Near field scattering antenna casing for arbitrary radiation pattern systhesis
AssigneeThe Government of the United States of America, as represented by the Secretary of the Navy
InventorsBrian O. Raeker, Scott M. Rudolph
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Abstract
Systems and methods are disclosed for creating antenna casings, such as radomes, that can reshape the distribution of electromagnetic energy emitted by an antenna into an arbitrarily defined pattern. Embodiments of the present disclosure include antenna casings with cylindrical patterns with only azimuthal variation and antenna casings with spherical patterns having both azimuthal and elevation variations, each accomplished with an antenna casing of a fixed radial distance in the given coordinate system (either cylindrical or spherical). Antenna casings provided by embodiments of the present disclosure can alter the source radiation pattern into any desired radiation pattern at any distance.
Claims20
A method for designing an antenna casing for an antenna based on a desired electric field for radiation, the method comprising:
- determining a desired scattered electric field to be created by the antenna casing, wherein the desired scattered field is equal to a desired incident electric field to be generated by the antenna minus the desired electric field;
- determining, based on the determined desired scattered electric field, a plurality of desired currents for unit cells of the antenna casing;
- discretizing, based on a geometry of the antenna casing and the plurality of desired currents, the determined desired scattered electric field into a plurality of component electric fields to be generated by the unit cells;
- determining, based on the component electric fields, an impedance matrix;
- and
- determining impedances of the unit cells such that each impedance in each unit cell is equal to a corresponding impedance in the impedance matrix.
A method for configuring unit cells of an antenna casing for an antenna based on a desired electric field for radiation, the method comprising:
- receiving a desired incident electric field to be created by the antenna;
- determining a desired scattered electric field to be created by the antenna casing, wherein the desired scattered field is equal to the desired incident electric field to be generated by the antenna minus the desired electric field;
- determining, based on the determined desired scattered electric field, a plurality of desired currents for unit cells of the antenna casing;
- discretizing, based on a geometry of the antenna casing and the plurality of desired currents, the determined desired scattered electric field into a plurality of component electric fields to be generated by the unit cells;
- determining, based on the component electric fields, an impedance matrix;
- and
- configuring impedances of the unit cells such that each impedance in each unit cell is equal to a corresponding impedance in the impedance matrix.
A system, comprising:
- an antenna configured to generate an incident electric field;
- and
- an antenna casing, coupled to the antenna, configured to generate a scattered electric field, wherein the antenna casing comprises a plurality of unit cells, wherein each unit cell in the plurality of unit cells is configured to have a different impedance from other unit cells in the plurality of unit cells, and wherein the plurality of unit cells comprise:
- a first unit cell, wherein the first unit cell is configured to have a first impedance when a first signal flows across the first unit cell at a first frequency, and
- a second unit cell coupled to the first unit cell, wherein the second unit cell is configured to have a second impedance that is different from the first impedance when a second signal flows across the second unit cell at the first frequency, wherein the antenna casing is configured to alter, based on the first impedance and the second impedance, the incident electric field into a desired electric field, wherein the desired electric field is equal to the incident electric field plus a scattered electric field generated by the antenna casing based on geometry of the antenna casing, wherein the first impedance is configured to be equal to a first ratio of the desired electric field at the surface of the first unit cell to a first surface current of the first unit cell, and wherein the second impedance is configured to be equal to a second ratio of the desired electric field at the surface of the second unit cell to a second surface current of the second unit cell.
Dependencies are inferred from the claim text.