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US 6,300,894 B1Granted
Antenna having electrically controllable radar cross-section
AssigneeHarris Corporation
InventorsMichael J. Lynch, Charles M. Newton, George M. Walley
Life of this patent
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AssigneeHarris Corporation
InventorsMichael J. Lynch, Charles M. Newton, George M. Walley
Estimating the term…
An RF interface is configured as a laminate structure having a core layer of a ferromagnetic ceramic material, such as barium strontium titanate, whose permitivity is electrically controllable to modify the behavior of impinging electromagnetic energy, as one of minimally attenuated transmission, maximally attenuated absorption, and highly unattenuated reflection. Opposite surfaces of the ceramic core are coated with an electrically lossy material, such as indium tin oxide, to which a differential DC voltage is applied, and thereby imparting a DC electric field to the core layer. For an antenna application, during transmit/receive mode, the differential voltage has a magnitude that renders the laminate's core highly conductive, and thereby reflective to the RF wavelength being sourced from or received by an associated feed horn. During other times, the differential voltage renders the laminate effectively transparent to RF wavelengths in a prescribed band of interest (e.g., a search radar emanating from a threat platform, such as an aircraft).
An RF energy interface comprising a laminate structure of a core layer of ferromagnetic ceramic material, having a permitivity that is electrically controllable to modify the behavior of impinging electromagnetic energy, opposite surfaces of said ceramic core having an electrically conductive material thereon, and a differential DC voltage applicator coupled thereto so as to impart a differential voltage to said core layer, said applicator being operative, during transmit/receive mode of an antenna application to set said differential voltage at a first value that renders said laminate structure reflective to RF energy, and during other times, to set said differential voltage at a second value that renders said laminate structure effectively transparent to said RF energy, and during transmit/receive mode of a radome application, being operative to set said differential voltage at a third value that renders said laminate effectively transparent to RF energy, and during other times, to set said differential voltage at a fourth value that is effective to render said laminate effectively absorbent of said RF energy.
A radome for an antenna housed therein comprising a multi-laminate structure of plural layers of ferromagnetic ceramic material, each having a permitivity that is electrically controllable to modify the behavior of impinging electromagnetic energy, opposite surfaces of said layers of ceramic material having electrically conductive material thereon, and a differential DC voltage applicator coupled thereto so as to impart differential DC voltages across said layers, said applicator being operative, during transmit/receive mode of said antenna to set said differential voltages at a first value that renders said multi-laminate structure reflective to RF energy, and during other times, to set said differential voltages at a second value that renders said multi-laminate structure effectively transparent to said RF energy.
An apparatus for controllably interfacing radio waves incident upon a prescribed spatial region comprising:
A method for controllably interfacing radio waves incident upon a prescribed spatial region comprising the steps of:
Dependencies are inferred from the claim text.