Design of U-band Bandpass Filter Based on Loaded Dielectric Slot Gap Waveguide Technique

Abstract

In this paper, a U-band bandpass filter based on dielectric loaded slot gap waveguide is designed. A mushroom-type electromagnetic band-gap structure substrate is used to integrate the slot-gap waveguide. And the dispersive mode method and waveguide transmission method are applied to numerically analyze the mushroom-type band-gap structure. And the mushroom-type band-gap structure is analyzed by using two methods of frequency band-gap numerical analysis. The resonator is designed to achieve dielectric loading by retaining the slot gap waveguide over the dielectric substrate. And it makes the height of the air gap in the middle of the resonator substrate reduced. The result is a filter with a smaller size, narrower bandwidth, and high out-of-band rejection. The physical test results show that the center frequency of the filter is 50 GHz, the bandwidth is 500 MHz, and the relative bandwidth is 1%. And the in-band insertion loss of the filter is less than 3 dB and a return loss is less than −15 dB.