Frequency multiplexing excitation network for ultra-wideband coaxial waveguide feeds

A new technique for exciting the TE₁₁ mode in a number of concentric coaxial waveguides is described. The excitation network is log-periodic and is designed to integrate a frequency multiplexing structure together with suppression of higher order modes (TE₂₁ and TE₃₁). The excitation network enables the implementation of very wide band nested coaxial feeds for reflector antennas where multiple waveguides are fed from a common input port. An excitation network providing continuous coverage over a 1-8 GHz frequency range was built and tested in a three-band coaxial waveguide feed.