RU2337370C1 - Method and device for measurement of electromagnetic field intensity - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: detect the signal accepted by the aerial SHF detector, refer on the balancing modulator and make its disbalance, receive the changed potential proportional to the accepted signal, filter the concentrated selectivity with a filter, strengthen the potential amplifier, detect again and register the indicator of magneto-electric system of a direct current. The device contains quartz generator (heterodyne), resonant reception aerial, first SHF detector, balancing modulator, frequency filter of the concentrated selectivity, amplifier, second detector and indicator.

EFFECT: sensitivity rising, expansion of range of measurement and power consumption decrease

2 cl, 2 dwg

Description

The invention relates to electronic equipment, more specifically to measuring instruments that measure the intensity of the electromagnetic field in the radio bands.

The methods and instruments for measuring the electromagnetic field in the microwave range, referred to as methods for measuring the power of microwave oscillations, are well known:

1. Measurement of the power of the generator of electromagnetic waves by absorbing type wattmeters.

In this case, the measured power is completely dissipated on the measuring equivalent of the load, followed by the measurement of the power of the thermal process. Since the load must completely absorb the measured power, the use of the device is possible only with the device turned off.

2. Measurement of electrical power released in the load, the impedance of which can be arbitrary. In this case, a special device is switched on between the generator and the load, converting only a small part of the energy transmitted through the line into another head start and not violating the process of its transmission.

3. Power measurement using resistive thermosensitive elements by the method of measuring low powers, on which industrial wattmeters are built, is a method of measuring the resistance of a resistive thermosensitive element (thermistor) when electromagnetic energy is scattered on it. As thermistors, bolometers are used, the resistance of which increases with increasing temperature and thermistors whose resistance decreases with increasing temperature.

Thermistors have an advantage over bolometers in higher sensitivity and greater resistance to overloads.

The measurement of the resistance of a thermistor during the dissipation of electromagnetic energy in it is measured using bridge circuits.

Unbalanced bridges are used for power meters according to the type of direct-acting devices; balanced - in wattmeters, based on comparison methods. The disadvantages of these bridges are low measurement accuracy.

4. Power measurement with thermocouples.

The measurement method is based on recording the value of thermopower that occurs when a thermocouple is heated with microwave energy. In the microwave range, thermocouples are used in the form of thin metal films deposited on a dielectric substrate. The disadvantage is the limited upper level of the dynamic range, instability to overloads, limiting the allowable value of the average power when measuring pulse signals.

5. The calorimetric method for measuring power is based on the conversion of electric energy from electromagnetic waves absorbed by a matched load into heat. The calorimetric meter consists of two parts: the absorbing load and the temperature meter. The power absorbed in a water load with running water is determined by the temperature difference.

The disadvantage is rather complicated, bulky and not mobile, high error due to indirect measurements.

6. Methods of measuring transmitted power.

The transmitted power of the electromagnetic wave can be measured by wattmeters with directional couplers and devices with power meters on Hall converters with an absorbing wall.

6.1. In waveguide power meters, incident and reflected waves of microwave energy are separated by a waveguide directional coupler. An incident wave propagates along the main wave line from the generator to the load and reflected from the load to the generator. The auxiliary wave line operates in matching mode. The incident wave is fed to the wattmeter, and the power of the reflected wave is dissipated at the matched load. The disadvantage is a very complex block diagram and configuration.

6.2. Power measurement by Hall converters.

The semiconductor Hall transducers (sensors), through which a current excited by an electric field with a voltage E flows, are placed in a magnetic field with a voltage N, then a potential difference arises between points lying on a straight line perpendicular to the directions of the flowing current I and the magnetic field. To measure this power, a semiconductor wafer — a Hall wafer — is placed in a waveguide. The disadvantage is the practical implementation of the Hall effect wattmeters - a rather difficult task due to many factors used in the measurement.

7. Wattmeters based on the effect of “hot” current carriers.

In the theory of semiconductors, this effect is called the heating of charge carriers. The inhomogeneous heating of the semiconductor wafer excites the flow of charge carriers from the hot to the cold region, with the current I = 0. When “heating up” is carried out by the energy of the microwave field, the EMF value can be used to judge the microwave power passing through the plate. Wattmeters based on the “warming up” of charge carriers allow direct measurement of pulse power with pulse durations of up to 0.1 μs. The main unit in the device is a receiving transducer with a semiconductor element and a measuring device with digital readout.

These measurement methods are not able to pick up radiation signals with modulation of a pulsed nature.

Well-known devices are EMR-200, EMR-300, EMR-20/30 type electromagnetic radiation meters. These instruments are designed to measure in the near reception zone (directly near the radiation source) and have a lower sensitivity than the invention. The digital scale of these devices does not provide registration of emissions with modulation of the pulse form (PCM) of microwave communication in the range of 900-1800 MHz.

Similar disadvantages are also encountered in devices of the type P3-31, P3-40, P3-41, P3-18, P3-19, P3-20, the design of which uses a set of antenna converters whose operation is based on heating thin resistive films when exposed to them with electromagnetic radiation (continuous generation mode - NG) and registration of heating with a thin-film thermocouple element, as well as short dipoles and loop antennas combined with a microprocessor device.

The closest analogue (prototype) is the P4-4 interference meter (IP-25), which has high sensitivity, but only in the range up to 20 MHz, and has a large power consumption.

The aim of the present invention is to provide a method and device having high measurement sensitivity both in the near and in the far receiving zone in a wide frequency range, including microwave, and reducing power consumption.

The goal is achieved by changing the basic radio circuit for the conversion of electromagnetic radiation signals in the microwave range using a quartz oscillator (local oscillator), a balanced modulator, a concentrated selectivity filter and resonant receiving antennas.

Description of the method of the invention for measuring electromagnetic field strength.

Shown in figure 1

Detachably mounted on the housing 1, the antenna 2 receives the signal 11 in the form of electromagnetic radiation in the microwave range. The first microwave detector 3, the signal 11 is detected in the signal 12. The balance modulator 4 is powered by a voltage of 13 crystal oscillator (local oscillator) 5.

Balanced modulator 4 voltage 13 of the crystal oscillator (local oscillator) 5 is suppressed in voltage 14.

When the signal 12 is supplied to the balanced modulator 4, it is unbalanced and the output of the latter receives an altered voltage 15 in proportion to the input signal 12.

The changed voltage 15 is filtered by a frequency filter of concentrated selectivity 6, the main harmonic 16 is isolated, then it is amplified by a voltage amplifier 7, detected by a second detector 8 and recorded by an indicator 9 of the DC magnetoelectric system.

Power supply is carried out by a direct current source 10 with a voltage of 9-12 volts with a current consumption of 10-12 mA.

Description of the device for implementing the method for measuring electromagnetic field strength

Shown in figure 2

The device has a housing 1, an antenna 2, a microwave detector 3, a balanced modulator 4, a crystal oscillator (local oscillator) 5, a concentrated selectivity filter 6, a detector 8, an indicator of the magnetoelectric system of direct current 9, and a constant power supply are installed between the balanced modulator 4 and amplifier 7 current 10.

Description of the method and device for measuring electromagnetic field strength

Shown in figure 1

Power is supplied from a source 10 with a voltage of 9 V, while a crystal oscillator (local oscillator) 5 generates its own self-oscillation with a frequency that depends on the characteristics of the crystal.

The balance modulator is powered by a voltage of 13 quartz oscillator (local oscillator) 5.

Adjust the balanced modulator 4 with a variable (tuned) resistance and suppress voltage 13 to voltage 14.

The signal 12 is supplied to the balanced modulator 4 and it is unbalanced, while the suppressed voltage 14 is changed into voltage 15 in proportion to the input signal 12.

The changed voltage 15 is filtered by a frequency filter of concentrated selectivity 6, the main harmonic 16 is isolated, then it is amplified by a voltage amplifier 7, detected by a second detector 8 and recorded by an indicator 9 of the DC magnetoelectric system.

Sources of irformation

1. A.V. Trubitsin. Electromagnetic fields and life safety. Moscow, 1996

2. Catalog. Devices for measuring and controlling magnetic and electric fields and electromagnetic radiation. Moscow, MGP VNTORES im. A.S. Popova, 1992

3. N.S. Livshits, B.E. Teleshevsky. Radio engineering measurements. Moscow, "Higher School", 1968

4. I.P. Zherebtsov. Introduction to decimeter and centimeter wave technique. "Energy" Leningrad, 1976

5. O.L. Muravyov. Radio transmitting devices. Moscow, Svyaz, 1976

6. Electroradio measurements. Edited by Prof. A.S.Sigov, Ph.D. Moscow, "Forum - Infra - M", 2004

7. Yu.D. Belik, V.K. Bityukov, V.I. Nefedov, A.M. Cheshev. Fundamentals of radio electronics and communications. Moscow, 2004

8. Web. information.

Claims (2)

1. A method for measuring the intensity of an electromagnetic field with a frequency of 300-3000 MHz, including receiving signals by an antenna, converting it into thermal or other type of energy, followed by processing by a measurement system, characterized in that, in order to increase the sensitivity in the near and far reception zones, reduce power consumption, the received signal is detected by a microwave detector, sent to a balanced modulator and unbalanced, receive an altered voltage proportional to the received signal, filtered by a co-filter edotochennoy selectivity, increase the voltage booster, a second indicator is detected and recorded magnetically DC electrical system. 2. Device, device for measuring electromagnetic field strength, comprising an antenna mounted on a housing in which radio elements are mounted electrically connected to a radio circuit, characterized in that, in order to expand the measurement range (reception), including the microwave range, in the near and in far reception zones (measurements), increasing sensitivity, reducing power consumption, the device (receiver-meter) is made using the first microwave detector to detect the signal from the antenna, balanced a modulator for changing the voltage coming from a quartz oscillator (local oscillator), a frequency filter of concentrated selectivity to isolate the fundamental harmonic and suppressing side harmonics of a quartz oscillator (local oscillator), a frequency filter is installed between the balanced modulator and the amplifier, on which the changed voltage is amplified, after which the second detector it is detected and registered by an indicator of the magnetoelectric system, the power supply of the elements is carried out from a direct current source.

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