Wideband transition from coaxial line to half-mode substrate integrated waveguide

In this paper, a perpendicular transition from coaxial cable to Half-Mode Substrate Integrated Waveguide (HM-SIW) is proposed for wideband operation. The design places emphasis on the robustness and manufacturability of the transition, in particular with a reproducible realization of a matching capacitive gap. A prototype of back-to-back transitions with 64 mm length of HMSIW in-between is realized for operation in the frequency range of 10 GHz to 16 GHz. The return loss of the back-to-back transitions is measured to be close to 20 dB. A reasonable agreement between experimental and simulation results is achieved, validating the proposed transition geometry.