LOW-FREQUENCY WAVEGUIDE FILTER Russian patent published in 2016 - IPC H01P1/20 

FIELD: radio engineering.

SUBSTANCE: invention relates to UHF radio engineering and can be used for suppression of out of band and parasitic oscillations in channels of transceiving systems, including high power ones, as well as for coarse measuring frequency of microwave radiation. Waveguide LFF is rectangular waveguide of definite length with flanges with built-in into it on side of its wide walls opposite each other diaphragms with gap between them, at least portion of which (equal-height) is set of filter sections of low-resistance of capacitance nature, between which there are high-resistance of filter section formed by sections of rectangular waveguide between adjacent along wide wall of rectangular waveguide diaphragms and having inductive nature. Rest of diaphragms are arranged at inlet and outlet filter and serve for matching with input and output waveguides, which ensures minimization of losses in bandwidth filter. Cutoff frequency tuning LFF is realised by including in central part of two additional LFF diaphragms changing inductance of central section of filter, which enables to reconstruct cutoff frequency filter at value of up to 3 % of cutoff frequency and not degrading considerably losses in operating band of filter (≤3 dB). Technical result consists in development of simple in manufacturing of waveguide low frequency filter having cutoff frequency tuning and provides suppression of spurious signals at frequencies which exceed cutoff frequency not less than twice with minimum losses in bandwidth. Filter is intended for use in decimetre and centimetre wavelength ranges.

EFFECT: use of special manufacturing technology, for example, spark erosion machining, enables making LFF proposed design for use in millimetre wavelength range.

2 cl, 4 dwg