GB752142A - Improvements in or relating to band-pass filters for ultra-high frequencies - Google Patents

Abstract

752,142. Ultra-high-frequency filters. SOC. FRANCAISE RADIO-ELECTRIQUE. May 20, 1954 [May 20, 1953], No. 14909/54. Class 40 (8). A band-pass filter for ultra-high frequencies comprises at least two coupled resonators consisting of parallel conductive plates 3, 3a shortcircuited along at least one edge by a conductive element 4, each resonator having a conductive tuning member of circular section, e.g. 5, 5a. The resonators are designed by conformal transformation of the fields in an equivalent coaxial resonator. The construction of Fig. 4 comprises two such coupled resonators having additional conductive walls 12, 13 through which extend input and output probes 14, 15. The tuning members 5, 5a extend intothe space between the plates 3, 3a a distance equal to an odd number of quarter-wavelengths corresponding to the centre frequency of the pass band. They may be screw-threaded into the member 4. The width of the pass band is determined by the distance apart of the tuning members 5, 5a and by the position of an adjustable conductive strip 17. In a modification (Fig. 2, not shown) input and output loops extend through the member 4.