Abstract
SHS investigation development is considered from the geographical and historical viewpoint. 3 stages are described. Within Stage 1 the work was carried out in the Department of the Institute of Chemical Physics in Chernogolovka where the scientific discovery had been made. At Stage 2 the interest to SHS arose in different cities and towns of the former USSR. Within Stage 3 SHS entered the international scene. Now SHS processes and products are being studied in more than 50 countries.
Abstract
Low insertion loss and good temperature stability are the main requirements for
filters used in communication system front ends. These requirements severely limit the design
options for SAW filters that can be used in modern communication systems. It should be noted
that until recently SAW filters with a relative bandwidth of 1..10% and low losses, and most
demanded for communication systems, had low-temperature stability. This was due to the
temperature coefficients of waveguide material medium frequency of the SAW filters. Such
materials are strong piezoelectrics niobate and lithium tantalate.
Research aimed at improving the temperature stability of devices based on lithium niobate and
tantalate was started a long time ago. Still, only emerging new technologies have provided the
possibility of solving this problem for mass production conditions. Currently, the input circuits
of almost all mobile communication devices incorporate filters (duplexers) on SAW.
Keywords:
Acoustoelectric circuit, Bandwidth, Communication devices, Duplexer, Electromechanical coupling coefficient, Filter, Lithium niobate, Measurements, Surface acoustic wave, Transducer.
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Authors:Bentham Science Books