WAVE-GUIDE BAND REJECTION FILTER HAVING A SHORT CIRCUITED COAXIAL TUNING SCREW

摘要

A band rejection filter for a microwave wave-guide formed of a wave-guide (11) and at least one short-circuited coaxial line. An inner conductor (17) and an outer conductor (19) are coaxial with the inner conductor (17) being a conducting rod extending a screw (12) and the outer conductor being at least in part a tapped hole (19) formed in the wall of the wave-guide (11). The screw (12) forms an adjustable short-circuit. The short-circuited coaxial line has a length slightly less than an odd multiple of a quarter wavelength corresponding to the central frequency of the frequency band to be rejected, so as to form an inductive susceptance. The end of the inner conductor (17) projects slightly into the wave-guide (11) to form a capacitive susceptance which is connected to the end of the coaxial line so as to form a resonator tuned to the central frequency of the band to be rejected.