Compact SIW filters with transmission zeros: A review and current trends

Abstract

This paper presents a review of the recent advances in the field of substrate integrated waveguide (SIW) filters, with particular emphasis on the techniques adopted to increase the out-of-band rejection of the filters and on the miniaturization strategies. After an overview of classical approaches to introduce transmission zeros in SIW filters, a number of recently introduced techniques are presented. In particular, the use of specially implemented extracted-poles topologies and of pre-filters is described, discussed, and compared. For each of these techniques, numerical and experimental results are reported for validation.

Broadband and compact folded substrate integrated waveguide phase shifter and its application to 180° directional coupler

“…For size reduction, several SIW-derived transmission lines (TLs), including the half-mode SIW (HMSIW) [2], ridge SIW [3], and folded SIW (FSIW) [4,5], have also been proposed. Based on these structures, a variety of microwave devices, such as bandpass filters [6][7][8], directional couplers [9, 10], and phase shifters [11][12][13][14][15][16][17][18], have been proposed. To feature as a good phase shifter, it has to show a wide bandwidth, a good impedance matching, a low insertion loss, a compact size, and an equal-length structure.…”