SU368709A1 - CARRIER CONVERTER FREQUENCY MODULATED VIBRATIONS - Google Patents

Description

one

The invention relates to the field of radio engineering and can be used in radio receiving and radio transmitting equipment, as well as in automation and telemechanics systems.

Carrier transducers of modulated oscillations are known, containing two piezoelectric plates, one of which is covered with solid electrodes on both sides and polarized in opposite directions in thickness, the other plate polarized in one direction in thickness and covered with a flat electrode on one side, and the plates acoustically connected to each other over a surface covered with a flat electrode. These converters have insufficient service life, low reliability and large dimensions.

The aim of the invention is to eliminate these drawbacks.

In the proposed converter, the second plate on the other hand has separated input and output electrodes, between which there is a narrow metallized strip connected to a solid electrode.

FIG. 1 shows the structure of the described converter; in fig. 2 is a converter connection circuit; in fig. 3 - his performance.

The modulated oscillation carrier transducer is designed as a monolithic structure consisting of two acoustically coupled piezoelectric plates. The piezoelectric plate / polarized in thickness in opposite directions and covered with electrodes 2 and 5. Electrode 3 is located on the surface along which the acoustic coupling of the plates takes place. Piezoelectric plate 4 is polarized in thickness in one direction, and input 5 and output 6 electrodes are located on its surface. In order to eliminate the passage of the interference signal directly from

the entrance to the exit through the interelectrode capacitance between the electrodes 5 and there is a narrow metallized strip 7 connected to a solid electrode.

Carrier Converter Operation

modulated oscillations are based on the use of the dependence of the transmission coefficient on the voltage of the piezoelectric element on the value of the additionally introduced acoustic energy, i.e., on the magnitude of the electrical pumping signal of the resonance frequency supplied to the piezoelectric plates. The specific polarization of the piezoelectric plates and the arrangement of the electrodes make it possible to efficiently introduce additional acoustic energy and, at the same time, do not allow the pump signal to pass to the output of the converter. When applying to the input of an electric signal converter, whose frequency is equal to the main resonant frequency of the piezoelectric plates, the output will be a signal of the same frequency. Voltage transfer ratio equal to Do remains constant. When an electric signal is applied to the input of the converter, the frequency of which coincides with one of the minor resonant frequencies, the voltage transfer coefficient / C varies (Fig. 3, a). Thus, if an amplitude-modulated signal is fed to the converter input with a carrier frequency equal to the second mode of oscillation in length, the transmission coefficient for the voltage K.U will change according to the law of variation of the pump signal amplitude. As a result, the output of the converter produces a signal modulated in amplitude according to the same law as the pump signal, but its carrier frequency equals the fundamental resonant frequency of the piezoelectric plates. The dependence of the transmission coefficient on voltage / Cu on the frequency of the pump signal (Fig. 3, b) allows it to be used for

converting frequency-modulated oscillations into amplitude-modulated oscillations with a carrier frequency equal to the fundamental resonant frequency of the piezoelectric plates.

Subject invention

A carrier-frequency converter of modulated oscillations containing two piezoelectric plates, one of which is covered with solid electrodes on both sides and polarized in thickness in opposite directions, the other plate polarized in thickness in one direction

and is covered with a solid electrode on one side, the plates being acoustically connected to each other along a surface covered with a solid electrode, characterized in that, in order to increase the service life,

reliability, as well as downsizing, the plate is covered with a solid electrode on the one hand, on the other hand it has separated input and output electrodes, between which there is a narrow metallized strip connected to a solid electrode.