Design of a Compact Bandpass Filter with Capacity Loaded Ridged Waveguide

A K-Band bandpass filter, using a single ridge wave guide and capacity-loading posts, is presented in this article. It is based on transmission line and ridged wave guide theories. In contrast to the traditional evanescent-mode ridged wave guide filters, the width of both ridge and capacitor-loading post of the proposed new type of the ridged wave guide bandpass filter are the same. A filter is designed, simulated and fabricated at 22.3 GHz, demonstrating a fractional bandwidth of 42.2 percent, from 17.6 to 27 GHz, a VSWR less than 1.5 and an out-of-band rejection of-60 dB at 15 and 30 GHz, respectively. Based upon these good performances, the proposed ridged wave guide filter can be used in microwave and millimeter wave communication systems.