A Circularly Polarized Single-Frequency Multimode Helical Beam Antenna

An antenna based on a TM coaxial resonant cavity with radiating annular slots on one face and excited by multiple open-ended TE mode coaxial resonators on the opposite face is shown to simultaneously radiate the corresponding circularly polarized helical beams modes over a single-frequency band with good isolation between modes. S-parameters are calculated for a transmit-receive configuration with the antennas separated by 10 wavelengths. The initial antenna concept was developed interactively using the conformal finite difference time domain method with a Titan-XP GPU.