TUNEABLE FILTER

摘要

A tuneable filter is provided in whicha received signal in a first frequency rangeis translated to a signal of a higher frequency rangeby means of a switchable frequency oscillator signal, filtered in a narrow band filter and then down-converted, preferably to the first frequency range. The switchable frequency oscillator signals are generated by a synthesiser which operates by mixing oscillator signals of different frequencies, selected by means of fast- switching microwave switches, in order to generate the required range of oscillator signal frequencies.