Tunable HF band-pass filter - has resonant cavities tuned by single control moving plate projecting through one wall of cavities

摘要

The tunable HF filter (up to 40 GHz) includes resonant cavities (1-4) of length equal to half the wavelength of the medium wave in the guide. They are coupled together by connections (13/14, 15/16, 17/18) and each cavity is corrected for mechanical imperfections by a metal insert (39-42) adjusted in the factory. On the side opposite to the metal inserts is a longitudinal window (30) extending the whole length of the cavities (1-4). A metal plate (31) is held in this window and is movable in or out of the cavities to tune the filter. The plate has notches cut so as to define four sections fitting into the four cavities.