RU2524049C1 - Device for measuring absolute complex transmission and reflection coefficients of microwave devices with frequency conversion - Google Patents

Abstract

FIELD: radio engineering, communication.

SUBSTANCE: device for measuring absolute complex transmission and reflection coefficients of microwave devices with frequency conversion comprises a test microwave four-terminal device, a device for measuring parameters of microwave four-terminal devices which consists of a microwave test signal generator, a first switch and a matched load connected to said switch, a microwave heterodyne, first, second, third and fourth directional couplers, a vector voltmeter with an output contact, first and second ports, a test microwave mixer, a reference microwave mixer and a microwave generator. The device further includes a phase-locked-loop frequency control mixer, first and second intermediate frequency mixers, second, third and fourth switches, a reference frequency generator, a comparator and a computer, which, along with the test microwave mixer, the reference microwave mixer and the microwave generator, form a double-channel superheterodyne receiver. Connections of the new elements with each other and elements common with the prototype together form a device which enables to determine absolute complex transmission and reflection coefficients of a test microwave mixer without switching and reconnections in microwave circuits.

EFFECT: high measurement accuracy.

2 cl, 1 dwg

Description

The invention relates to the field of radio measurements and can be used to measure the absolute complex transmission and reflection coefficients of microwave devices with frequency conversion (microwave mixers).

Known devices for measuring complex (module and phase) transmission and reflection coefficients of microwave quadrupole, in the foreign literature referred to as vector network analyzers, which in the future will be called the parameters of the microwave quadrupole. (Abubakirov B.A., Gudkov K.G., Nechaev E.V. Measurement of parameters of radio engineering circuits. M: Radio and communication, 1984, p.118, Fig. 3.49). The microwave four-terminal parameter meter consists of a generator of test microwave signals, a microwave local oscillator coherent with it, two reflectometers, each of which contains a pair of directional couplers connected in the opposite direction. As well as a vector voltmeter having four inputs, each of which receives signals from the secondary channels of the directional couplers, converted to an intermediate frequency formed as the difference between the frequency of the test microwave signal and the microwave local oscillator signal. The microwave four-terminal parameter meter consists of two separate microwave paths, each of which includes an OTDR, which allows you to measure all four complex parameters of the scattering matrix of the tested four-terminal.

By themselves, such devices do not allow measuring the complex parameters of microwave mixers, and are often part of a complex device for measuring such parameters. Of particular difficulty is the measurement of the true phase shift introduced by the microwave mixer into the intermediate frequency signal during the heterodyne conversion of its input microwave signal, since these signals lie in different frequency ranges and, therefore, it is impossible to measure their phase shift by conventional methods.

A device for determining the transmission coefficients of frequency converters using the inverse heterodyne frequency conversion. This device consists of a microwave quadrupole parameter meter, a test one, and two reference mixers. With it, the total transmission coefficient and phase shift of the test and the first reference microwave mixers, the test and second reference microwave mixers, the first and second reference microwave mixers are measured. Then solve a system of three equations and calculate the absolute transfer coefficient and phase shift of the tested microwave mixer (US Pat. RF No. 2029966, IPC G01R 27/28, US Pat. No. 5,937,006, IPC Н04В 3/46, US Pat. No. 6,064,694 IPC, HB04 3/46).

A device for measuring the amplitude-frequency and phase-frequency characteristics of a four-port microwave with frequency conversion, consisting of a measuring phase bridge, which includes the test and one reference mixer. This device allows you to determine the overall transmission coefficient and phase shift of the test and reference microwave mixers, connected first in series and then in parallel. Next, a system of two equations is solved and the absolute transfer coefficient and phase shift of the tested microwave mixer are calculated (AS USSR No. 1475347, IPC G01R 27/28, USSR AS No. 1538149, IPC G01R 27/28).

However, the devices described above require at least six connections and disconnections in the microwave paths during the measurement procedure, which introduces significant errors into the measurements due to the non-identical mechanical connections of the microwave paths. Especially strongly, these errors affect the measurement of phase shifts.

The closest in technical essence to the proposed device is described in US Pat. US No. 7,415,373 IPC G01R 23/00, FIG. 1, a device for measuring the parameters of frequency converters, consisting of a four-terminal parameter meter microwave, the test and reference microwave mixer and microwave generator. In this device, the test and reference microwave mixers, connected in series, are connected to the ports of the four-terminal microwave parameter meter and have a common local oscillator, the role of which is played by the microwave generator. Such a connection, provided that the parameters of the reference microwave mixer are known, makes it possible to measure the complex transmission and reflection coefficients of the tested microwave mixer without any switching in the microwave paths.

However, this device has limited capabilities, as Allows you to measure only the relative complex parameters of the tested microwave mixer. They cannot measure the true (absolute) complex transmission and reflection coefficients of the tested microwave mixer, including its absolute true phase shift.

The technical result is to increase the accuracy of measuring complex transmission and reflection coefficients of the microwave.

To achieve a technical result, a device is proposed for measuring the absolute complex transmission and reflection coefficients of microwave devices with frequency conversion, containing the tested microwave four-terminal device, a microwave four-terminal parameter meter, consisting of a test microwave signal generator, a first switch and associated matched load, microwave - heterodyne, first, second, third, fourth directional couplers, vector voltmeter with output contact, first and second ports, isp a removable microwave mixer, a microwave reference mixer, a microwave generator. An additional phase locked loop mixer, a phase detector, first and second intermediate frequency mixers, a second, third, fourth switch, a reference frequency generator, a comparator and a computer, which together with the tested microwave mixer, a microwave reference mixer and a microwave generator two-channel superheterodyne receiver. The output of the test microwave signal generator is connected to the movable contact of the first switch, the first fixed contact of which is connected to the input of the main channel of the first directional coupler, the output of which is connected to the input of the main channel of the third directional coupler, the output of which is connected to the first port, which is connected to the first input of the test Microwave mixer. The first input of the microwave reference mixer is connected to a second port connected to the output of the main channel of the fourth directional coupler, the input of which is connected to the output of the main channel of the second directional coupler, the input of which is connected to the second fixed contact of the first switch. Depending on the position of the movable contact of the first switch, a matched load is connected to its fixed contacts. The outputs of the secondary channels of the first, second, third and fourth directional couplers are connected to the first, second, third and fourth inputs of the vector voltmeter, respectively, the fifth input of which is connected to the microwave local oscillator, while the second inputs of the test and reference microwave mixers are simultaneously connected to the microwave output -generator. The output of the vector voltmeter is connected to the output contact. The output of the tested microwave mixer is connected to the movable contact of the second switch, the first fixed contact of which is connected to the first fixed contact of the fourth switch, the second fixed contact of which is connected to the first fixed contact of the third switch, the movable contact of which is connected to the output of the reference microwave mixer. The second input of the reference microwave mixer is connected to the second input of the tested microwave mixer, the output of the microwave generator and the second input of the phase locked loop, the first input of which is connected to the output of the test microwave signal generator. The output of the phase locked loop is connected to the first input of the phase detector and the first input of the first intermediate frequency mixer, the output of which is connected to the second input of the comparator, the first input of which is connected to the output of the second intermediate frequency mixer, the first input of which is connected to the movable contact of the fourth switch, and the second its input is connected to the second output of the reference frequency generator and the second input of the first intermediate frequency mixer. The first output of the reference frequency generator is connected to the second input of the phase detector, the output of which is connected to the input of the microwave generator, the second fixed contacts of the second and third switches are interconnected, the output of the comparator is connected to the second input of the computer, the first input of which is connected to the output contact of the vector voltmeter. Depending on the type of measurements being taken, it is possible to disconnect the two-channel superheterodyne receiver from the first and second ports, and to connect the test microwave four-terminal device instead.

The first and second connectors of all four directional couplers are inputs or outputs of their main channels, depending on the position of the movable contact of the first switch.

Distinctive features of the proposed device for measuring the absolute complex transmission and reflection coefficients of microwave devices with frequency conversion are introduced into it: phase-locked loop, phase detector, reference frequency generator, second, third and fourth switches, first and second intermediate frequency mixers, comparator and computer. The connections of the newly introduced elements with each other and with the elements common with the prototype together form a device that allows you to determine the absolute complex transfer and reflection coefficients of the tested microwave mixer without performing switching and reconnecting in the microwave paths, thereby increasing the accuracy of measurements.

In FIG. presents a block diagram of the proposed device for measuring the absolute complex transmission and reflection coefficients of microwave devices with frequency conversion.

A device for measuring the parameters of frequency converters consists of a four-terminal parameter meter of microwave 1 and a two-channel superheterodyne receiver 2. The four-terminal parameter meter of microwave 1 includes: a generator of test microwave signals 3, a first switch 4 and its associated load 5, microwave oscillator 6 , first directional coupler 7, second directional coupler 8, vector voltmeter 9, third directional coupler 10, fourth directional coupler 11, output terminal 12 vect the voltmeter 9, the first port 13, the second port 14. Between the four-terminal parameter meter 1 and the two-channel superheterodyne receiver 2 there is a test microwave four-terminal 15. The two-channel superheterodyne receiver 2 includes a test microwave mixer 16, a reference microwave mixer 17, a phase mixer self-tuning frequency 18, microwave generator 19, phase detector 20, first intermediate frequency mixer 21, second switch 22, third switch 23, fourth switch 24, second intermediate frequency mixer 25, reference frequency generator 26, computer 27, comparator 28.

The output of the test microwave signal generator 3 is connected to the movable contact of the first switch 4, the first fixed contact of which is connected to the input of one main channel of the first directional coupler 7, the output of which two is connected to the input of one main channel of the third directional coupler 10, the output of which is connected to the first port 13. The second fixed contact of the first switch 4 is connected to the input of one main channel of the directional coupler 8, the output of two of which is connected to the input of one main channel the fourth directional coupler 11, the two output of which is connected to the second port 14. The outputs of the three secondary channels of the first 7, second 8, third 10, fourth 11 directional couplers are connected, respectively, with the first, second, third and fourth inputs of the vector voltmeter 9, fifth 5 the input of which is connected to the output of the microwave local oscillator 6. The output of the vector voltmeter 9 is connected to the output terminal 12. The first port 13 of the two-channel superheterodyne receiver 2 is connected to the first input of the tested microwave mixer 16, the output of which is three inen with the movable contact of the second switch 22, the first fixed contact of which is connected to the first fixed contact of the fourth switch 24. The second fixed contact of the second switch 22 is connected to the second fixed contact of the third switch 23, the movable contact of which is connected to the output of the three reference microwave mixer 17, the first input which is connected to the second port 14. The second input of the reference microwave mixer 17 is connected to the second input of the tested microwave mixer 16, the output of the microwave generator 19 and the second input mixes spruce phase locked loop 18, the first input of which is connected to the output of the test microwave signal generator 3. The output of three phase locked loop 18 is connected to the first input of the phase detector 20 and the first input of the first intermediate frequency mixer 21, the three output of which is connected to the second input of the comparator 28, the first input of which is connected to the output of three second intermediate frequency mixer 25, the second input of which is connected to the second output of the reference frequency generator 26 and the second input of the first mixer the exact frequency 21. The first input of the intermediate frequency mixer 25 is connected to the movable contact of the fourth switch 24. The first output of the reference frequency generator 26 is connected to the second input of the phase detector 20, the output of which is connected to the input of the microwave generator 19. The output of the comparator 28 is connected to the second input of the computer 27, the first input of which is connected to the output of the vector voltmeter 9 through the output terminal 12.

The phase locked loop 18, the microwave generator 19, the phase detector 20, the reference frequency generator 26, interconnected as described above, form a phase locked loop.

A device for measuring the absolute complex transmission and reflection coefficients of microwave devices with frequency conversion is as follows.

Before starting measurements, calibrate the microwave parameter meter of the four-terminal 1 according to one of the existing methods, for example (Agilent Application Note 1287-3 "Applying Error Correction to Network Analyzer Measurements").

After calibration, measure the product of the transmission coefficients and the sum of the phase shifts of the test 16 and the reference 17 microwave mixers connected in series as follows. The test microwave signal with a frequency f ₁ from the generator of the test microwave signals 3 through the switch 4 in the first position of its movable contact, through the main channels of the directional couplers 7 and 10 and the first port 13 is fed to the first (signal) input of the tested mixer 16, to the second (heterodyne) input which receives a microwave signal with a frequency f ₂ from a microwave generator 19, which performs the function of a local oscillator. The signal of the differential first intermediate frequency f _IF1 = f ₁ -f ₂ formed as a result of a heterodyne frequency conversion in the tested microwave mixer 16 from its output three through switches 22 and 23 in the second position of their movable contacts, three output used as input, the reference Microwave mixer 17. In the reference microwave mixer 17, as a result of adding the signal of the first intermediate frequency f _{IF 1} with the signal from the microwave generator 19 with a frequency f ₂ supplied to the second input of the reference microwave mixer 17, receive a signal equal in frequency to the test NE The f-signal f ₁ , where f ₁ = f _IF1 + f ₂ = (f ₁ -f ₂ ) + f ₂ at the first input used as the output of the microwave mixer 17. This signal with a frequency of f _{1 is} fed through the second port 14 and the main channels of the directional couplers 11 and 8 to the second fixed contact of the switch 4, to which a matched load 5 is connected. Based on the fact that the tested microwave mixer 16 having a phase shift φ ₁₆ , and the reference microwave mixer 17 having a phase shift φ ₁₇ are connected in series, their phase shifts add up. As a result, a total phase shift Σφ = φ ₁₆ + φ _{17 is} obtained between the first 13 and second 14 ports of the four-terminal microwave parameter meter 1. The transmission coefficients of the tested microwave mixer 16, K ₁₆ and the reference microwave mixer 17, K _{17 are} similarly multiplied. As a result of this, a common transmission coefficient ΣK = K ₁₆ K ₁₇ (total conversion loss) is obtained. The magnitude of the total phase shift Σφ and the total conversion loss ΣK between the first 13 and second 14 ports are recorded by the difference in phase shifts and the ratio of the amplitudes of the signals coming from the secondary channels of the first directional coupler 7 and the fourth directional coupler 11 to the first and fourth vector voltmeter 9. Measurement results the total transfer coefficient ΣK and the total phase shift Σφ from the output of the vector voltmeter 9 are fed through contact 12 to the first input of the computer 27, where they are fixed (recorded in its memory).

The value of the first intermediate frequency f_IF1 during the measurements, they are kept constant by means of a phase locked loop. The value of the first variable intermediate frequency f_IF1 is set using the reference frequency generator 26 and can be selected any within the operating range of the reference frequency generator 26, which in turn is determined by the operating conditions. The reference frequency generator 26 simultaneously with the signal of the first variable intermediate frequency f_IF1 produces a signal of the second intermediate frequency f_IF2continuously shifted relative to the signal of the first intermediate frequency by the value of the third constant intermediate frequency f_FC3coherent with the signal of the first and second intermediate frequency and equal to f_FC3= f_IF1-f_IF2, the value of which is stabilized by a quartz resonator (not shown in Fig.), which is an integral part of the reference frequency generator 26. The phase-locked loop operates as follows. At the first input of the phase locked loop 18, part of the test microwave signal with a frequency f_one from the generator of the microwave test signals 3, and the second input of this mixer 18 receives a signal from the output of the microwave signal generator 19. The signal from the output of the three phase locked loop mixer 18, equal to the frequency difference f_one-f₂ the microwave test signal generator 3 and the microwave generator 19 are fed to the first input of the phase detector 20, the second input of which receives a signal from the first output of the reference frequency generator 26. An error signal from the output of the phase detector 20 is fed to the input of the microwave generator 19, as a result of which its frequency f₂ follows changes in frequency f_one test microwave signal generator test microwave signals 3 so that the difference between the frequencies f_one and f₂ accurate to phase equal to the selected first intermediate frequency f_IF1. Even when the oscillator of the test microwave signal 3 oscillates in the frequency range, the difference between its frequency and the frequency of the microwave generator 19 due to the phase-locked loop will remain constant and equal to the selected first intermediate frequency f_IF1.

Then determine the ratio of the transmission coefficients and the phase difference of the test 16 and the reference 17 microwave mixers. To do this, measurements are made by comparing the amplitude and phase of the test signal from the output of three second mixers of intermediate frequency 25, formed as a result of double frequency conversion of the test microwave signal first from the test 16, and then the reference 17 microwave mixers, with the reference signal of the third intermediate frequency f _IF3 in the comparator 28, with the subsequent calculation of the ratio of the transmission coefficients and the difference of the phase shifts of the test 16 and the reference 17 microwave mixers in the computer 27.

Double frequency conversion is used to convert the signal of the first variable intermediate frequency f _IF1 into a signal of the third constant intermediate frequency f _IF3 and to compare phase shifts and amplitude differences in order to reduce the measurement error at a constant, relatively low intermediate frequency. The reference signal of the third intermediate frequency f _{IF3 is} obtained from the test microwave signal from the output of the test microwave signal generator 3 by double converting its frequency, first to the first intermediate frequency f _IF1 in the phase locked loop mixer 18, and then to the third intermediate frequency f _IF3 in the first intermediate frequency mixer 21, the signal of which is fed to the second input of the comparator 28.

; отношение произведения амплитуды сигнала второго порта 14 U₁₄ и коэффициентов передачи опорного смесителя 17 K₁₇ и второго смесителя промежуточной частоты 25 K₂₅ к постоянному опорному уровню сигнала U_ПЧ3 третьей промежуточной частоты f_ПЧ3, $$\frac{U_{14}{K}_{17}{K}_{25}}{U_{ПЧ3}}$$

. Для сдвигов фаз в компараторе 28 получают значения разности между суммой сдвигов фаз испытуемого смесителя 16 φ₁₆ и второго смесителя промежуточной частоты φ₂₅ и фазой опорного сигнала третьей промежуточной частоты φ_ПЧ3, (φ₁₆+φ₁₅)-φ_ПЧ3. Аналогично получают значения разности между суммой сдвигов фаз опорного смесителя 17 φ₁₇ и второго смесителя промежуточной частоты φ₂₅ и фазой опорного сигнала третьей промежуточной частоты φ_ПЧ3, (φ₁₇+φ₂₅)-φ_ПЧ3. Полученные значения $$\frac{U_{13}{K}_{16}{K}_{25}}{U_{ПЧ3}}$$

, $$\frac{U_{14}{K}_{17}{K}_{25}}{U_{ПЧ3}}$$

, (φ₁₆+φ₂₅)-φ_ПЧ3, (φ₁₇+φ₂₅)-φ_ПЧ3 с выхода компаратора 28 поступают на второй вход компьютера 27 и фиксируются в его памяти. В компьютере 27 вычисляют отношение коэффициентов передачи испытуемого смесителя 16 и опорного смесителя 17 (учитывая, что U₁₃=U₁₄):The test signal of the first variable intermediate frequency f _{IF 1 is} fed first from the output of the three tested microwave mixer 16 to the first input of the second intermediate frequency mixer 25 in the first position of the movable contact of the third switch 22 and the first position of the movable contact of the fourth switch 24, when measuring the transmission coefficient and phase shift the tested microwave mixer 16. Then the test signal of the first variable intermediate frequency f _{IF 1} c output three reference microwave mixer 17 to the first input of the second mixer between the exact frequency 25, in the first position of the movable contact of the third switch 23 and the second position of the movable contact of the fourth switch 24, when measuring the transmission coefficient and phase shift of the reference microwave mixer 17. The movable contacts of the second 22 and third 23 switches are transferred to the first position. Considering that after calibrating the complex parameters meter of the microwave four-terminal 1, the levels of amplitudes and phase differences between its ports 13 and 14 are equal to each other, they assign port 13 the signal amplitude U ₁₃ , and port 14 the signal amplitude U ₁₄ and U ₁₃ = U ₁₄ . Designate the transmission coefficient module of the tested microwave mixer K ₁₆ , its true phase shift φ ₁₆ , the transmission coefficient module of the reference microwave mixer K ₁₇ , its true phase shift φ ₁₇ , the transmission coefficient module of the intermediate frequency mixer K ₂₅ , and its true phase shift φ ₂₅ . Then the amplitude of the signal from port 13, which came to the first input of the comparator 28 in the first position of the movable contact of the switch 24, will be U ₁₃ (K ₁₆ K ₂₅ ), and the phase shift is φ ₁₆ + φ ₂₅ . Similarly, the amplitude of the signal from port 14, which came to the first input of the comparator 28 in the second position of the movable contact of the switch 24, will be U ₁₄ (K ₁₇ K ₂₅ ), and the phase shift is φ ₁₇ + φ ₂₅ . The amplitude and phase of the comparator 28 compares the signals supplied separately from the first port 13 and separately from the second port 14 to the first input of the comparator 28, converted in the second mixer of the intermediate frequency 25 into the third intermediate frequency f _{IF 3} with a constant amplitude and phase reference signal a third intermediate frequency f _PCH3 supplied from the output of three of the first intermediate frequency mixer 21, a second input of the comparator 28. The result obtained in the comparator 28, the signal amplitude ratio of the product of the first port 13 and U _13, and s ENTOV transmission subject K mixer 16 and second mixer _16, intermediate frequency 25 K ₂₅ to a constant reference level signal U _PCH3 third intermediate frequency f _PCH3, $$\frac{U_{13}{K}_{16}{K}_{25}}{U_{PH3}}$$

; the ratio of the product of the amplitude of the signal of the second port 14 U ₁₄ and the transmission coefficients of the reference mixer 17 K ₁₇ and the second mixer of the intermediate frequency 25 K ₂₅ to the constant reference level of the signal U _{ПЧ3 of the} third intermediate frequency f _ПЧ3 , $$\frac{U_{\mathrm{fourteen}}{K}_{17}{K}_{25}}{U_{PH3}}$$

. For phase shifts in comparator 28, the difference between the sum of the phase shifts of the tested mixer 16 φ ₁₆ and the second intermediate frequency mixer φ ₂₅ and the phase of the reference signal of the third intermediate frequency φ _IF3 , (φ ₁₆ + φ ₁₅ ) -φ _{IF3 is obtained} . Similarly, the difference values between the sum of the phase shifts of the reference mixer 17 φ ₁₇ and the second intermediate frequency mixer φ ₂₅ and the phase of the reference signal of the third intermediate frequency φ _{IF 3} , (φ ₁₇ + φ ₂₅ ) -φ _{IF 3 are obtained} . Values obtained $$\frac{U_{13}{K}_{16}{K}_{25}}{U_{PH3}}$$

, $$\frac{U_{\mathrm{fourteen}}{K}_{17}{K}_{25}}{U_{PH3}}$$

, (φ ₁₆ + φ ₂₅ ) -φ _ПЧ3 , (φ ₁₇ + φ ₂₅ ) -φ _ПЧ3 from the output of the comparator 28 go to the second input of the computer 27 and are recorded in its memory. The computer 27 calculates the ratio of the transmission coefficients of the test mixer 16 and the reference mixer 17 (given that U ₁₃ = U ₁₄ ):

$$\frac{\frac{U_{13}{K}_{16}{K}_{25}}{U_{PH3}}}{\frac{U_{13}{K}_{17}{K}_{25}}{U_{PH3}}}=\frac{K_{16}}{K_{17}}=\Delta K$$

And the difference in phase shifts between the subject 16 and the reference 17 mixers:

$$\left(({\varphi }_{16}+{\varphi }_{25})-{\varphi }_{PH3}\right)-\left(({\varphi }_{17}+{\varphi }_{25})-{\varphi }_{PH3}\right)={\varphi }_{16}-{\varphi }_{17}=\Delta \varphi$$

The values of ΔK and Δφ are recorded in the memory of the computer 27.

After measuring the sum and difference of the transfer coefficients and phase shifts of the test 16 and the reference 17 microwave mixers, the absolute transmission coefficients and phase shifts of the test microwave mixer 16 are calculated. The calculations are as follows.

, полученное в результате параллельных измерений испытуемого 16 и опорного 17 СВЧ-смесителей. В компьютере 27 решается система уравнений:In the memory of computer 27 there is a previously measured product of transmission coefficients ΣK = K ₁₆ K ₁₇ as a result of the sequential switching on of test subject 16 and reference 17 microwave mixers. As well as the ratio of gear ratios $$\frac{K_{16}}{K_{17}}=\Delta K$$

obtained as a result of parallel measurements of test subject 16 and reference 17 microwave mixers. In computer 27, a system of equations is solved:

$$\{\begin{array}{l}{K}_{16}{K}_{17}={\displaystyle \sum K}\\ \frac{K_{16}}{K_{17}}=\Delta K\end{array}$$

Find the actual values of the modulus of the transmission coefficients of the test and reference mixers, respectively:

, $$K_{17}=\sqrt{\frac{\Sigma K}{\Delta K}}$$

. $$K_{16}=\sqrt{\Delta K\Sigma K}$$

, $$K_{17}=\sqrt{\frac{\Sigma K}{\Delta K}}$$

.

In the memory of computer 27 there is the value of the sum of their phase shifts φ ₁₆ + φ ₁₇ = Σφ obtained as a result of successive switching on of test 16 and reference 17 microwave mixers. And also the value of the difference in their phase shifts φ ₁₆ -φ ₁₇ = Δφ, obtained as a result of parallel measurements of the test 16 and the reference 17 microwave mixers. In computer 27, a system of equations is solved:

$$\{\begin{array}{l}{\varphi }_{16}+{\varphi }_{17}=\Sigma \varphi \\ {\varphi }_{16}-{\varphi }_{17}=\Delta \varphi \end{array}$$

The actual values of the phase shift of test 16 and reference 17 microwave mixers are found, respectively:

, $${\varphi }_{17}=\frac{\Sigma \varphi +\Delta \varphi }{2}$$

. $${\varphi }_{16}=\frac{\Sigma \varphi +\Delta \varphi }{2}$$

, $${\varphi }_{17}=\frac{\Sigma \varphi +\Delta \varphi }{2}$$

.

The obtained absolute values of the module and phase of the complex transfer coefficient of the tested microwave mixer 16 are displayed on the computer screen 27 for the selected frequency point of the operating range of the test microwave signal generator 3, at the first intermediate frequency f _IF1 selected with the help of the reference frequency generator 20 and in the form of amplitude frequency and phase-frequency characteristics of this microwave mixer in the panoramic mode of its tests, with automatic swing of the generator of the test microwave signals 3 in its operating frequency range.

To measure at the frequency point the complex reflection coefficient of the tested microwave mixer 16 in the real operating mode of its operation using a vector voltmeter 9 measure the ratio of the amplitudes and the phase difference of the signals at its first and third inputs. In order to eliminate the influence of spurious signals arising in the tested microwave mixer, the frequency conversion of the signals supplied to the inputs of the vector voltmeter 9 using a microwave local oscillator 6 is used.

In addition, the microwave 1 quadrupole parameter meter also allows you to determine the complex transmission and reflection coefficients of the tested microwave quadrupole. To do this, a two-channel superheterodyne receiver 2 is disconnected from its ports 13 and 14, and the tested microwave four-terminal 15 is connected to them. Two reflectometers are used to determine the S-parameters of the four-terminal microwave 15, one of which is formed by a system of counter-connected directional couplers 7 and 10, and the other , similar, by a system of on-board directional couplers 8 and 11, the signals from the secondary channels of which are converted to a constant intermediate frequency, obtained as the difference between the frequencies of the signals from the generator pa test microwave signals 3 and the microwave oscillator 9 in vector voltmeter.

In position 1 of the first switch 4, when the direction of supply of the test microwave signal from port 13 to port 14 is measured, the complex coefficients of the scattering matrix of the tested microwave four-terminal 14: S, as the ratio of signals at the first and third inputs of the vector voltmeter 9, S ₂₁ , as the ratio of signals to the first and fourth inputs of a vector voltmeter 9.

In position 2 of the first switch 4, a test microwave signal is supplied from port 14 to port 13 and the complex coefficients of the scattering matrix of the tested microwave four-terminal device, S ₂₂ , are measured as the ratio of signals at the second and fourth inputs and as the ratio of signals at the second and third inputs of the vector voltmeter 9 .

Based on the foregoing, we can conclude that the proposed device has greater accuracy in measuring the complex transmission and reflection coefficients of microwave quadripoles with frequency conversion compared to the prototype. It allows you to measure their absolute complex parameters without any switching and reconnecting in the microwave paths.

Claims (2)

1. A device for measuring the absolute complex transmission and reflection coefficients of microwave devices with frequency conversion, containing the tested microwave four-terminal device, a microwave four-terminal parameter meter, consisting of a generator of test microwave signals, a first switch, a matched load associated with the first switch, microwave local oscillator, first, second, third, fourth directional couplers, vector voltmeter with output contact, first and second ports, tested microwave mixer, reference An RF mixer, a microwave generator, wherein the output of the test microwave signal generator is connected to the movable contact of the first switch, the first fixed contact of which is connected to the input of the main channel of the first directional coupler, the output of which is connected to the input of the main channel of the third directional coupler, the output of which is connected to the first port that is connected to the first input of the tested microwave mixer, the first input of the reference microwave mixer is connected to the second port connected to the output of the main channel directional coupler, the input of which is connected to the output of the main channel of the second directional coupler, the input of which is connected to the second fixed contact of the first switch, the outputs of the secondary channels of the first, second, third and fourth directional couplers are connected to the first, second, third and fourth inputs of the vector voltmeter, respectively the fifth input of which is connected to the microwave local oscillator, the output of the vector voltmeter is connected to the output contact, while the second inputs of the test and reference microwave the carriers are simultaneously connected to the output of the microwave generator, the first switch is connected to the matched load, characterized in that it additionally includes a phase locked loop, phase detector, first and second intermediate frequency mixers, second, third, fourth switches, a reference frequency generator, a comparator and a computer forming, together with the tested microwave mixer, reference microwave mixer and microwave generator, a two-channel superheterodyne receiver, while the output of the tested microwave mixer is connected inen with the movable contact of the second switch, the first fixed contact of which is connected to the first fixed contact of the fourth switch, the second fixed contact of which is connected to the first fixed contact of the third switch, the movable contact of which is connected to the output of the reference microwave mixer, the second input of the reference microwave mixer is connected to the second input of the tested microwave mixer, the output of the microwave generator and the second input of the phase locked loop, the first input of which is connected to the gene test microwave signal, the output of the phase locked loop is connected to the first input of the phase detector and the first input of the first intermediate frequency mixer, the output of which is connected to the second input of the comparator, the first input of which is connected to the output of the second intermediate frequency mixer, the first input of which is connected to the movable the contact of the fourth switch, and its second input is connected to the second output of the reference frequency generator and the second input of the first intermediate frequency mixer, the first output reference frequency for generators connected to the second input of the phase detector whose output is connected to the input of the microwave generator, the second fixed contacts of the second and third switches are interconnected, the comparator output is connected to the second input of the computer, a first input coupled to the output terminal of a vector voltmeter. 2. The device according to claim 1, characterized in that either the two-channel superheterodyne receiver or the tested microwave four-terminal, depending on the type of measurements, can be connected to the first and second ports of the microwave four-terminal parameters meter.