Traveling-wave feeder type coaxial slot antenna
AssigneeBeam, Inc.
InventorKoichi Wada
Life of this patent
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Abstract
A traveling-wave feeder type coaxial slot antenna, comprising: a central conductor extending over a certain length; a cylindrical outer conductor coaxially surrounding the central conductor; and a plurality of slots provided in the outer conductor at a certain inclination angle, for instance 45 degrees, relative to a longitudinal axis of the outer conductor. This antenna can be conveniently fabricated from a commercially available coaxial cable. By suitable selection of the inclination angle of the slots and their mutual spacing, the antenna may be provided with a directivity directed to a desired elevation angle when mounted on a vertical wall to make is suitable for receiving radio wave signals from a satellite.
Claims15
A travelling-wave feeder type coaxial slot antenna, comprising:
- a central conductor;
- a cylindrical outer conductor coaxially surrounding the central conductor;
- an insulator separating the central conductor from the outer conductor;
- and
- a plurality of slots provided in the outer conductor, each of the slots extending at an angle relative to a longitudinal axis of the outer conductor so as to obtain a desired directivity and wave polarizations;
- wherein the inner diameter D of the outer conductor satisfies the following conditions:
- ##EQU11## wherein .epsilon. r is the relative dielectric constant of the insulator separating said central conductor from said outer conductor, .function. is the transmission frequency and is greater than 1 GHz, Z.sub.0 is a characteristic impedance of the antenna, V.sub.0 is the free space velocity of a radio wave generated from the slots, .lambda..sub.0 is the wave length in free space of the radio wave generated from the slots, and .theta..sub.MAX is the maximum angle of said slots relative to the longitudinal axis of said outer conductor.
Dependencies are inferred from the claim text.