SU949547A1 - Device for measuring four-terminal transmission factor - Google Patents

Description

The invention relates to a radio measuring technique and can be used to measure the transmission coefficients of two-frequency microwave quadrupoles operating in a wide frequency range. A reflectometer is known that contains two directional couplers and two detector heads 1. The disadvantages of this device are the non-amplitude -: frequency characteristics of directional couplers and detector heads, as well as the need to stabilize the power of the microwave generator, which does not provide high measurement accuracy in a wide frequency range. It is also known a device for measuring the coefficient of the microwave transfer of a quadrupole, which contains a microwave generator, a controlled attenuator, a power divider and a power adder, two controllable keys, a detector, an electronic switch, an automatic power control unit and an indicator. The essence of the work is that the reference and the measured channel are alternately connected to the detector and the input signal of the detector is synchronized but switched to an automatic power control (APM) system and an indicator. When the frequency of the microwave generator is tuned, its power is maintained by a constant ARM system around, some average value of C2. However, the result of the measurement depends on the inconsistency of the crosstalk attenuations of the divider and the power adder in the frequency range and on the change in power relative to the average value, which does not provide accurate measurements in the working frequency range. Thus, the error in measuring the transmission coefficient is ± 0.1 dB, which is a significant value even for rough measurements. The purpose of the invention is to increase the measurement accuracy over a wide frequency range. The goal is achieved in that a device for measuring the transmission coefficient of microwave quadrupoles, containing an indicator, a microwave generator, an output connected to the input of a power divider, two directional couplers, two controllable switches, the control inputs of which are connected to the corresponding outputs of the control unit, and the inputs - with the corresponding outputs of the first directional coupler, the output of the first controlled switch is connected to one of the input terminals of the device, and the output of the second controlled switch with ne The second input of the second directional coupler, the second input of which is connected to another input terminal of the device, and the first output to the detector input, has been entered, two switching keys, a second detector and a solver, and the input of switched keys is connected to the corresponding output of the power divider, control input switched keys Connected to the corresponding output of the control unit, and the output of switched keys connected to the corresponding input of the first directional coupler, the second output of the second directional signal tvitel, via a second detector coupled to the first vhrdom deciding unit, a second input of which is connected to the output of said detector, and an output - to the input of the indicator.

The drawing shows a block diagram of the device. I

The device contains a microwave generator 1, a power divider 2, switched keys 3 and 4, four-arm directional couplers 5 and 9. Controllable i. Switches b and 7, measured four, pole 8, detectors 10 and 11, decisive unit 12 , indicator 13, control unit 14 and input terminals 15 and 16.

The device works as follows.

The device operates cyclically in four cycles and is based on alternating switching of switching keys 3 and 4 and controlled switches b and 7, storing the output voltages of the detectors. 10 and 11 in each cycle and processing these voltages in the solver unit. Synchronous control of the keys 3 and 4 and the switches b and 7 is carried out from the control unit 14. Open state of keys 3 and 4 and switches B and 7 is carried out in the following sequence: 1 cycle - 3 and b, P cycle - 4 and b AND cycle - 3 and 7, 1st cycle - 4 and 7. Switched keys 3 and 4, the directional connection of the microwave generator 1 to the reference and measurement channels is carried out. The measured quadrupole with an unknown coefficient of transfer factor K is turned on in the measuring channel. The controllable switches b and 7 alternately connect the reference and measurement channels to detectors 10 and 11. Thus, in four cycles of operation of the keys and switches at the outputs of the detectors 10 and 11, eight signals are generated and stored in a crucial block.

In the first measure

1 Ch1o (EKt KzK5K (, K9)

(-, q-t-i (EK,.,. K, K) "

(U-l) - m, 1 In the second cycle

(Uio) a qJEKJi K KUeKg;

{li.- I ci / V v L-i / V

(0, v) i qi; (E4 K9

In the third bar

(J-fo) s ChKKhKd) (° l)).

in the fourth bar

Tom tact

q, o (EK; K4K5K-rKxK9 ft (10) +} H.

(and)

where KP is the transfer coefficient of the constituent units;

The measured quantity, n is the number of the corresponding b. In the decision block, the received stresses are processed in accordance with the following mathematical expression:

l 4rilVi 13Chl f /n.nn.tVi "

    mo) 44u., kls

and -,. b ewTCN | (0, o) - ((Uiok (u-n) i

K., LKh, k.

where b is the proportionality coefficient.

The output signal of the device depends on the ratio of the transmission coefficients of the controlled switches 6 and 7 in the open state and does not depend on the power of the microwave generator and the frequency characteristics of the elements in the microwave path.

. The measurement error is determined only by the incomplete ratio of the transmission ratios of the controlled switches b and 7 and does not depend on the magnitude of the measured transmission coefficient. Taking into account that the direct axis;} key loss is 0.30, 7 dB, and the spread of non-identicalness of attenuation is a fraction of the direct attenuation, their ratio will be close to unity. For example, Oskin-type keys produced are non-identical transmission coefficients of ± 0.15 dB, and their ratio is 1.035. At this, the measurement error is ± 0.15 A or ± 3.5% and does not depend on the magnitude of the measured transmission coefficient. If you pick up an identical pair of controlled keys by damping, the error can be reduced to zero. The advantages of the proposed device are simpler selection of keys for attenuation (than, for example, selection of identical coupler-G4 detector pairs in existing instruments such as the P2-23 reflectometer), manufacturability, lack of adjustment and tuning elements.

Claims (2)

Invention Formula A device for measuring the transmission coefficient of the microwave four-sided arresters, containing an indicator, a microwave generator, an output connected to the input of a power divider, two directional-couplers two controllable switches, the control inputs of which are connected to the corresponding outputs of the control unit, and the inputs corresponding outputs of the first directional coupler, the output of the control switch is connected to one of the input terminals of the device, and the output of the second controlled switch is connected to the first input of the switch The second input is connected to a different input terminal of the device, and the first is connected to the detector input, which means that, in order to improve measurement accuracy in a wide frequency range, two switched keys are introduced into it, wto a swarm detector and a solver unit, while the input of switched keys is connected to the corresponding output of the power divider, the control input of the switched keys is connected to the corresponding output of the control unit, and the output of the switched keys is connected to the corresponding input of the first directional coupler, the second output of the second directional coupler through the second detector connected to the first input of the decision block, the second stroke of which is connected to the output of the said detector, and the output to the indicator input. Sources of information taken BO attention during the examination 1. The yard bus B.V. Radio measurement. M., 1978, p. 319. 2. Journal of Instruments and Experimental Technique, 6, 1979, p. 113 (prototype)