An in-line waveguide-to-microstrip transition using radial-shaped probe

In this work, an in-line rectangular waveguide to microstrip transition using a radial shaped probe placed quarter-wavelength from a short-back is presented in Ka-band. The in-line structure does not need waveguide bending or cutting slots or holes on waveguide side wall, for applications using in-line input/output configuration. Compared with the design with various tapers shown above, the proposed structure is of a compact size. This fully printed structure, which is easy to fabricate, provides good performances within a wide bandwidth.