SU1626194A1 - Device for measuring complex reflection coefficient of microwave two-terminal network - Google Patents

Abstract

This invention relates to radio measurements on microwave. The purpose of the invention is to simplify the implementation. The device contains a microwave generator 1, directional couplers 2 and 3, a valve 4, a two-terminal microwave 5 under study, other types of switches 6–8, a sylphase adders 9 and 10, a quadrature TV 1 1, with the load 12 and an indicator 13. Measurement and calibration are carried out with various combinations of On modes — Off consistent switches 6–8 are turned off, while reading indicator 13 and calculating the desired complex reflection coefficient. Since the non-ideality of the microwave components included in the device is integrally taken into account in the calibration process, high measurement accuracy is achieved without the use of precision and expensive microwave elements. 1 il. с Ј (I С о: tc ev 5 4

Description

to.

The invention relates to microwave radio engineering, in particular to measurements on microwave, and can be used to measure the complex reflection coefficient (FCC) of linear and non-linear microwave objects.

The aim of the invention is to simplify the implementation.

The drawing shows a structural-electrical circuit of a device for measuring the ECC of a two-port network SZCH.

The device contains a microwave generator 1 with an adjustable output signal level, the first 2 and second 3 directional couplers (BUT), valve 4, the two-terminal 5 spare parts under investigation, the first 6, the second 7 and the third 8 matched switches, the first 9 and the second 10 in-phase accumulators , quadratic divider 11, matched load 12 and indicator 13.

The device works as follows.

The harmonic oscillation of the generator 1 through the first HO 2, valve 4, the second HO 3 enters the input of the two-port 5 microwave being investigated. The oscillation proportional to the amplitude of the incident wave from the branch output of the first HO 2 through the first matched switch 6 arrives at the second input of the first in-phase adder 9. The oscillation proportional to the amplitude of the reflected wave coming from the branch output of the second HO 3 is divided by approximately equal quadrature divider I1. The oscillations from the outputs of the latter through the second coordinated switch actuator 7, the second in-phase adder 10 and through the third coordinated switch 8, the second in-phase divider 10, respectively, arrive at the first output of the first in-phase adder 9.

3 depending on the state of the agreed disconnectors 6 - 8, the indicator 13 is supplied with the following normalized oscillations: the agreed disconnectors 7 AND 8 NL /. READY IN THE STATE

Disabled, coi l.tov-tshshe 6 switches - in the Enabled state, then, X (t) UcosO.,

where U, (0 is amp. III rvrt 1 and the oscillation frequency of the corresponding r-nio, consistent disconnects, and 3 are in the Vi and POMRI state, the i-h

switch 7 is in the On state, then

C, cosdyt + C) +

cos (iOt -f (ft),

(2)

C, - amplitude oscillation first

harmonics;

C is the oscillation phase of the first harmonic with respect to X (t);

G.

J1

Qb - amplitudes and phases of higher harmonics;

N is the number of higher harmonics, the matched switches 6 and 7 are in the Disable state, the matched switch 8 is in the On state, then

Y2 (t) qC, cos (Qt + (| 7 + ()

N + C2; cos (i (0t ty;),

one

where qC is the amplitude of the first harmonic; q is the coefficient taking into account the non-uniformity of the division of the amplitude of the input signal by the quadrature divider 11;

C) - phase shift introduced

quadrature divider 11 on the first harmonic; Co | - amplitudes of higher harmonics; v); - phase shifts introduced by quadrature divider 11 at higher harmonics,

the matched switches 6 and 7 are in the On state, the matched switch 8 is in the Off state, then

Z, (t) X (t) + Y4 (t), (4)

the matched switches 6 and 8 are in the On state, the matched switch 7 is in the Off state, then

Zt (t) X (t) + Yu (t). (5) When an indicator, representing a wattmeter, is applied to the input, the signals (1) - (5), its readings are respectively

(6) (7) (3)

162

P4 Ua / 2 + cf / 2 +

+ EC, SozP + Pr,, (9)

P5 UZ / 2 + +

+ qUC, cos ((f + C /) + Prg, (10)

where Pr (P r2. total power of higher harmonics.

From the relations C9) and (10), taking into account (6) - (3), we express the following values:

(| (P4-P2 P,), (11)

C, sinq (P + P, - P +

+ qC (cos07cos (j)) / J2p7qsin (f ;. (12)

Since the microwave path is not ideal, the first harmonic of oscillation YjCt) is proportional to the linear combination of the first harmonics of the incident a. and reflected b4 waves

C, -j-a, + pb,. (13)

The oscillation coming from the branch output of the first HO 2 is proportional to the amplitude of the incident wave.

U -cU. (14)

We divide (13) by (14) and, from the obtained relation, we express the desired ECC (G C / a,) of the bipolar circuit under study 5

Г К, С, / U - Ке,

(15)

where K, tf / f3, K2 tf // 3-gauge constants; the ratio C / U is calculated by the formula

C / U.- С (СОО) + JC sin (/ / 42p7,

4 (16)

where j is -1.

To determine the calibration constants K (and K-, calibration is performed. For this purpose, instead of the studied two-terminal network, two model linear loads are connected in turn with known ECCs (and G, the powers P are measured (-P5 and the ratios (C / U) are calculated. And (/ V) B s ° according to (16).

For one of the loads, for example for the first one, the value of q is calculated from (7) and (8), taking into account the fact that Pr Pr%, the value of q, which is equal to q l | P $ / P2.

(17)

1626194

In addition, a supplementary measurement is carried out when the gigantic otkopyuchatel :: 1 and 8 are switched on and the disabled one is turned off 6. The indicator 21 is in this case equal to

Р6 - + q2cf / 2 + qcfcostf, 084 о; кудч exact value ф

V ± arccos F (P6 - Pz - P,) / 2- | ivPs j

 O9)

where the sign is chosen according to the approximate known value ($.

Writing the relation (15) for each exemplary load, we obtain a linear system of equations with dumum unknowns K and .... Having resolved this system with respect to K and K, we obtain

TO.

G - g

(th / iG)

K2 K, (C / U) 2 - G2,

(20) (21)

where the ratios (C / U) are calculated by the formula (16) for each exemplary load.

When measuring, the values of q, y and K1, KЈ are considered known.

When measuring QCDs of nonlinear microwave objects, it is required to know the level of the incident wave a, /. With this, one-third of the calibration constant K is connected when connecting, instead of the two-terminal circuit 5, an exemplary wattmeter. The reference power meter reading 0 is related to the level of the incident wave / a0 | by ratio

/ S / l | 2Р07 (Нg7Р), (22)

where KKO is an exemplary wattmeter Gd determined by formula (15).

Express from (14) the value of / g, / taking into account (6)

/&,/.- () where.

Substituting in (23) instead of a value / av /, we define K, which allows, by reading P, of a wattmeter to control the level of the incident wave.

The imperfection of the microwave nodes that are part of the QCO device for measuring the microwave microwave two-pole is taken into account integrally in the calibration procedure, which provides increased measurement accuracy without the use of precision and expensive microwave elements,

Claims (1)

Invention Formula A device for measuring the complex reflection coefficient of a two-pole microwave, containing a series-connected microwave generator with an adjustable output level, the first directional coupler, to the output of the incident-oriented secondary channel of which the first matched switch is connected, and the gate, the second directional coupler, the output of the primary channel which serves to connect the microwave bipolar circuit under study, and to the output of the secondary channel oriented to the reflected wave key divider, the first adder, the output of which is connected to five 0 the first input of the second adder, and the output of the last one - with the indicator input, and the second matched switch, differently so that, to simplify the implementation, the output of the first matched switch is connected to the second input of the second adder, the input of the second directional coupler with the output of the valve, and to the output wave-oriented output of its secondary channel the entered matched load is connected, the first output of the divider is connected to the first input of the first adder via the second matched disconnect spruce, and the second output of the divider is connected to the second input of the first adder through the input of the third matched switch, and the divider is made quadrature, and the adders - in-phase.