Multichannel Substrate Integrated Waveguide Diplexer Made of Dual-Mode Cavities and Split-Type Dual-Band Response

A multichannel diplexer using substrate integrated waveguide (SIW) technology is developed and presented for the first time using two SIW dual- mode cavities coupled with multiple single-mode cavities. In this work, a tri-channel duplexing system is studied. The 1st and 2nd channels of the diplexer are synthesized and designed as split-type dual-band response and constructed by TE101 modes in dual-mode cavities coupled with two TE101-mode bandstop cavities, while the 3rd channel is synthesized and designed as 3rd-order Chebyshev response and dominated by TE201 modes in the dual-mode cavities coupled with one TE101-mode bandpass cavity. The isolation in the 1st and 2nd channels is realized by cut-off characteristic of the single- mode cavity of the 3rd channel, while the isolation in the 3rd channel is achieved by arranging one output port at central position of one dual-mode cavity because of the weakest fields for TE201 mode. An experimental prototype centered at 10.051, 10.713, and 12.987 GHz is synthesized, designed, fabricated, and measured to demonstrate the collaborative design concept.