals carries information of phase of device to be measured and the other one has to be reference one. Phase shift introduced by device to be measured is determined by calculation by using signal amplitudes at two motionless probes for two beats - for first beat at initial phase state of microwave signal and for second beat when phase state is changed for 180 degrees in one arm of balance ring.

EFFECT: simplified realization; improved precision of measurement.

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Description

The proposed method for measuring phase shifts of microwave signals in a balanced ring relates to the field of radio engineering measurements and, in particular, for measurements in the microwave range.

A known method of measuring phase shifts using a phase Converter containing a strip measuring line with two probes placed on a movable carriage. The signals from the probes are detected, amplified and fed to a control circuit that automatically moves the carriage of the probe device along the line when tracking changes in phase shifts. [Sobolev D.P., Mansheva G.G. Information and reference leaflet, No. 780625, M., VIMI, 1978]

Closest to the technical nature of the present invention is a method for measuring phase shifts, based on the use of microwave bridge balanced circuit using a measuring line with two probes. The reference and studied signals are fed through the matched attenuators to the measuring line, and the signals from the probes after detection are fed to a two-channel recording device. The desired phase shift is found by the equality of the signals from the probes during mechanical movement of the carriage, while the minimum signal must be between the probes. [Sobolev D.P., Mansheva G.G. Methods for measuring the phase parameters of microwave devices. Reviews on electronic technology, 1980].

The disadvantage of these methods is the low speed of phase shift measurements.

The technical result of the proposed method for measuring phase shifts is the ability to significantly increase the speed of measurements of phase shifts with high accuracy.

The essence of the proposed method for measuring the phase shifts of microwave signals in a balanced ring consists in dividing a continuous microwave signal into two arms, one of which has a measured device and a two-probe phase-sensing element, summing on each of the mentioned probes two microwave signals, one of which carries information on the phase of the measured device, and the other is the reference, comparing these signals and determining the phase shift. The novelty of the proposed two-probe method for measuring phase shifts in a balanced ring is that the phase shift is measured in two steps with the measurement of the amplitudes of the signals on two stationary probes at the initial phase state of the microwave signal for the first cycle and when the balance ring is changed in one of the arms to 180 ° phase state of the microwave signal in the second cycle, determining the amplitude of the signals on both probes, followed by calculating the phase shift introduced by the measured device, in accordance with the expression:

where U ₁₁ and U ₁₂ are the amplitudes of the signals from the first probe in the first and second measures of the measurement cycle;

U ₂₁ and U ₂₂ are the amplitudes of the signals from the second probe in the first and second measures of the measurement cycle;

Δ = 0 if (U ₂₁ · U ₁₂ -U ₁₁ · U ₂₂ )> 0 and (U ₂₁ · U ₁₁ -U ₁₂ · U ₂₂ > 0

or (U ₂₁ · U ₁₂ -U ₁₁ · U ₂₂ ) <0 and (U ₂₁ · U ₁₁ -U ₁₂ · U ₂₂ > 0

Δ = 180 ° if (U ₂₁ · U ₁₂ -U ₁₁ · U ₂₂ )> 0 and (U ₂₁ · U ₁₁ -U ₁₂ · U ₂₂ ) <0

or (U ₂₁ · U ₁₂ -U ₁₁ · U ₂₂ ) <0 and (U ₂₁ · U ₁₁ -U ₁₂ · U ₂₂ ) <0

γ is the phase shift between the probes in the phase-sensitive element at the measurement frequency.

Figure 1 shows a functional diagram of a device that implements the proposed method for measuring phase shifts.

Figure 2 shows the voltage diagrams at the outputs of the probes for one measurement cycle.

A device that implements a method of measuring the phase shifts of microwave signals in a balanced ring, an example of which is shown in Fig. 1, consists of a generator 1, 3-decibel balanced divider 2, a phase modulator 3, a measured device 4, the first valve 5, the second valve 6 , a dual-probe phase-sensing element 7, a first detector section 8, a second detector section 9, a first analog-to-digital converter 10, a second analog-to-digital converter 11, an interface device 12, a personal computer 13.

The principle of operation of the device that implements the proposed measurement method is as follows: the continuous microwave signal from the generator 1 is divided into two arms with equal amplitudes in a 3-decibel balance divider 2. Next, the signal from one of the arms of a 3-decibel balance divider 2 is fed to the phase modulator 3 and through the measured device 4 and the second valve 6 to the first input of the dual-probe phase-sensing element. The signal from the second arm (reference signal) through the valve 5 enters the input 2 of the two-probe phase-sensing element 5. Next, the signals from the two-probe phase-sensing element are detected by the first and second detector sections 8 and 9, converted into digital form in the first and second analog-to-digital converters 10 and 11 and enter through the interface device 12 in the PC 13.

The cycle of one measurement consists of two clocks differing in the state of the phase modulator 3 (0 or π), in each of which, on a command from the PC 13, the amplitudes of the signals from the two probes of the two-probe phase-sensing element 7 are measured, followed by the calculation of the phase shift introduced by the measured device using the expression proposed for this method with the registration of the measurement results in a PC 13.

Technical and economic advantages of the proposed method compared to the prototype is to significantly reduce the time of an individual measurement, the possibility of using the proposed method for measuring phase shifts in the automation of measurements.

The possibilities of practical implementation of the proposed method are not in doubt. An experimental sample of the device that implements the proposed measurement method was manufactured and tested.

Claims (1)

A two-probe method for measuring the phase shifts of microwave signals in a balanced ring based on dividing a continuous microwave signal into two arms, one of which has a measuring device and a two-probe phase-sensing element, summing on each of the mentioned probes two microwave signals, one of which carries information about the phase of the signal on the measured device, and the other is the reference, comparing these signals and determining the phase shift, characterized in that the phase shift is measured using two probes in two cycles, in the first cycle with the initial phase state of the microwave signal, and in the second with the phase state of the microwave signal changed in one of the arms by 180 °, determining the amplitude of the signals on both probes, calculating the phase shift according to the expression

where U ₁₁ and U ₁₂ are the amplitudes of the signals from the first probe in the first and second measures of the measurement cycle; U ₂₁ and U ₂₂ are the amplitudes of the signals from the second probe in the first and second measures of the measurement cycle; Δ = 0 if (U ₂₁ · U ₁₂ -U ₁₁ · U ₂₂ )> 0 and (U ₂₁ · U ₁₁ -U ₁₂ · U ₂₂₎ > 0 or (U ₂₁ · U ₁₂ - U ₁₁ · U ₂₂ ) <0 and (U ₂₁ · U ₁₁ -U ₁₂ · U ₂₂₎ >0; Δ = 180 ° if (U ₂₁ · U ₁₂ -U ₁₁ · U ₂₂ )> 0 and (U ₂₁ · U ₁₁ -U ₁₂ · U ₂₂ ) <0 or (U ₂₁ · U ₁₂ -U ₁₁ · U ₂₂ ) <0 and (U ₂₁ · U ₁₁ -U ₁₂ · U ₂₂ ) <0; γ is the phase shift between the probes in the phase-sensitive element at the measurement frequency.

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