Rapid-switching rotatable waveguide polarizer feed assembly for maintaining satellite communications links during spot beam transition

A radio-frequency feed system for selective polarization reversal, comprising:

• a fixed RF section comprising a transmit signal path and a receive signal path;
• a frequency-selective network coupled to the fixed RF section and configured to combine or separate the transmit signal path and the receive signal path at a common waveguide interface;
• a stationary waveguide coupling structure coupled to the common waveguide interface;
• a rotatable waveguide polarizer structure coupled to the stationary waveguide coupling structure and comprising an internal polarization-transforming structure positioned in an antenna-side waveguide passage;
• and
• a rotary waveguide interface between the stationary waveguide coupling structure and the rotatable waveguide polarizer structure, the rotary waveguide interface comprising a choke-defined RF leakage suppression region that permits mechanical rotation of the rotatable waveguide polarizer structure relative to the stationary waveguide coupling structure,
• wherein mechanical rotation of the rotatable waveguide polarizer structure selectively reverses handedness between opposite circular polarizations communicated through the antenna-side waveguide passage,
• wherein the rotatable waveguide polarizer structure comprises a first internal transfer passage and a second internal transfer passage each extending between the antenna-side waveguide passage and a respective interface opening of the rotatable waveguide polarizer structure, the interface openings being selectively brought into angular alignment with the stationary waveguide coupling structure at discrete indexed rotational positions of the rotatable waveguide polarizer structure to establish corresponding discrete polarization states.

A method of operating a polarization-selective waveguide feed assembly, comprising:

• providing a fixed RF section including a transmit signal path and a receive signal path;
• combining or separating the transmit signal path and the receive signal path through a frequency-selective network at a common waveguide interface;
• communicating RF energy between the common waveguide interface and a rotatable waveguide body through a stationary waveguide structure;
• passing the RF energy through an axial waveguide passage of the rotatable waveguide body containing a polarization-transforming structure;
• and
• rotating the rotatable waveguide body relative to the stationary waveguide structure to change an angular orientation of the polarization-transforming structure and thereby change a polarization state communicated through the axial waveguide passage without switching the RF energy through a separate waveguide switching device,
• suppressing RF leakage at a rotary interface between the rotatable waveguide body and the stationary waveguide structure using a choke structure carried by the rotatable waveguide body, the choke structure maintaining RF integrity across a physical gap at the rotary interface while permitting the rotatable waveguide body to rotate to a selected discrete angular position at which internal transfer passages of the rotatable waveguide body are brought into alignment with corresponding waveguide channels of the stationary waveguide structure to establish the changed polarization state.