Design of Waveguide Low Pass Filter using Rectangular Rings and Ridges

In this paper, a novel waveguide low pass filter for satellite communication is proposed. The proposed low pass filter is designed to obtain wideband characteristics without the interference of higher order modes, sufficient attenuation in the stop-band and small sized lightweight characteristics by evanescent-mode ridge structure. To improve return loss and rejection loss, rectangular ring is inserting around the ridges in the waveguide. Input and output ports of the low pass filter is designed by using the impedance step structure for the impedance matching of the filter. The proposed waveguide low pass filter is fabricated and then measured as return loss over 19.5 dB, insertion loss less than 1.41 dB at the pass-band of 7.25 ~ 8.4 GHz and rejection loss over 67.2 dB at the stop-band of 12.25 ~ 14.5 GHz.