Design of Ortho-Mode Junction with Waffle-Iron Filters for K/Ka Band Shared Aperture Antennas

The shared aperture reflector antenna used for satellite communication requires the downlink to operate at the K and Ka frequency bands, with RHCP, and the uplink to operate at the Ka frequency band, with LHCP. The feed chain is a key component for achieving its performance. The OMJ (Ortho-Mode Junction) with 4 -arm waffle-iron filters described in this article is the core component of the feed chain. It is a design challenge to balance the performance of low-frequency signal coupling, high frequency signal insertion loss, low-pass filtering, and high-order mode suppression, especially when the K-band and Ka-band are close to each other. By using structural parameter design and optimization, waveguide mode control, and full-wave simulation analysis, the above difficult problem has been solved. The simulation results show that the performance meets the application requirements of the multi-frequency band shared aperture antenna.