ELECTRICAL CHARACTERISTICS OF A HARDENABLE, CIRCULARLY POLARIZED METALLIC LENS ANTENNA.
Rept. Jul 68-Jun 69,
AEROSPACE CORP EL SEGUNDO CALIF OFFICE FOR TECHNOLOGY
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A lens antenna consisting of a circular matrix of square waveguides was proposed as a potential candidate for the hardened ground antenna in a satellite-ground communication link. Square waveguides were used for supporting circular polarization, which was found most effective in satellite-ground communication links. The purpose of the present study was to investigate unknown electrical characteristics and determine some of the important electrical properties of a 3-ft-diam scaled model antenna. The lens was designed for operation at 10 GHz with an equivalent index of refraction of 0.5. Antenna efficiency and other electrical parameters, such as radiation patterns, gain, bandwidth, scan capability, and VSWR, were investigated. The on-axis characteristics were determined over a 10 frequency range. The antenna efficiency varied from 38 to 43.5, and sidelobe levels were at least 20 dB below the main beam over this frequency range. Different feed horn sizes were employed to obtain an optimum aperture illumination. Antenna characteristics were determined for various beam scan angles to 21.5 degrees or 9.1 beamwidths. For a 3-dB drop in gain, the antenna beam can be steered to an angle of 18 degrees or 7.65 beamwidths. The deterioration in antenna performance with scan is also shown. Some preliminary results are presented for lens performance as affected by a feed enclosure back plate and an aperture blockage. Author
- Electrical and Electronic Equipment