RU1810985C - Dispersing delay line for surface acoustic waves - Google Patents

Abstract

The invention relates to acoustoelectronics and can be used to process signals, for example, to generate chirp signals or compress them. On the working surface of the sound duct 1 in two parallel acoustic channels 2 and 3 are placed input 4 and output 5 SAW converters. Both acoustic channels are blocked by a system of metallized strips 6 located parallel to the aperture of the transducers. The strips are arranged with a variable pitch, varying along the acoustic channels according to a predetermined law. The range of spatial triode intervals is given. 1 ill.

Description

The invention relates to acoustoelectronics and can be used to process signals, for example, to generate chirp signals or compress them.

The purpose of the invention is to reduce dimensions and improve manufacturability.

Achieving the goal is based on the following. An acoustic wave incident on metallized strips causes regenerated surface acoustic waves propagating over the surface of the sound to the duct on both sides of the strip system. The greatest regeneration effect occurs in areas of acoustic synchronism, i.e. where the pitch of the metallized strips is equal to half the length of the acoustic wave. That is, if metallic strips with a variable pitch of a broadband acoustic signal are incident on the system, the regeneration of different frequency components will occur in different parts of it. Regardless of the width of the acoustic stream incident on the strips, the regenerated acoustic waves will be reemitted in the aperture of the entire strip system. Moreover, if in some of its sections the length of the metallized strips is greater than the width of the acoustic beam, then the energy of the regenerated surfactant supplied to the output transducer will decrease in proportion to this length, which allows for the formation of an AFC for DLZ if necessary.

The drawing shows the design of the proposed DLZ on surfactants.

The dispersion delay line for the surfactant contains a sound pipe 1, on the working surface of which in two parallel acoustic channels 2 and 3 are located, input 4 and output 5 surfactant converters. Both acoustic channels 2 and 3 are blocked by a system of metallized strips 6 parallel to the aperture of transducers 4 and 5. The length of this system of strips in the direction of surfactant propagation is L The system of metallized strips is made with a variable step h, varying along the length of the grating according to this law in the interval values (Min va / 2fB - max va / 2fH), where va is the surfactant speed: fB and fH are the upper and lower frequencies of the DLZ passband, respectively. The law of changing the strips' pitch may be similar to the law of the position of reflective elements in known dispersion delay lines designed to generate a linear frequency-modulated signal. The figure shows the design of an SLC on a SAW for generating a LFM signal down, in which the strips move in the direction from converters range from Min va / 2fB to 1Max va / 2fH. The length of each of the metallized strips h is equal to the overlap of the acoustic channels 2 and 3, i.e. does not go beyond them.

To reduce the influence on the DLZ parameters of false signals reflected from the edges of sound duct 1 on part of sound duct 1

0 absorber applied 7.

In the signal conditioning mode, the proposed DLZ operates as follows. A short pulse is applied to the input converter 4, the spectrum of which 5 contains, in particular, all frequencies in the passband of the DL. The acoustic wave emitted by the input transducer 4 propagates along the working surface of the sound duct 1 in the first acoustic ka0 2 and reaches the system of metallized strips 6. The currents induced by the incident acoustic wave in the system of metallized strips 6 cause regenerated acoustic waves,

5 propagating in the first 2 and second 3 acoustic channels both towards the transducers 4 and 5, and in the opposite direction. The system of strips 6 is made with a variable step, varying from min.

0 to | Max, which corresponds to resonant frequencies from fB to. Thus, the regeneration of low-frequency components with respect to high-frequency components will occur with a temporary delay,

5 corresponding to the spatial diversity of the metallized strips with different pitch, and at the output transducer. 5, an LFM signal will be generated in the frequency band B fafn and with the dispersion delay time T L / va. In the direction from transducers 4 and 5, the regenerated waves will propagate without dispersion.

In order to form the apodization function5 determined by the given amplitude-frequency characteristic of the DLZ, the length of at least some metallized strips should be greater than the overlap of the acoustic channels.

0 in proportion to the length of the strip exceeding the channel overlap, the signal level reflected by the aperture of the output transducer increases. The law of changing the length of the strips in this case is chosen so that it is maximum along the edges of the strip system and decreases towards its middle to a value equal to the overlap, forming the amplitude-frequency characteristic of the DLZ with a blockage of the upper and lower frequencies with respect to the central frequency, those. Frequency response. in which the side lobes of the compressed signal will have a level significantly lower than that of unweighted structures. An advantage of this technical solution is the fact that in the apertures of the input and output converters, the metallized coating is uniform in the direction perpendicular to the direction of propagation of the surfactant.

Thus, the proposed technical solution makes it possible to transfer acoustic energy from the channel of the input transducer to the channel of the output transducer with a given signal dispersion in the DLZ design with reflective elements located perpendicular to the direction of propagation of acoustic waves without using a multi-strip directional coupler, which, while maintaining all the advantages such DLS simplifies their design by several tens of percent (depending on the dispersion time Delay) reduces the size of wire used sound-., Moreover metallised

strips can be made in a single technological cycle with input and output converters.

Claims (1)

Claims Dispersion delay line on surface acoustic waves, containing a sound duct, on the working surface of which are placed in two parallel acoustic channels input and output converters of surfactants and a system of reflectors overlapping both acoustic channels, including metallized strips located parallel to the aperture transducers, characterized in that, in order to reduce the dimensions and increase the manufacturability, the metallized strips of the reflector system are made with a variable spatial period P, varying along the acoustic channels according to a given law in the range of Max min, where 1max va / 2fH; min va / 2fB; va is the surfactant velocity; fH and fe - low and high frequencies bandwidth of the dispersion delay line.