Different inline transitions between rectangular wave guides and planar waveguides

Easy manageable, stable and low-loss transitions between rectangular waveguide and planar transmission lines for the use in X-band communications are shown. Parallel plate lines are brought specially into focus, because feeding of TEM horn antennas, which are excellent candidates for wideband double polarized electronically steerable antenna arrays, can be done effectively by this transmission line type. To realize high Q demanding components like filters or diplexers, rectangular waveguides are still a very good and common choice. Therefore field coupled transitions from rectangular wave guide to parallel plate transmission line and from parallel plate to parallel plate lines are analyzed by full wave analysis and measurements. The presented transitions show insertion losses per transition about 0.5 dB and efficiency factors better than -0.25 dB which makes them well suitable for X-band communications.