Broad band antennas
First Claim
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1. A spiral antenna, comprising:
- a plurality of spiral arms, a radially inner region, a radially intermediate region, and a radially outer region, each said spiral arm having turns unmodulated in said inner and intermediate regions and radially modulated in said outer region, each said spiral arm having a spiral trace in said inner region having different parameters from the spiral trace of the same spiral arm in said intermediate region;
in which an amplitude of modulation increases progressively with angle from substantially zero at a junction between said inner and outer regions.
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Abstract
The outer turns (3) of a spiral antenna are radially modulated to extend the low-frequency response. The modulation amplitude increases progressively with spiral angle. The unmodulated region may consist of equally-spaced inner turns (1), and outer turns (2) whose spacing increases with angle. The track width of the outer turns may progressively decrease. Alternatively the track width of the outer unmodulated region may increase, the width of the modulated turns then progressively decreasing. Corresponding modulation may be applied to the outer ends of the arms of sinuous antennas.
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Citations
13 Claims
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1. A spiral antenna, comprising:
- a plurality of spiral arms, a radially inner region, a radially intermediate region, and a radially outer region, each said spiral arm having turns unmodulated in said inner and intermediate regions and radially modulated in said outer region, each said spiral arm having a spiral trace in said inner region having different parameters from the spiral trace of the same spiral arm in said intermediate region;
in which an amplitude of modulation increases progressively with angle from substantially zero at a junction between said inner and outer regions. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
- a plurality of spiral arms, a radially inner region, a radially intermediate region, and a radially outer region, each said spiral arm having turns unmodulated in said inner and intermediate regions and radially modulated in said outer region, each said spiral arm having a spiral trace in said inner region having different parameters from the spiral trace of the same spiral arm in said intermediate region;
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13. A sinuous antenna, comprising:
- a plurality of sinuous arms, a radially inner region and a radially outer region, each said sinuous arm being unmodulated in said inner region and radially modulated in said outer region, in which an amplitude of modulation in said outer region increases progressively with radial distance from substantially zero at a junction between said inner and said outer regions.
Specification