Magnetically tunable multisection bandpass filters in ferrite-loaded evanescent waveguide

A description is given of a novel type of bandpass filter constructed in ferrite-loaded waveguide and using the evanescent-mode principle of operation. These filters may be multisection, and their operating band of frequencies may be tuned by a single-knob control of the d.c. magnetic field on the ferrite. Performance of a 3-section bandpass filter is given.