Multi-frequency antenna feed
First Claim
1. A single antenna feed structure having a first central waveguide operating at a first frequency band and at least one outer waveguide substantially coaxial with the central waveguide and operating at a second frequency band, said first waveguide being excited by excitation means disposed in said waveguide, and said second waveguide being excited by radiation from a non-circular waveguide feed structure disposed orthogonally to the longitudinal axis of the outer waveguide and including a first feed for horizontally polarized signals and a second feed for vertically polarized signals so as to set up respective horizontally and vertically polarized fields in said at least one outer waveguide and said feed structure having an isolation bar disposed in the outer waveguide and between an outer surface of the inner central waveguide and an inner surface of the outer coaxial waveguide on both sides of the inner waveguide and in a plane orthogonal to the first and second non-circular waveguides, and signal rotation means disposed in said outer waveguide for rotating the polarized signals in said outer waveguide.
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Abstract
A multi-frequency antenna feed for incorporation into a single unit which combines at least two waveguides to provide simultaneous reception and/or transmission of signals in at least two separate frequency bands is described.
This is achieved by creating a waveguide system of at least two waveguides sharing the same central axis; a central conventional waveguide which also acts as a center conductor for an outer coaxial waveguide and feeding the outer coaxial waveguide from a non-circular side feed, orthogonal to the waveguide axis, to set up a uniform field in the outer coaxial waveguide. The feeds are adjusted so that the phase center for each frequency band is at the same point in the feed for the same dish. Various embodiments of the invention are described.
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Citations
44 Claims
- 1. A single antenna feed structure having a first central waveguide operating at a first frequency band and at least one outer waveguide substantially coaxial with the central waveguide and operating at a second frequency band, said first waveguide being excited by excitation means disposed in said waveguide, and said second waveguide being excited by radiation from a non-circular waveguide feed structure disposed orthogonally to the longitudinal axis of the outer waveguide and including a first feed for horizontally polarized signals and a second feed for vertically polarized signals so as to set up respective horizontally and vertically polarized fields in said at least one outer waveguide and said feed structure having an isolation bar disposed in the outer waveguide and between an outer surface of the inner central waveguide and an inner surface of the outer coaxial waveguide on both sides of the inner waveguide and in a plane orthogonal to the first and second non-circular waveguides, and signal rotation means disposed in said outer waveguide for rotating the polarized signals in said outer waveguide.
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43. A method of providing communication from at least two separate frequency bands in a single antenna feed device, said method comprising the steps of,
providing a first central waveguide adapted for at least one of receiving and transmitting over a first frequency band, providing a second waveguide surrounding said first waveguide and coaxial with said first waveguide for at least one of receiving and/or transmitting at a second frequency band, said second frequency band being lower than said first frequency band, providing a feed structure disposed orthogonally to the longitudinal axis of the second waveguide and including a first feed for horizontally polarized signals and a second feed for vertically polarized signals so as to set up respective horizontally and vertically polarized fields in said second waveguide, said feed structure having an isolation bar disposed in the second waveguide and between an outer surface of the first waveguide and an inner surface of the second waveguide on both sides of the first waveguide and in a plane orthogonal to the first and second waveguides, providing signal rotation means disposed in said second waveguide for rotating the polarized signals in said second waveguide, exciting said first waveguide by at least a single probe disposed in said waveguide to create a uniform field within said first waveguide, and exciting said second waveguide by feeding incident radiation into said outer waveguide in a direction orthogonal to the axis of said waveguide to create a uniform field within said outer coaxial waveguide.
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44. A multi-frequency band receive/transmit antenna feed comprising a first central waveguide operating at a first frequency band and at least one outer waveguide substantially coaxial with the central waveguide and operating at a second frequency band, said first waveguide being excited by excitation means disposed in said waveguide, and said outer waveguide being excited by radiation from a non-circular waveguide feed structure disposed orthogonally to the longitudinal axis of the outer waveguide and including a first feed for horizontally polarized signals and a second feed for vertically polarized signals so as to set up respective horizontally and vertically polarized fields in said at least one outer coaxial waveguide, and said feed structure having an isolation bar disposed in the outer waveguide and between an outer surface of the inner waveguide and an inner surface of the outer waveguide on both sides of the inner waveguide and in a plane orthogonal to the first and second waveguides, and a second signal rotation means disposed in said outer waveguide for rotating the polarized signals in said outer waveguide, whereby said antenna feed can one of receive signals in said different frequency bands, and receive/transmit signals in said different frequency bands.
Specification