A full Ka-band microstrip-to-waveguide transition using side-inserted magnetic coupling semicircular ring

A novel microstrip-to-waveguide transition utilizing a semicircular microstrip ring is presented. This transition is based on the side-inserted structure of magnetic field excitation in a rectangular waveguide. It has filled in blank of structures with which a rectangular waveguide can be excited from its narrow wall. It is also compact, and has advantages of full Ka-band availability, low insertion loss, structural flexibility and easy fabrication. Field coupling, impedance matching and compensation structures are included in this design. Structural characteristics of this transition and design of its individual components are analyzed in detail. Simulation and measurement of this transition are also discussed. The Ka-band back-to-back transition with RT-duriod 5880 substrate demonstrates the whole bandwidth with overall insertion loss between 0.95dB and 1.94dB, and return loss better than 11dB, respectively.