A Compact Bandpass Filter Based on HMSIW with Broad Upper Stopband

Abstract

In this work, the periodic mushroom structures are loaded in the HMSIW. As a result, the size of SIW cut-mode cavity is reduced significantly; and a wide electromagnetic bandgap appears in a certain frequency band. Based on this structure, a compact HMSIW bandpass filter with broad upper stopband is designed. The filter centered at 6.92GHz exhibits an ultrawide upper stopband up to 37.72 GHz with a rejection level of 20 dB. The area of the filter is only $0.147\lambda_{g}^{2}$, where $\lambda_{g}$ is the guided wavelength at the center frequency in the dielectric. The theoretical analysis and design method are given in details in this paper: