A compact waveguide-to-half mode substrate integrated waveguide (HMSIW) transition using antisymmetric tapered probes is proposed. A good matching of field and impendence is achieved by the tapered probes. To verify the proposed transition, a back-to-back test module at Ka-band is fabricated and measured. It provides a return loss better than 14 dB and an insertion loss of 0.35 to 1 dB within a frequency range from 25 to 40 GHz. There is no need of intermediate transition for this design. The size of the proposed transition is reduced by approximately 83.8% as compared with the waveguide-to-HMSIW transition using antipodal fin-line.
