Rotman Lenses With Ridged Waveguides In Q-Band

This paper provides a discussion on ridged waveguide Rotman lenses for satellite applications in Q-band. Two transition designs from the ridged waveguide feeding ports to the parallel plate waveguide lens cavity are compared. Whereas the longer transition provides slightly better return loss, the shorter transition reduces phase errors in the lens, translating into more accurate beam pointing and lower scan losses. S-parameters and normalised array factors are reported over the frequency range from 37.5 GHz to 42.5 GHz for both lenses, confirming the benefits of shorter transitions.