SU1718143A1 - Microwave resonator bandwidth meter - Google Patents

Abstract

The invention relates to a radio metering technique on a microwave and can be used to measure bandwidth, quality factor, dielectric constant and dielectric loss of substances. The purpose of the invention is to increase speed. Introduction of a frequency doubler 13, a dual frequency meter 14, a clock pulse generator 15, a control voltage generator 16, an adder 17, a comparator 18, and their connections eliminates the manual tuning of the modulating signal generator 8 to a frequency F equal to half the band pass the resonator 1 under study, exclude the manual operation of switching the low-frequency filter output 10 to the input of the generator 8, exclude the operation of recalculating the values of D f0 to 2D f0, a as well as calculating the Q factor of the resonator 1. 1Cp. f-ly. 4 il.

Description

fot.1

The invention relates to a radio metering technique and can be used to measure bandwidth, quality factor, dielectric constant and dielectric loss of substances.

A device for measuring the bandwidth of a microwave resonator is known, which comprises a microwave generator, a microwave resonator under investigation, an indicator.

However, this device does not have high performance measurements.

The closest to the technical essence of the present invention is a device for measuring the bandwidth of microwave resonators. containing a microwave generator connected in series, a microwave resonator under study, a microwave detector, an amplifier, a frequency doubler and a phase detector, a series-connected DC-amplifier, a low-pass filter and a zero indicator, a second modulated frequency generator connected in series output connected to the second input of the phase detector, the output of which is connected to the input of a DC amplifier, a frequency meter, an input connected to one of the outputs of the modulating signal generator, oh whose output is connected to the input of modulation of the microwave generator tion. the third output is connected to the input of the second frequency doubler, an automatic frequency control unit connected between the second output of the microwave detector and the frequency control input of the microwave generator, the second output of which is connected to the resonant frequency indicator, a switch, the first input connected to the output of the low-pass filter, the second the input is with a common bus, and the output is with a modulating signal generator.

However, the known device does not provide high measurement performance due to the presence in the measurement process of manual operations of controlling the frequency of the modulating signal generator, control of the switch, as well as operations for calculating the bandwidth and quality factor of the resonator under study.

The purpose of the invention is to increase the measurement speed.

The goal is achieved by connecting a third frequency doubler and a two frequency ratio meter connected in series to a microwave resonator bandwidth meter, another input connected to the second output of the microwave generator, connected in series to a clock generator, a control voltage generator and an adder , the second input connected to the output of the switch, and the output connected to the control input of the generator of the modulating signal, the comparator, the first input connected to go low frequency filter, the second - to a common bus, and output - to the control inputs of the oscillator control voltage and a switch, wherein the third output gene0 Rhatore baseband signal is connected to the third input of a frequency doubler. In this case, the control voltage generator contains an integrator, three electronic switches, a resonator and a power supply terminal,

5 control input of the first key is connected

with the first input of the control generator

the voltage and control input is to rub its key, the first output of which is connected

with the first input of the integrator, and the second output with the second input of the integrator and through the connected second switch and the resonator with the power supply terminal, the control input of the second switch is connected to the second input of the control voltage generator,

5, the outputs of the first switch are with the corresponding inputs of the integrator, the output of which is connected to the output of the control voltage generator.

Comparison of known device with

0 suggests that the proposed device exhibits new technical properties expressed in improving the measurement performance by eliminating the manual operation of setting up the modulating signal generator, controlling the switch, as well as computational operations to determine the bandwidth and quality factor of the measurement. Microwave resonator. .

0 FIG. 1 shows a block diagram of a device for measuring the bandwidth of microwave resonators; in fig. 2 - block diagram of the automatic frequency control unit; in fig. 3-structure

5 is a control voltage generator circuit; in fig. 4 - oscillograms of control voltages.

The device for measuring the passband of the microwave resonators contains in series a microwave generator 1, a microwave resonator 2, a microwave detector 3, an amplifier 4, a frequency doubler 5 and a phase detector 6, a second doubler 7, the output connected to the second input of the phase detector 6. The generator 8 of the modulating signal, the first output connected to the control input of the microwave generator 1, the second output connected to the input of the second frequency doubler 7, connected in series to the amplifier S constant

current, low-pass filter 10 and switch 11, automatic adjustment unit 12, an input connected to the second output of the microwave detector 3, and an output connected to the frequency control input of the microwave generator 1, connected in series to the third frequency doubler 13 and frequency ratio meter 14, to another input connected to the second output of the microwave generator 1, connected in series a generator of 15-stroke pulses, generator 16 of the control voltage and adder 17, connected to the output of the switch 11 by the second input, and connected to the output the control input of the generator 8 of the modulating signal, a comparator 1B, the first input connected to the output of the low-frequency filter 10, the second input to the common bus, and the output to the control inputs of the generator 16 of the control voltage and switch 11, and the third output of the generator 8 of the modulating The signal is connected to the input of the third frequency doubler 13.

The block 12 automatic frequency control (AFC) contains the amplifier 19 signal Errors, the input connected to the input of the AFC 12, phase detector 20, the first input connected to the output of the amplifier 19, the phase shifter 21, the output connected to the second input of the phase detector 20, modulating generator 22, output connected to the input of the phase shifter 21. DC amplifier 23, the input connected to the output of the phase detector 20, low pass filter 24, the input connected to the output of amplifier 23, and the output to the input of the modulating generator 22 and the output of the AP H 12.

The control voltage generator 16 comprises an integrator 25, electronic switches 26-28, a resonator 29 and a power supply terminal 30, the first switch 26 being connected parallel to the capacitor of the integrator 25, the second switch 27 connected between the resistor 29 and the inverting input of the integrator 25, the third switch 28 connected between the inverting and non-inverting inputs of the integrator 25, the control inputs of the first 26 and third 28 keys are connected to the first input of the generator 16, and the control input of the key 27 is connected to the second input of the generator 16.

A device for measuring the bandwidth of microwave generators operates as follows.

Depending on the position of the controls of the meter 14 frequency ratio, which is used as a commercially available electronic

frequency meter, the meter can operate in three modes: the measurement mode of the resonant frequency of the microwave resonator 2; bandwidth measurement mode 5 of the microwave resonator 2 (measurement of the frequency of the signal from the output of the third frequency doubler 13; the ratio mode of the resonant frequency of the microwave resonator 2 and the frequency of the signal at the output of the frequency doubler 13 (measurement of the microwave resonance 2).

In the mode of measuring the resonant frequency of the microwave resonator 2, the AFC unit 12 is turned on and the microwave generator 1 is tuned to the resonant frequency of the resonator under test 2.

Block AFC 12 operates as follows.

A modulating oscillator 2 2 frequency modulates a microwave generator

0 1, while the frequency of the modulating oscillator 22 is constant. System - investigated. Microwave resonator 2 - microwave detector 3 - performs non-linear conversion of the frequency-modulated signal

5 microwave generator 1, as a result, the modulation frequency and its multiple frequencies are extracted on the microwave detector 3 load, and the modulating frequency signal (operating signal) changes the sign of the microwave generator 1 relative to the microwave resonator under study 2 em phase 180 ° (passes through zero). After amplification in the amplifier 19 of the error signal, the working signal is fed to the input of the phase

5 of the detector 20, to the second input of which a signal of the modulating oscillator 22 (reference signal) is supplied through the phase shifter 21. At the output of the phase detector 20, an error signal is generated, which through the DC amplifier 23 and the filter 24 is fed to the control input of the microwave generator 1, adjusting it to the resonant frequency of the investigated microwave resonator 2. When the AFC 12 operates, the frequency of the microwave generator

5 1 is maintained equal to the resonant frequency of the microwave resonator under study 2.

The generator 1 in the control voltage operates as follows.

The signal from the generator 15 clock pulses UI-ti (Fig. 4a) is fed to the first input of the generator 16 of the control voltage and then to the electronic switch 26 connected in parallel to the capacitor of the integrator 25. At the same time it is fed

5 to key 28. As a result of the closure of the keys 26, 28, the capacitor discharges, the inputs of the integrator 25 are closed, and at the output 20 a signal equal to zero appears. In this case, the key 27 is closed. After the termination of the pulse UfTH generator 15 keys 26,

28 is opened and the voltage at the output of the integrator 25 UryH (Fig. 46) increases linearly. At the time of the appearance of the UKOMO signal (Fig. 4d) of a single level at the second input of the generator 16 (from the output of the comparator 18), the key 27 is opened, and the voltage UryH remains unchanged until the next pulse Ur ™ arrives. In the following, the process is repeated.

In the bandwidth measurement mode, the meter operates as follows.

A clock pulse generator 15 generates a periodic sequence of square-wave Ur ™ pulses, which are fed to the input of the generator 16 control pulses and trigger it. As a result, a linearly increasing signal Ur / n appears at its output. which through the first input of the adder 17 is fed to the control input of the generator 8 of the modulating signal. The signal Ukont at the output of the comparator 18 is equal to zero, therefore, the switch 11 is in the state when the common bus is connected to the second input of the adder 17. The generator begins to tune in frequency. The signal from the output of the oscillator 1, modulated in amplitude, is fed through the microwave resonator 2 to the input of the microwave detector 3. The detector 3 detects this signal, and as a result, the output voltage of the envelope signal 1)

U3 Umicos {2 Ft-y5), (1)

tgp F / Afot (2)

where Ua is the voltage of the envelope signal;

Umi is the amplitude of the envelope signal at the input of amplifier 4;

F is the frequency of the modulating signal;

DGo is half the passband of the microwave resonator 2 under study;

p is the phase shift of the envelope of the microwave signal relative to the modulating signal.

The signal Us is amplified in amplifier 4 and fed to the first frequency doubler 5. The output signal doubler 5 frequency

Us KUmi cos {4 ftFt - 2 ft,

(3)

where K is the conversion factor.

At the output of the second doubler 7 frequency signal has the form

Ui KUm22cos (47rFt), (4)

where Um2 - the amplitude of the signal at the second output of the generator 8.

The signals Us, U are fed to the phase detector 6, the output voltage of which

U6 K6K2Um12 Um22COS2. {5} where Kb transmission coefficient of the phase detector 6.

After amplification in the amplifier 9 through the filter 10, this ifnch signal (FIG. 4c) (error signal) is fed to the switch 11 and the comparator 18.

Oscillator Frequency Tuning 8

occurs until the ifnc signal at the output of the filter 10 reaches zero. In this case, the frequency of the modulating signal F will be equal to half the bandwidth of the resonator 2 under investigation, as follows from expression (2) and formula (5)

. (6)

At the moment of fulfillment of the condition (6), the comparator 18 is triggered and at its output appears the signal of the SINGLE LEVEL UKOMR, which is fed to the second control input of the generator 16 of the control voltage and to the control input of the switch

11. Under the action of this signal, the voltage at the output of the generator 16 ceases to increase and remains constant until the next clock pulse arrives from the generator 15, and the switch 11 gives a signal

If the output of the filter 10 to the second input of the adder 17, which, sums the signal of the generator 16 with the signal of the filter 10. As the meter has a certain setting band, as a result

the sum signal of the generator 8 is precisely tuned to the frequency F. It is obvious that the signal at the output of the phase detector b changes sign according to (2) and (5) at (p 45 ° L) at this moment condition (6) is fulfilled.

The signal from the third output of the generator 8 is supplied to the frequency doubler 13. The voltage from the output of the frequency doubler 13 with a frequency of 2Af0 is applied to the meter 14, which measures the pass band

Microwave resonator 2.

In the Q-mode, the meter operates as follows.

The meter 14 is set to the two frequency ratio mode. On one of his

the inputs receive a microwave signal from the output of the generator 1, and to the other - the voltage from the third frequency doubler 13.

The operation of the device for measuring the bandwidth of the microwave resonators in the mode

Q measurement does not differ from its operation in the two previous modes. The quality factor value, like the other two parameters, is taken from the digital indicator of the frequency ratio meter.

Thus, the introduction of the third frequency doubler, frequency ratio meter, clock generator, control voltage generator, adder and comparator into the bandwidth measurement device of the microwave resonator eliminates the manual tuning of the modulating signal generator at 5 frequency F, eliminating the manual switching operation output of the low-frequency filter to the input of the modulating signal generator, exclude the operation of converting the Af0 value to 2Af0, as well as the operation of calculating the quality factor using the formula

"Trez

Q-TA1T

which allows to increase the measurement speed, and this is what achieves the goal.

The spectrum of the microwave signal of generator 1 contains the carrier of the microwave signal, two antiphase satellites (FM modulation with a small index), ± ± Рнм from the carrier, two common-mode satellites (AM modulation), ± Ram

On the microwave detector 3, the frequency of the RChm is allocated (the error signal, this signal vanishes during the operation of block 12), the frequency of Ram (the signal is used in the measurement system of the passband of the microwave resonator under investigation 2), the frequency of the Ram ± RChm {easy to show that when tuning the microwave generator 1 to the resonant frequency of the investigated microwave resonator 2, these signals turn into

ZERO) ..:.,.

In order for the block 12 to be compatible with the microwave passband measuring device in question, the RFI Io condition must be fulfilled or, if the passband of the microwave resonator 2 under study changes for any reason (for example, due to the introduction of the test sample) the limits of variation of half of the passband of the microwave resonator under study 2. When the block 12 is correctly tuned, the frequency signal Rfm that hits the phase detector 20 does not affect its operation, since the phase detector 20 integrates the signals of all frequencies other than RCM. For better isolation, you can perform the amplifier 19 of the error signal with a band pass (for frequencies

RHM).

Claims (2)

1. An apparatus for measuring the passband of a microwave resonator, comprising a VHF generator connected in series, a microwave resonator, a microwave detector, an amplifier, a frequency doubler and a phase detector. tector, second frequency doubler, output connected to the second input of a phase detector, modulating signal generator, first output connected to a control input of a microwave generator, second output connected to a second frequency doubler input, connected in series with a DC amplifier, low pass filter and switch , the second input connected to the common bus, the automatic frequency control unit, the input connected to the second output of the microwave detector, and the output connected to the input of the frequency control of the microwave g generators of, the output of the phase detector is connected to the input of the DC amplifier, wherein. that, in order to increase the measurement speed, a third frequency doubler connected in series and a two frequency ratio meter, another input connected to the second output of the microwave generator, were introduced into it. connected in series a clock pulse generator, a control voltage generator and an adder, a second input connected to the switch output, and an output connected to the control input of the modulating signal generator. comparator, the first input connected to the output of the low-frequency filter, the second input to the common bus and the output to the control inputs of the control voltage generator and the switch, with the third output of the modulating signal generator connected to the input of the third frequency doubler. 2. The device according to p. T, which is that the control voltage generator contains an integrator, three electronic switches, a resonator and a power supply terminal, the control input of the first switch is connected to the first the input of the control voltage generator and the control input of the third key, the first output of which is connected to the first input of the integrator, and the second output to the second input of the integrator and through the connected second key and resonator to the power supply terminal, the control output of the second key connected to the second input generator channeling guide voltage, the first switch outputs connected to respective inputs of the integrator, whose output is connected to the output of the generator control voltage. 24 i-generator I 3t from microwave dkvktora 3 L FIG. 3 ®ig Z GUN ) Yw fl No   I FIG. four