Double-loop frequency selective surfaces for multi frequency division multiplexing in a dual reflector antenna
AssigneeThe United States of America as represented by the Administrator of the National Aeronautics and Space Administration
InventorTe-Kao Wu
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Abstract
A multireflector antenna utilizes a frequency-selective surface (FSS) in a subreflector to allow signals in two different RF bands to be selectively reflected back into a main reflector and to allow signals in other RF bands to be transmitted through it to the main reflector for primary focus transmission. A first approach requires only one FSS at the subreflector which may be an array of double-square-loop conductive elements. A second approach uses two FSS's at the subreflector which may be an array of either double-square-loop (DSL) or double-ring (DR). In the case of DR elements, they may be advantageously arranged in a triangular array instead of the rectangular array for the DSL elements.
Claims6
A dual-reflector system for frequency division multiplexing of four signals, each in a separate one of four radio-frequency bands comprising
- first and second radio-frequency signal reflectors facing each other, said second radio-frequency signal reflector having double-loop conductive elements arrayed for selective reflection of two signals in two separate radio-frequency bands,
- first and second feed systems, each feed system for transmission of a different selected set of two of said radio-frequency signals in separate radio-frequency bands,
- said second radio-frequency signal reflector having said arrayed double-loop conductive elements chosen for passing said two signals in different radio-frequency bands from said first feed system through said second radio-frequency signal reflector in a direction toward said first radio-frequency signal reflector, and for reflecting said two radio-frequency signals from said second feed system protruding through said first radio-frequency signal reflector back to said first radio-frequency signal reflector, said first radio-frequency signal reflector being chosen to reflect all of said sets of two radio-frequency signals from said first and second feed systems for transmission of said radio-frequency signals from said first feed system and said radio-frequency signal from said second feed system,
- wherein said arrayed double-loop conductive elements of said second radio-frequency signal reflector comprises a plurality of double-loop conductive elements on a dielectric sheet of known dielectric constant arranged to form at least one grid of elements, and dimensions of said double-loop conductive elements of said frequency-selective surface of said second radio-frequency signal reflector being chosen for passing said two signals in separate radio-frequency bands transmitted said first feed system and selective reflection of signals transmitted in separate radio-frequency bands by said second feed system.
Dependencies are inferred from the claim text.