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