Twin HF antenna feed system - has two vector outlet ducts with variable phasing device for each directional filter coupler

摘要

The microwave phase shift device is applied to an antenna feed system for two frequencies and two polarisation vectors for each frequency range, for maintaining circular polarisation (equal vectors at 90 deg. phase angle) even after phase distortion occurs through environmental factors such as heavy rain. To compensate for any change of the circular polarisation into a distorted (elliptical) polarisation, each polarisation vector duct is equipped with a field displacement wire with a common control for both wires. The two ducts (P1,P2) are placed side by side conveniently connecting to the directional coupling links (K1,K2). The phase adjustment action could be mechanised producing vector phase adjustment with a time constant of about one second.