RU2235336C1 - Uhf power measuring device - Google Patents

Abstract

FIELD: radio-measuring equipment engineering.

SUBSTANCE: device has thermo-converter, signals from which are sent to inputs of four electronic keys. Onto control inputs of keys impulses from outputs of displacement register are sent. To informational input of displacement register impulses from means for dividing frequency in four are sent, and on step input - signal from impulse generator. From outputs of electronic keys signals are sent onto inputs of two low frequency amplifiers, on outputs of which amplified bipolar signals are formed. Then signals are sent to inputs of two pass-band filters, after that they are converted to direct current in two synchronous detectors and are summed by adder.

EFFECT: higher sensitivity of measuring device, as well as such a ratio of signal/noise, which positively affects measurements precision.

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Description

The invention relates to a radio engineering and can be used to measure the power of ultra-high frequencies (microwave).

A device for measuring small levels of microwave power according to the copyright certificate SU No. 678435, G 01 R 21/04, containing a thermocouple, a source of reference DC voltage connected to one of the inputs of the operational amplifier, an indicator, an alternator connected between the output of the operational amplifier and an indicator input, the second output of which through an AC filter is connected to a thermal converter connected to the second input of the operational amplifier through a low-pass filter. The disadvantage of this device is the high noise level and, as a consequence, the low sensitivity and accuracy of measurements at low microwave power levels. This is because the operational amplifier used to amplify small levels of constant voltage has, at detuning frequencies close to zero, a high level of flicker noise decreasing inversely with the detuning frequency to frequencies lying in the region of units of kilohertz.

The device described in the book of M.I. Bilko et al. Microwave power measurement. M .: Sov. Radio, 1976, p.65, containing a series-connected thermal converter, an electronic switch, a low-frequency amplifier (ULF), a phase detector, a direct current amplifier (DC), the output of which is the output of the device, and a pulse generator, two outputs of which are connected to the control inputs electronic key and phase detector. The disadvantage of this device is the low sensitivity and reduced measurement accuracy at low levels of microwave power.

The closest analogue is the device described in the book of M.I. Bilko et al. Microwave power measurement. M., Sov. Radio, 1976, p. 65.

To increase the sensitivity and accuracy of the measurement, a microwave power meter is proposed, containing a thermocouple connected in series, the input of which is the input of the device, an electronic key and a low-frequency amplifier, as well as a synchronous detector, a DC amplifier, the output of which is the output of the device, and a pulse generator, characterized in that the second, third and fourth electronic keys are inserted into it, connected in parallel along the signal input with the first electronic key, sequentially connected the second low-frequency amplifier, the direct input of which is connected to the output of the second electronic key, and the inverse input is the output of the fourth electronic key, the first bandpass filter, the second synchronous detector, adder, the output of which is connected to the input of the DC amplifier, the second bandpass filter, input which is connected to the output of the first low-frequency amplifier, and the output to the input of the first synchronous detector, with the direct input of the first low-frequency amplifier connected to the output of the first electronic key, and the inverse input od - with the output of the third electronic key, and the second input of the adder connected to the output of the first synchronous detector, as well as the first frequency divider in two, the second frequency divider in two, logic element I and a shift register, four outputs of which are connected to the control inputs of four electronic keys, and the output of the pulse generator is connected to the clock input of the shift register and the input of the first frequency divider by two, the second input of the logic element AND is connected to the output of the first frequency divider two, third and fourth bandpass filters whose inputs are connected to first and second outputs of the shift register, and outputs - to the second inputs of the first and second synchronous detectors, respectively.

Figure 1 shows a diagram of a device; figure 2 - timing diagrams of the operation of the device.

Figure 1 shows:

1 - thermal converter,

2, 3, 4, 5 - the first, second, third and fourth electronic keys, respectively,

6, 7 - the first and second low-frequency amplifiers, respectively,

8, 9, 10, 11 - the first, second, third and fourth band-pass filters, respectively,

12, 13 - the first and second synchronous detectors, respectively,

14 - adder

15 - UPT,

16 - pulse generator,

17, 18 - the first and second frequency dividers into two, respectively,

19 - a logical element And

20 - shift register.

Figure 2 shows:

a, b, c, d - time diagrams of voltages from the outputs of the switches 2, 3, 4 and 5, respectively,

d, e - timing diagrams of the signals from the outputs of ULF6 and ULF7, respectively.

The microwave power meter contains a temperature converter 1, first 2, second 3, third 4 and fourth 5 electronic keys, the first 6 and second 7 ULF, the first 8, second 9, third 10 and fourth 11 band-pass filters, the first 12 and second 13 synchronous detectors, the adder 14, UPT 15, the pulse generator 16, the first 17 and second 18 pulse frequency dividers by two, a logical element And 19, the shift register 20.

The microwave power meter works as follows. The low-level direct voltage from the output of the thermal converter 1 is supplied to the signal inputs of electronic keys 2, 3, 4, and 5, to the control inputs of which pulses from the outputs of the shift register 20 are shifted to each other by a quarter of the period. The information input of the shift register 20 receives pulses of the form of FIG. 2a from a frequency divider into four, formed by successively connected first 17 and second 18 frequency dividers into two and a logical element And 19, and to the clock input - a signal from the output of the pulse generator 16. From the outputs the first 2 and third 4 electronic keys, the signals are fed to the direct and inverse inputs of the first VLF 6, and from the outputs of the electronic keys 3 and 5, the signals are sent to the direct and inverse inputs of the second VLF 7, respectively, at the outputs of which amplified bipolar signals shown in fig.2d and e. Then the signals are fed to the inputs of the first 8 and second 9 bandpass filters, designed to convert the pulse signal into a sinusoidal and clean from interference.

After that, the sinusoidal waveforms are converted to direct current in the first 12 and second 13 synchronous detectors and summed on the adder 14. UPT 15 produces the final amplification of the DC signal to the level necessary for the operation of the indicator device.

To obtain the reference signals acting on the second inputs of the first 12 and second 13 synchronous detectors, the signals from the first and second outputs of the shift register 20 are used after conversion to a sinusoidal voltage by the third 10 and fourth 11 bandpass filters.

As can be seen from fig.2d, e at the outputs of the ULF 6 and ULF 7 in comparison with the analog signal is generated doubled amplitude, at the same time, the noise level of these amplifiers remains at the same level. Due to this, a gain in signal-to-noise ratio and an increase in the sensitivity of the meter are obtained. In addition, an additional gain in signal-to-noise ratio and, accordingly, in sensitivity is obtained due to the fact that at the output of adder 14 the useful DC signal is doubled, and the noise of the ULF 6 and synchronous detector 12 on the one hand and VLF 7 and synchronous detector 13 on the other hand, when summed, they increase by only 1.42 times. This is because the noise of these devices are uncorrelated random processes.

Thus, with the same level of the microwave input signal, the claimed device allows, approximately, three times to increase the sensitivity of the device and significantly increase the measurement accuracy.

All elements of the device can be performed on a standard element base and do not have any features.

Claims (1)

A microwave power meter containing a series-connected thermocouple, the input of which is the input of the device, an electronic key and a low-frequency amplifier, as well as a synchronous detector, a DC amplifier, the output of which is the output of the device and a pulse generator, characterized in that a second, third and a fourth electronic switch connected in parallel at the signal input to the first electronic switch, connected in series to a second low-frequency amplifier, the direct input of which is connected nen with the output of the second electronic key, and the inverse input with the output of the fourth electronic key, the first bandpass filter, the second synchronous detector, the adder, the output of which is connected to the input of the DC amplifier, the second bandpass filter, the input of which is connected to the output of the first low-frequency amplifier, and the output is to the input of the first synchronous detector, the direct input of the first low-frequency amplifier connected to the output of the first electronic key, and the inverse input to the output of the third electronic key, and the second input adder and connected to the output of the first synchronous detector, as well as a first frequency divider into two, a second frequency divider into two, a logical element AND and a shift register, the four outputs of which are connected to the control inputs of four electronic keys, and the output of the pulse generator is connected to the clock input the shift register and the input of the first frequency divider into two, the second input of the logical element And is connected to the output of the first frequency divider into two, third and fourth band-pass filters, the inputs of which are connected they are with the first and second outputs of the shift register, and the outputs are with the second inputs of the first and second synchronous detectors, respectively.

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