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.