SU1282020A1 - Device for measuring absolute value and phase of reflection factor of microwave two-terminal network - Google Patents

Abstract

Invention ib. used in embedded automat. measuring systems. The purpose of the invention is improving the accuracy of measurements. The device contains microwave rc 1, four-impedance sensor 2 of impedance, communication connection 5-8 sensor 2, four-channel microwave switch 9, control unit (CU) 10, quadratic detector 11, band-pass filter 12 1st harmonic commutation frequency, amplitude detector (BP) 13, control voltage divider 21, indicator 22, phase meter 23, phase indicator 24, threshold unit 25, microwave two-port investigated 4. Controlled again Microwave phase shifter 3, two band-pass filters 14 and 17 of the 2nd harmonic of the switching frequency, BP 15 and 18, electronic switch 16, meter 1 9 relations BU 20. 1 Il. I with

Description

o

CX)

Yu

o you

one

The invention relates to a radio measuring technique and can be used in embedded automatic measuring systems.

The purpose of the invention is to improve the accuracy of measurements in the frequency band.

The drawing shows a structural electrical circuit of the device for measuring the modulus and phase of the reflection coefficient of a microwave two-pole network.

The device for measuring the modulus and phase of the reflection coefficient of a microwave two-pole device comprises a microwave generator 1, four probes of the impedance sensor 2, a controlled microwave phase shifter 3, and a microwave two-pole device under study 4. Communication elements 5-8 of the four probe sensors of the two resistances four-channel microwave switch 9, first control unit 10, quadratic detector 11, band-pass filter 12 of the first harmonic of the switching frequency, first amplitude detector 13, first band-pass filter 14 of the second harmonic of the 1C-1i frequency, second amplitude nsh detector 15, the electronic key 16, a second bandpass filter 17 of the second harmonic of the switching frequency, the third amplitude detector 18, the meter

19 ratios, second control unit 20, controlled voltage divider 21, indicator 22, phase meter 23, phase indicator 24, threshold unit 25.

Device for measuring the module

and the phase of the reflection coefficient of the microwave two-port operation works as follows.

The signal of a constant amplitude (11) from the microwave generator 1 is fed through the four probe probe 2 and the controlled microwave phase shifter 3 to the microwave two-terminal 4 under study.

The reflected wave interferes with the incident wave. The field distribution analysis is carried out using four communication links 5-8 of the four-probe sensor 2, placed in different sections so that the phase incursions between them are equal at the upper frequency of the range.

The four-channel microwave switch, according to the signal from the first output of unit 1, periodically switches at a frequency of 52 each of the output signals of the communication elements 5–8 of the five-probe probe 2 to the channel. In this case, the output, four-way microwave commutation

0

2

To torus 9, a signal is received in the form of a periodic sequence of radio pulses. This signal is detected by a square-law detector 11, the output of which is a periodic function.

The band-pass filter 12 tuned to the frequency SI separates the first harmonic of the output signal of the quadratic detector 11. The voltage output from the band-pass filter 12 is fed to the input of the first amplitude detector 13, the output voltage of which depends on the frequency, and its reduction from changes at a constant reflection coefficient.

The correction of the frequency dependence is carried out as follows.

The output of the quadratic detector 11 is fed to the input of the first band-pass filter 14 of the second harmonic, the output of which is detected by the second amplitude detector 15.

 The output voltage of the second amplitude detector 15 is determined by you

razheniem:

and to A.

that

ъ And

(one)

-

-

the transmission coefficient of the first band-pass filter 14 of the second harmonic at a frequency of 22;

the transmission coefficient of the second amplitude detector 15 ;.

 + B - amplitude of the second harmonic of the switching frequency;

a, bj are the coefficients of the decomposition in the Fourier series. The coefficient a is determined by

45

life:

2

 t

U (t) cos 2 5i tdt. (2)

The expression for U is:

In ККзК.1) ,, | „-I I

Sin

il

Cos

sin If

J & 2

(3)

where K is the proportionality coefficient.

It can be seen from formula (3) that the second harmonic appears only at hour 3

total disorder, and when fi D

0 since

ten,

 1, 2) - C

 Jr5 n cos --- - and.

But the voltage at the output of the second amplitude detector 15 depends not only on the frequency detuning

, ; j Jr J5 (the members of sinq ---: cos -). but also from about /

module I g | and the phase (member sin) of the complex reflection coefficient. In order to obtain information only about the frequency offset, the dependence on | r and f exclude.

Dp this output signal of the quadratic detector 11 is fed to the electronic key 16, which is controlled from the third output of the control unit 10, the electronic key opens only for the time when the voltage BJ, Bj appears on the output of the quadratic detector 11 (signals from elements 6 and 7 connections of the four-probe sensor 2). In this case, the output signal (U) of the electronic key 16 is a periodic function.

The second band-pass filter 17 of the second harmonic of the switching frequency allocates the second harmonic of the signal Ug (t). The output signal (U ,,,) of the second band-pass filter 17 is detected by the third amplitude detector 18, the output voltage of which is:

,

(four)

second transfer ratio

of the second harmonic band 17 filter at a frequency of 2y;

transmission coefficient of the third amplitude detector 18;

second harmonic amplitude

switching frequency, the reduction (4) has the form:

. | x

. Part I I

j (

, , 35/5 jrji. , .jsin (- sin4 (.

(five)

From the expression (5) it can be seen that the voltage at the output of the third amplitude detector 18 depends on the frequency

. ZZGV detuning (member --- - ---) from 8 8

blew | r | and the phases (the sin комплекс member) of the complex reflection coefficient of the microwave two-terminal 4 under investigation. Consequently, the signal, depending only on the frequency detuning, can be formed if you send C to the input of a divisible 19 ratio meter, and j to the divider input. Then the output voltage of the ratio meter 19, taking into account expressions (3) and (5), is:

I cos - tt iiSiiSi, J

-J T / -T / -1U- l 4)

14

. Js

sin ---- - (6)

where K is the transfer coefficient of the meter 19 relations. From the expression (6) it can be seen that the 2K.KK / K term is constant.

and a member of I sin cos -t- / sin (-o o / o

- I carries information about frequency- / 8

Noah detuning. Each value of the frequency in the operating range corresponds to a single value. cient

Jl.

eight

5iS cos --35

. f 3W n X

sin (-gg-)

0

a means and only value

. jiS of the sin coefficient ---.

The voltage from the output of the ratio meter 19 is supplied to the control unit 20, which sets the transmission coefficient of the controlled voltage divider 21 in accordance with the formula:

TO

Kc

ZRN

. lt &

sin - (7)

where KO is the transfer coefficient of the controlled voltage divider 21 at A (o (S 1). The output voltage of the controlled capacitor divider 21 of the voltage is:

55 and ,,,.

 is

 - cos 2 4 cos t -. (eight )

5128

This voltage is applied to the indicator 22, the scale of which is calibrated directly to the values | t |

From (8) it can be seen that the measurement error of the Koshm – spec module of the reflection coefficient is determined only by the frequency coefficient, i.e. In the proposed meter, the same measurement accuracy and broadband are achieved, as well as in the well-known, but without the introduction of a correction channel, which greatly expands its functionality, since it allows it to be used for

built-in control.

Voltage (U) from the output of the bandpass filter 12 is applied to the input of the phase meter 23, to the reference input of which the reference voltage is supplied from the second output of the unit 10.

The output signal of the phase meter 23 is applied to the indication of the phase 24, the scale of which is calibrated directly to the values of H.

If the phase of the reflection coefficient of the studied microwave two-terminal 4 is O, 180 ° or 360 °, then the voltage

and

ten

and, according to expressions (3) and

and

(5) are zero. The meter 19 relations, because of the zeros on both inputs, will not work. Therefore, there is an uncertainty in the definition of the frequency detuning. To eliminate this uncertainty, a threshold unit 25 and a controlled microwave phase - rotator 3 (discrete) are introduced into the meter. The signal (and j) from the output of the phase meter 23, in addition to the phase indicator, is fed to the difference between what and,. the purpose of improving the measurement accuracy of the frequency band, the first and second bandpass filters of the second

block 25, which, if the phase of research is 40 harmonics of the switching frequency, cereal

A microwaveable two-pole 4 is in the range of O - 5% 175 - 185% 355 - 360 °, produces a signal () that is fed to the control input of the controlled microwave phase switch 3. In this case, the phase shift introduced by the controlled The microwave phase shifter 3, 3 is amplified, for example, by

-g-, i.e. to the phase of the studied microwave two-pole is added a constant

TG value, equal to --45

50

2 With this voltage U

and ,, on

a tronny yutuyuch, second and third amplitude detectors, a ratio meter, a second control unit, a threshold unit and a controlled microwave phase shifter, while the inputs of the first and second band-pass filters of the second harmonic of the switching frequency are one directly and the other The electronic key is connected to the output of the quadratic detector; the control inputs of the electronic key are connected to the third output of the first control unit; the outputs of the band-pass filters of the second harmonic of the switching frequency with

The inputs of the meter 19 ratios are excellent, 55 bt respectively, through the second and third of us from zero. Thus, in full: the amplitude detectors are connected to the uncertainty in the determination of the frequency detuning.

the inputs of the meter relate, the output of which tiepes the second control unit

Dp of accurate determination of the phase of the reflection coefficient of the microwave two-pole 4 under investigation in this case follows from the indications on the indicator 24 phases, subtract

 2

The driver 3 is signaled, for example, by means of a LED, set-up. directly on the folder indicator 24 phase.

Controlled Microwave Condition5

0

five

Claims (1)

Invention Formula A device for measuring the module and the phase of the microwave reflection coefficient of a two-terminal device, containing a series-connected microwave generator, a four-probe impedance sensor, a four-channel microwave switch connected in series, the signal inputs of which are connected to the four-probe impedance sensor elements, a quadratic detector, a bandpass filter of the first harmonic of the switching frequency, first1) W amplitude detector, controlled voltage divider, indicator, phase meter, connected meter input to the output of the band-pass filter of the first harmonic of the switching frequency, the phase indicator connected to the output of the phase meter, and the first control unit, the first output of which is connected to the control (it is controlled by the four-channel CBCH controller, and the second output 35 the reference input of the phase meter, characterized in that, c. the purpose of improving the measurement accuracy in the frequency band, the first and second bandpass filters of the second 0 40 harmonics switching frequency, cereal a tron module, a second and a third amplitude detectors, a ratio meter, a second control unit, a threshold unit and a control of the microwave phase shifter, while the inputs of the first and second band pass filters of the second harmonic of the switching frequency are directly connected to one another and the output of the quadratic detector, which controls the input of the electronic key, is connected to the third output of the first control unit; the outputs of the band-pass filters of the second harmonic of the switching frequency, respectively, through the second and third volumetric detectors are connected to btvetstvenno-c the second and third amplitude detectors are connected to the inputs of the meter relate, the output of which tiepes the second control unit 712820208 It is connected to the control input of the maker, the input of which is connected to the voltage divider being controlled, to the full probe probe the input of the threshold unit is connected to the resistors, and the output is the output of the phase meter, and the output is connected to the control for connecting the input to the research input of the controlled microwave phase-induced .5 microwave two-port network.