Abstract - The results of investigation and practical application of "low-loss" filters on surface acoustic waves (SAW) in ethereal collective television systems in city conditions are given. Use of the circuit of channel amplifiers in which frequency selectivity is carried out by the high-frequency SAW- filters included on an input and an output of the amplifier is analysed.
Now in Russia the rough growth of information technologies is observed. The important place in this process occupies the decision of a problem of multichannel television reception in cities, settlements and individual structures, there the qualitative reception and distribution in a collective network of ten - fifteen television programs probably at performance of the following conditions:
The given work is devoted to the solution of a problem of a filtration and equalization of television channels (TVC) by means of the high-frequency channel SAW-filters being a the basic part of channel amplifiers (CA).
In this work the selectivity of CA is achieved by high-frequency low-loss SAW-filters, which are established on an input and an output of each amplifier. The block-diagram of construction is shown on fig.1
The requirements to the electrical characteristics of such SAW-filters following [1]:
The major problem by development of these filters was the finding of the compromise [2] between such parameters as insertion attenuation, selectivity and width of a passband. The relative width of a passband should vary over a wide range for various TVC thus selectivity on next TVC must be maximal.
For realization of required parameters three types of designs are investigated: longitudinally - coupled resonator filters (LCRF), SAW-filters exploiting U-shaped multistrip couplers and SAW resonator filters exploiting reversive multistrip couplers. The choice is made for the benefit of structure of the first type. The design of the given type of SAW-filter is shown on fig. 2 and experimental characteristics - on fig. 3 and 4 (8-th and 29-th TVC accordingly).
In work the way of a filtration and equalization of signals of television broadcasting channels is investigated by means of high-frequency channel SAW-filters.