A full ka-band microstrip-to-waveguide transition using tapered CPS probe and V-antenna

A novel Ka-band microstrip-to-waveguide transition is presented in this paper. This transition is composed of a tapered coplanar strip (CPS) and a V-antenna which are inserted from E-plane center of a rectangular waveguide end. The mode transformation between waveguide and microstrip is achieved by electric field structural conversion in these two components. The impedance matching was also considered in the CPS design. The transition has characteristics of in-line structure, integration feasibility and compatibility in monolithic microwave integrated circuit (MMIC) technology. The Ka-band back-to-back transition fabricated on RT-duriod 5880 substrate demonstrates more than 85% bandwidth with overall measured insertion loss less than 1.5dB and return loss better than 15dB.