SU1285399A1 - Device for measuring phase characteristics - Google Patents

Abstract

The invention relates to radio engineering and provides an increase in the measurement accuracy of phase x-k for microwave elements having a coefficient. transfer close to one. The device contains a microwave generator 1, power dividers 2.15, ferrite valves 3.5, investigated microwave element (IE) 4, coherent light source 6, optical phase shifters (OF) 7,13, beam splitter 8, phase detectors (PD ) 9.14, adders 16.18, gauge ratio 17, phase 19 indicator, reference voltage source 20. PD consists of an avalanche photodiode 10, a matching circuit 11 and a low-pass filter 12. Ferrite valve 3, IE 4 and the power divider 15 form a measuring channel. The signal passing through it changes its phase and amplitude in accordance with the phase and modulus of the coefficient. transmission of IE 4. Ferrite valve 5, coherent light source 6, OF 7 and beam splitter 8 form a supporting channel. The PF 7 is used for calibration, and the PF 13 is used to shift the signal phase by 90. PD 9, 14 infuse the cosine and sine components, respectively, of the phase difference of the oscillations of the reference and measurement channel. Adders 16,18 are used to compensate for the signals acc. The PD component determined by the working point of the avalanche photodiode 10. The signal generated by the ratio meter 17 is proportional to the tangent of the oscillation phases in the reference and measurement channels. 1 il. a sl tsD 00 cl co; 0

Description

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11285399

The invention relates to a measurement technique and can be used to measure the phase characteristics of radio devices at high and ultrahigh frequencies.

The purpose of the invention is to improve the accuracy of measuring phase characteristics for microwave elements having a transmission coefficient close to one.

The drawing shows a block diagram of a device for measuring phase characteristics.

The device for measuring phase characteristics contains a microwave generator 1, the output of which is connected to the input of the first power divider 2, to the first input of which is connected the input of the first ferrite valve 3, the output of which is the input for connecting the investigated CB 1-element. 4, the second output of the first power divider 2 is connected to the input of a second. Ferrite valve 5, the output of which is connected to the modulating input of the source 6 of coherent light, the output of which is optically coupled to the input of the first optical phase shifter 7, the output of which is optically coupled to the beam splitter 8 input, the first beam splitter 8 output is optically coupled to the optical input of the first phase detector 9 consisting of an avalanche photodiode 10 with a matching circuit 11 at the radio frequency input and a low pass filter 12 at the output, the second output the beam splitter 8 is optically coupled through the second optical phase shifter 13 to the optical input of the second phase detector 14, identical to the first, second power divider 15, the input of which is the input for connecting the microwave element 4 being investigated, and the first output of the power divider 15 is connected to radio clock inputs first 18 and second 16 adders. The first ferrite, the gate 3, the microwave element 4 under study and the second power divider 15 form the measuring channel.

The second ferrite valve 5, the coherent light source 6, the first optical phase shifter 7 and the beam splitter 8 form the reference channel. , A bias-modulated semiconductor laser can be used as a source of coherent light with a modulating input.

Identical ferrite gates 3 and 5 serve to isolate and reduce the influence of reflected waves in the measuring and reference channels, matching circuits 11 serve to match the complex impedances of avalanche photodiodes 0 with the channel of measuring oscillations. The first optical phase shifter 7 serves for calibration, the second optical phase shifter 13 serves to shift the phase of the signal that modulated the light beam in the reference oscillation channel by 90. The first and second optical phase shifters 7 and 13 can be a mechanically coupled system of four mirrors, with the help of which a change is made in the geometric length of the reference channel for the transmitted light beam, the modulated reference. vibrations, and are standard 35 optical elements.

The beam splitter 8 serves to divide the modulated reference oscillations of the light beam into two beams of equal intensity and can be made in the form of an inclined semi-transparent mirror

Identical 12 low-pass filters are used for selection in la currents. wine photodiodes 10 phase difference

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the first input of the phase detector between the reference oscillator 9, the second output with radio frequencies modulated by the intensity input of the second phase detectability of the light beam generated 14, the output of which is connected to the source 6 of coherent light, and the output input of the second adder 16, by the oscillations of the measuring channel, the stroke of which is connected to the second input 50 passing the microwave element 4 under study

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rymi inputs of the first 18 and second 16 adders. The first ferrite, the gate 3, the microwave element 4 under study and the second power divider 15 form the measuring channel.

The second ferrite valve 5, the coherent light source 6, the first optical phase shifter 7 and the beam splitter 8 form the reference channel. , A bias-modulated semiconductor laser can be used as a source of coherent light with a modulating input.

Identical ferrite gates 3 and 5 serve to isolate and reduce the influence of reflected waves in the measuring and reference channels, matching circuits 11 serve to match the complex impedances of avalanche photodiodes 0 with the channel of measuring oscillations. The first optical phase shifter 7 serves for calibration, the second optical phase shifter 13 serves to shift the phase of the signal that modulated the light beam in the reference oscillation channel by 90. The first and second optical phase shifters 7 and 13 can be a mechanically coupled system of four mirrors, with the help of which a change is made in the geometric length of the reference channel for the transmitted light beam, the modulated reference. vibrations, and are standard 35 optical elements.

The beam splitter 8 serves to divide the modulated reference oscillations of the light beam into two beams of equal intensity and can be made in the form of an inclined semi-transparent mirror

Identical 12 low-pass filters are used for selection in la currents. wine photodiodes 10 phase difference

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 the component between the reference oscillations, which are modulated in intensity by the light beam generated by the coherent light source 6, and the oscillations of the measuring channel, 50 passed through the microwave element 4

the ratio meter 17, the output of the first phase detector 9 is connected to the first input of the first adder 18, the output of which is connected to the first input of the ratio meter 17, the output of which is connected to the phase indicator 19, the reference voltage source 20, the output of which is connected to the second input to avalanche photodiodes 10 with matching chains 11.

The first and second adders 18 and 16 serve to compensate for the output 55 signals of the first and second phase detectors 9 and 14 of the constant component determined by the position of the operating point of the avalanche photodiode 10.

Compensating voltages are supplied from the source 20 of the reference voltage.

The ratio meter 17 serves to divide the output signals of the first and second adders 18 and 16.

The phase indicator 19 serves to indicate a phase-ratio signal.

A device for measuring phase characteristics works as follows.

The microwave signal from the SBS generator 1 is fed to the input of the first power divider 2, the outputs of which receive two common-mode signals. One of these signals enters the measuring channel and, having passed through the first ferrite valve 3 and the microwave element 4 under study, will change its phase and amplitude in accordance with the phase and gain modulus of the microwave element 4 being studied. to the input of the second power divider 15, the outputs of which receive two common-mode signals of the same level, one of which goes through the matching circuit 1 to the input of the avalanche photodiode 10 of the first phase detector 9, and the second through the matching circuit 11 to the input of the avalanche photodiode 10 of the second phase detector 14.

The signal from the second output of the first divider 2. The power enters the channel reference oscillations. Passing through the second ferrite valve 5, this signal goes to the modulating coherent light source 6 and modulates the intensity of the microwave reference oscillations generated by this light source.

The intensity modulated light beam from the coherent light source 6 passes through the first optical phase shifter 7 and enters the beam splitter 8. Two light beams of equal intensity are output from the splitter 8 beam. The first of these beams is fed to the optical input of the first phase detector 9. The second light beam from the splitter 8 beam enters the second optical phase shifter 13 and further to the optical input of the second phase detector 14. The path lengths of the optical beams from the splitter 8 beam to the avalanche photodiode 10 of the first phase the detector 9 and from the splitter 8 beam through the second optical phase shifter 13

before the avalanche photodiode 10 of the second phase detector 14 is distinguished by a quarter of the wavelength of the microwave signal from the microwave generator 1, which is intensity-modulated by the light beam.

The currents of the avalanche photodiodes 10 of the first and second phase detectors 9 and 14 are determined by both the high-frequency voltage applied to them, coming from the matching circuits 11 of the first and second phase detectors 9 and 14 from the measuring channel, and the intensity of the optical radiation coming to them from the splitter 8 beams and from the second optical phase shifter 13. The intensity of the light beams varies in time with the reference microwave signal coming to the coherent light source 6 from the second ferrite valve 5.

The currents of the avalanche photodiodes 10 of the first and second phase detectors 9 and 14 will contain constant components determined by the operating points of the avalanche photodiodes 10, and phase difference components. Since the optical channel spacings for light radiation entering the avalanche photodiodes 10 of the first and second phase detectors 9 and 14 differ by a quarter of the modulating wave of the microwave signal, the optical modulation signal components of the photodiodes IO will be out of phase by 90. As a result, the phase difference component of the current of the avalanche photodiode IO of the first phase detector 9 will be proportional to the cosine of the phase difference between the oscillations of the reference and measuring channels, and the phase difference component The current of the avalanche photodiode 10 of the second phase detector 14 will be proportional to the sine of the phase difference between the oscillations of the reference and measurement channels.

Since the first and second phase detectors 9 and 14 are identical, the signals arriving at their RF inputs are the same, and the signals arriving at their optical inputs differ only in the phase of the modulation signal, the constant components of the currents of the avalanche photodiodes 10 and The second phase detectors 9 and 14, determined by the operating point of avalanche photodiodes 10, will be the same, and the phase difference components of the current

Wine photodiodes 10 of the first and second phase detectors 9 and 14 will differ in phase: the cosine and sine of the phase difference of the oscillations in the reference and measurement channels. These components of avalanche photodiodes 10 of the first and second phase detectors 9 and 14 are separated by identical low-pass filters 12 of the first and second phase detectors 9 and 14 and are supplied respectively to the first adder 18 and the second adder 16. In the first and second the adders 18 and 16 from the output signals of the first and second phase detectors 9 and 14 subtract the voltage equal to the component of the output signals of the first and second phase detectors 9 and 14, determined by the operating point of the avalanche photodiodes 10. This voltage enters source of reference voltage 20, its level is set during calibration, when analyzed microwave element 4 is removed from the tract. The signal from the output of the first adder 18 will be equal to the product of the amplitude of the phase difference component of the output signal of the first phase detector 9 and the cosine of the phase difference of oscillations in the reference and measurement channels. The output signal from the second adder 16 will be equal to the product of the amplitude of the phase difference component of the output signal of the second phase detector 14 and the sine of the phase difference of the oscillations in the reference and measurement channels. Both output signals of the first and second adders 18 and 16 are fed to the first and second inputs of the ratio meter 17, where they are divided into each other. Since the amplitudes of the phase difference components of the first and second phase detectors 9 and 14 are equal, after dividing the output signal of the ratio meter 17 will be proportional to the tangent of the phase difference of the oscillations in the reference and measurement channels and will not depend on the voltage level in the measurement channel and the intensity of light in the reference i.e. from the module of the transmission coefficient of the investigated microwave element 4.

A signal proportional to the tangent of the difference of the phases in the reference and measuring channels is indicated on the indicator 19 phase.

Initial calibration and voltage setting from reference source 20

the voltages can be carried out using the first optical phase shifter 7 in the calibration mode, when the microwave element 4 under study is excluded from the measuring path. For calibration, you can also use the switching of the inputs of the ratio meter 17.

Using the second optical phase rotation 13, the zero point of the phase meter can be shifted, which makes it possible to regulate the slope of the measurement characteristic over a wide range.

Formula of the invention

A device for measuring phase characteristics, comprising a microwave generator, the output of which is connected to the input of the first power divider, the first output of which is connected to the input of the first ferrite valve, the output of which is the input for connecting the microwave element under study, is connected to the second output of the first power divider a ferrite valve, the output of which is connected to the modulating input of a coherent light source, the output of which is optically connected to the input of the first optical phase shifter,

phase detector with optical and radio frequency inputs, consisting of an avalanche photodiode, with a matching circuit at the radio frequency input and a low pass filter at the output, and a phase indicator, which is designed to increase the accuracy of the phase characteristics measurement for microwave elements having a coefficient transfer close to one entered

The second power divider, the first output of which is connected to the RF input of the first phase detector, and the second output to the RF input of the inputted second phase detector, identical to the first, the output of the first optical phase shifter is optically connected to the input of the inserted beam splitter, the first output of which is optically connected the optical input of the first phase detector, and the second output through the input of the second optical phase shifter - with the optical input of the second phase detector, the output of which is connected to

the first input of the input of the first adder, the output of which is connected to the first input of the entered ratio meter, the output of the second phase detector is connected to the first input of 71285399 8

The second adder, the output of which is connected to the secondary inputs of the torus, is connected to the second input of the first and second adders, the input of the ratio, the output of which the second power splitter is dinene with the phase indicator, is inputted to connect the test reference point voltage, output of the microwave element 5.

Claims (1)

Claim A device for measuring phase characteristics, containing a microwave generator, the output of which is connected to the input of the first power divider, the first output of which is connected to the input of the first ferrite valve, the output of which is the input for connecting the studied microwave element, the second ferrite input is connected to the second output of the first power divider a valve whose output is connected to a modulating input of a coherent light source, the output of which is optically coupled to the input of the first optical phase shifter, the first phase a detector with optical and radio-frequency inputs, consisting of an avalanche photodiode, with a matching circuit at the radio-frequency input and a low-pass filter at the output, and a phase indicator, characterized in that, in order to increase the accuracy of measuring phase characteristics for microwave elements having a transmission coefficient, close to unity, a second power divider is introduced, the first output of which is connected to the radio frequency input of the first phase detector, and the second output is connected to the radio frequency input of the inserted second phase detector, identical to To this, the output of the first optical phase shifter is optically connected to the input of the introduced beam splitter, the first output of which is optically connected to the optical input of the first phase detector, and the second output through the introduced second optical phase shifter with the optical input of the second phase detector, the output of which is connected to the first input of the input first adder , the output of which is connected to the first input of the entered relationship meter, the output of the second phase detector is connected to the first input of the input of the second adder 1285399, turn is connected to the second input meter relationship, the output of which is connected to the phase indicator, includes a source of reference voltage output to torogo coupled to second inputs of the first and second adders, the second input of the power divider is an input for connecting the test microwave element.