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Title: Dual-frequency circularly polarized spiral antenna for satellite navigation
Claims: What is claimed is: 1. An omnidirectional circularly polarized antenna for satellite communication and the like having, in combination, a longitudinal insulating member; transmission-line means extending longitudinally within said member and connected near the ends of said member and at an intermediate position thereof to transversely extending conductive feed connector means; first and second interleaved sets of substantially parallel conductive strips extending longitudinally along the member; means for connecting adjacent strips of the first and second sets together at one of their ends near one end of said member and to the said connector means near said one end of the member; means for connecting the other ends of the first set of strips to the said connector means near said other end of said member; and means for connecting the other ends of the second set of strips to said connector means at the said intermediate position in order to produce substantially the same omnidirectional pattern of radiation coverage directed upward of said member and over a band of wavelengths including those corresponding to the dimensions of the strips of said first and second sets of strips. 2. An omnidirectional antenna as claimed in claim 1 and in which said strips extend spirally longitudinally along said member. 3. An omnidirectional antenna as claimed in claim 2 and in which said strips are substantially equally transversely spaced. 4. An omnidirectional antenna as claimed in claim 1 and in which the strips of said first set are longer than those of said second set, with the lengths adjusted to values slightly different from the half wavelengths of lower and higher frequencies in said band. 5. An omnidirectional antenna as claimed in claim 1, and in which means is provided for varying the length of said member and its strips to vary the direction of maximum vertical response; the shorter the member, the closer said direction to the longitudinal axis of said member. 6. An omnidirectional antenna as claimed in claim 2 and in which said transmission-line means comprises a longitudinal coaxial line and said connector means comprise a plurality of transversely extending spokelike feed connectors emanating from said line. 7. An omnidirectional antenna as claimed in claim 2 and in which the direction of the spiral is adjusted for the desired type of circular polarization of the said radiation. 8. An onmidirectional antenna as claimed in claim 1 and in which the distance between one end of said member and the intermediate position is several times that between said intermediate position and the other end of said member. 9. An omnidirectional antenna as claimed in claim 8 and in which the strips of said first set extend between the ends of said member. Other info: Inventors: Smith, Valor Clark (LeMesa, CA, US) Application Number: 628047 Filing Date: 1975-11-03 Publication_date: 1977-02-15 Assignee: CHU Associates, Inc. (Littleton, MA) Primary Class(es): 343/895 343/873 Other Classes: US Patent Ref:
Other Refs: Primary Examiner: Lieberman, Eli Assistant Examiner: Attorney: Rines and Rines |
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