SU684720A1 - Low-temperature acoustic microwave delay line - Google Patents

Description

The invention relates to microwave technology, namely, low-temperature acoustic microwave delay lines based on the use of an electro-acoustic converter of a microwave electromagnetic signal into an acoustic signal, and can be used in devices and laboratory installations that require long delays of microwave electromagnetic signals, for example, in studying processes associated with with the propagation of microwave acoustic waves in solids.

A device is known in which loop transformers 1 are used to safeguard the resistances of piezoelectric transducers with a transmission line resistance.

The disadvantage of the device is the low efficiency of mutual conversion of electromagnetic and acoustic waves.

A known low-temperature acoustic microwave delay line containing a transmission line, a matching device, and a piezoelectric device connected to the cryostat.

a converter and a single-crystal suction pipe 2 connected to it.

However, an increase in conversion efficiency is achieved by increasing the quality factor of the matching device, in this case a toroidal resonator, which narrows the operating frequency band of the low-temperature acoustic microwave delay line.

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The purpose of the invention is to increase the conversion efficiency while expanding the working frequency band.

This is achieved by the fact that p. low temperature acoustic microwave line

5 delays containing a transmission device placed in a cryostat, an associated matching device, a piezoelectric transducer and a single-crystal sound conductor connected to it, the matching device is made in the form of a short-circuited four-wave U-shaped waveguide, to the protrusion of which is Φ f4 -from the fixed end of the connection is: a half-wave segment coaxial; 1 line, loaded: nd on the piezoelectric transducer. Conductors of a half-wave coaxial segment

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the lines consist of metal, concentrically located cones, the contact surfaces of which are located in the same plane and processed with optical precision

1a shows a low-temperature acoustic microwave delay line, a slit,

 The temperature of the acoustic 1 UHF delay line contains a cryostat 1 filled with a liquefied gas cooler. In the cryostat 1, the transmission line 2 is placed, which is made, for example, in the form of a neisilbert flat waveguide. Such a waveguide can significantly reduce the heating of liquefied gas due to heat from the environment. Line 2 transmission to the cryostat 1 is connected to the matching device. It is a shorted quarter-wave segment of the U-shaped waveguide 3, which is cocTtJKOsaH directly with a rectangular waveguide of the transmission line 2. A conductor 4 is connected to the protrusion of the U-shaped waveguide 3 at the A / 4 distance from the short-circuited end. The conductor 4 is made in the form of a metal cone. It forms with the upper edge 5 of the U-shaped waveguide 3, in which there is a conical hole, a coaxial line. Hole and conductor 4 are located concentric. The inner cavity of the conical hole in the lid 5 of the U-shaped waveguide 3 and the conductor 4 are a length of coaxial line b / D. The plane of the cover 5 of the U-shaped waveguide 3 and the conductor 4 are located in the same plane and processed with optical precision. They are contact electrodes. A piezoelectric transducer 6 is connected to these electrodes and is connected to a single-crystal evukuy conduit 7. The piezoelectric transducer 6 is a thin piezoelectric zinc oxide film deposited by vacuum sputtering on one of the plane-parallel ends of the sound duct 7. The euing conduit 7 is made of a single crystal in the form of a cylinder or a template. with plane-parallel face edges. The plane of the ends is processed with optical precision. Transmission line 2, matching device, piezoelectric transducer 6 and suction line 7 are sealed against the environment to prevent frosting.

The low-temperature acoustic microwave delay line operates as follows.

Electromagnetic microwave signal through transmission line 2 is supplied to

to the device. On the contact electrodes of the matching device 1, which are Kptjima 5 U-shaped volg-water supply 3 and conductor 4, the electrical component of the electromagnetic field is separated. A piezoelectric transducer 6 mounted on contact electrodes converts an e-tektromagitnuyu wave into an acoustic one. The acoustic wave propagating in the conduit 7 from the end with the piezoelectric transducer 6 is reflected from the free end of the sound conductor 7 and again gets to the piezoelectric transducer (forming the body 6). This reduces the acoustic power of the acoustic wave to the propagation time in the acoustic duct 7 is cooled in the cryostat 1. After mutual conversion of the electromagnetic and acoustic waves from the matching device into the transmission line 2, the post The signal delayed by the acoustic wave propagation time in the sound duct 7 falls. Experimental testing of the low-temperature acoustic microwave delay line was carried out while cooling the sound duct to the liquid nitrogen temperature (T-P K) in a three-centimeter radio wave range. The optical conductor was made of a single ruby crystal. The piezoelectric converter served zinc oxide film. The frequency band of the low-temperature acoustic microwave delay line is more when the mutual conversion loss is less than 30 dB, i.e. less than 15 db per conversion. The departure of the operating frequency during cooling from room temperature to the temperature of liquid nitrogen was less than 1%, and the efficiency of the conversion, with an accuracy of measurement error (± 0.2%), did not change.

Claims (2)

The low-temperature acoustic microwave delay line provides effective conversion of microwave electromagnetic and acoustic waves with a significant expansion of the working frequency band. Compared with the known low-temperature acoustic microwave delay line, the conversion efficiency is increased from 20-25 dB to 15 dB. The operating frequency band was 5% instead of 0.07%. The departure of the operating frequency during cooling was less than 1%. With such a narrow range of operating frequencies, there is no need for mechanical adjustment. Measurement accuracy is improved as the change in conversion efficiency is less than 0.2 dB. The design reliability increases. . The KOiiaKTHtJC -electrodes, made in such a way, allow testing of paj .. H4Hi-je samples of single-crystal sound guides, as well as exploring their different areas in order to identify areas with a minimum number of defects. The change in the surface area of the central electrode, KOTOPIJM is the tip of the pin, in the contact plane allows the excitation area of the piezoelectric transducer to change the acoustic wave in the acoustic duct. This, in turn, changes the transverse dimensions of the sound beam in the sound (from several thousand mm to several mm). Invention Low-MW Acoustic Acoustic Line containing a transmission device associated with it, a piezoelectric transducer matching the cryostat and a single-crystal sound wire connected to it, characterized in that, in order to increase the conversion efficiency during the expansion of the working frequency band, the device is designed as a shorted about a quarter-wave segment of a Shaped waveguide, to a ledge of which at a distance of A / 4 length from the short-circuited end is connected a half-wave segment of a coaxial line, loaded onto a piezoelectric transducer, with the conductors of a half-wave segment of a coaxial line with x; the surfaces of which are located in the same plane and processed with optical precision. Sources of information, Ifin Je are taken into account when examining 1.IEEE Trons on Ultrasonics Engin YI, p.27, 1963. 2. To produce the Academy of Sciences of the USSR, 1971, 5, vol. 35, p. 948 (prototype).