SU659995A1 - Arrangement for measuring amplitude-frequency characteristics of microwave time-delay lines - Google Patents

Description

This invention relates to the field of radio measurements.

A device for measuring amplitude-frequency characteristics (AFC) of quadrupoles is known, comprising a oscillating frequency generator, a mixer and an amplifier (as part of a receiver), a pulse generator, an oscillographic indicator 1.

However, this device does not provide sufficient measurement accuracy.

The closest in technical essence to the proposed is a device comprising a oscillating frequency generator, the input of which is connected to one of the outputs of the pulse generator. One of the inputs of the oscillating frequency generator is connected to the first input of the oscillographic indicator. The second output of the oscillating frequency generator is connected to the first inputs of the adder and one switch, the second input of which is connected to the second output of the pulse generator, and the third input of the mentioned switch is connected to the first output of the amplitude modulator, the input of which is connected to the output of the sinusoidal generator. The device also contains two controllable keys, the input of the first one is connected to the output of the mixer 2.

However, this device does not provide the necessary measurement accuracy.

The purpose of the invention is to improve the measurement accuracy.

This is achieved by the fact that the device containing the oscillating frequency generator, the input of which is connected to one of the outputs of the pulse generator, and one of the outputs is connected to the first input of the oscillographic indicator, the second output is connected through the three inputs of the adder and the first switch, the second input of which is connected to the second output of the emulsion generator, and the third input of the switch connects to the input of the amplitude modulator, the input of which is connected to the output of a sinusoidal generator torus, and two controllable keys, the input of the first of

which is connected to the mixer output, an additional switch, a low-frequency attenuator and a quadratic detector are introduced, the output of which is connected to the second input of the oscillographic indicator. The input of the quadratic detector is connected to the output of the second of the dented controllable keys, the second output of which is connected to the second input of the first controllable key, the output of which is connected via a low-frequency attenuator to

the first input of the second controlled key. The first input of the additional switch is connected to the output of the adder, the second input is connected to the second output of the amplitude modulator, and the output is connected to the input of the mixer. The third input of the additional switch is connected to the third input of the first controlled key, to the second input of the second controlled key and to the third output of the pulse generator, and the measured microwave delay line is connected between the output of the first of these switches and the second input of the adder.

The structural electrical circuit of the device is shown in the drawing.

The device contains an oscillating frequency generator 1, a three-digit power divider 2, an adder 3, switches 4 and 5, an amplitude modulator 6, a mixer 7, controlled keys 8 and 9, a low-frequency attenuator 10, a quadratic detector 11, an oscillographic indicator 12, a pulse generator 13, the generator of sinusoidal voltage 14. The drawing also shows the measured delay line 15.

The device works as follows.

The signal from the oscillating frequency generator 1, whose frequency varies according to the sawtooth law, is fed through a three-divider power divider 2 directly to the adder 3 and switch 4. During the first half-period of the saw-tooth modulation voltage, the switches 4 and 5 are controlled by signals from the pulse generator 13 whose frequency is equal to and synchronous to the modulation frequency, are interconnected through the test delay line 15 and the adder 3. As a result, two biases arrive from the output of the adder 3 via switch 5 to the mixer 7 drove, shifted in frequency by an amount determined by the delay time in the test line and the frequency tuning rate. The amplitude of the delayed signal is inversely proportional to the attenuation in the delay line. Since, where ROP and RIZM are the powers of the signals arriving at the adder directly from the three-divider power divider and through the tested delay line, respectively, the mixer 7 operates in the mode of simple linear frequency conversion. The signal of the beat frequency from the mixer through the controlled keys 8 and 9, which are also controlled by pulses from the pulse generator 13 and are directly connected to the given half period, and the quadratic detector 11 tuned to the beat frequency is fed to the oscillographic indicator 12, the sweep of which is synchronous with the change oscillator frequency generator frequencies 1. On the display screen

the frequency dependence of the attenuation in the delay line under study is written. During the second half-period of the modulation voltage, the switches 4 and 5 are interconnected via an amplitude modulator b, which receives a sinusoidal voltage from the generator 14 with a frequency equal to the beat frequency of the signal in the first half-period, and an amplitude sufficient for

obtaining an amplitude modulation factor of not more than 0.1. As a result, the signal is modulated with a small modulation factor (not more than 0.1) and is fed to mixer 7. The mixer in this half period

It works in the mode of detecting strong signals with a small modulation depth. And since the power at the carrier frequency (Pii) at the same time is equal to the ROP in the first half period and the condition that

where RB is the signal power at the side frequencies, the detection is equivalent to simple frequency conversion and the detection parameters coincide with the parameters of a simple frequency conversion.

With a known modulation factor, the signal from the output of the mixer 7 can be used as a calibration signal for a panoramic change. Modulation frequency signal through controlled keys 8 and 9,

which in this half-period are connected via a low-frequency attenuator 10 and a quadratic detector 12, goes to an oscillographic indicator. As a result, an electronic viewfinder is obtained on the screen and by changing the attenuation of the low-frequency attenuator 10, it can be combined with any AFC point of the delay line under study. With a calibrated amplitude modulation coefficient with an accuracy of

to the frequency non-uniformity of the attenuation of the three-dib power divider and the adder, as well as with a calibrated dependence of the amplitude modulation factor, on the low-frequency attenuator

10, it is possible to read the measured attenuation at any point in the frequency range.

Claims (2)

1. USSR author's certificate No. 445926, cl. G 01R 27/28, 1973. 2. The patent of Japan 43-3032, cl. PO DO, dated 08.16.66.