Multiple-frequency autotrack feed for wideband communication systems

A travelling wave coupler autotracking system 10 controls the pointing of an antenna aboard an orbiting satellite by generating tracking signals covering a wideband frequency. The system 10 comprises a waveguide manifold 22 for exciting circular TE11 and TM01 modes covering a wideband frequency range, coupling arm waveguides 24, 26 for propagating signals having a phase velocity of TE10 mode that is the same as the phase velocity of TM01 mode, and couplers 30 for transforming microwave energy of the TM01 mode of the circularly polarized microwave signals into TE10 modes in the coupling waveguide. The system 10 can further comprise 180°-hybrid 20 for combining the TE10 modes in the coupling waveguides in phase and for generating one or more error signals at different frequencies.