| Popis: |
The design and experimental optimization of a canister antenna for operation in the 17.7 to 19.7 GHz frequency band are described. The canister is specifically designed to accommodate the antenna, transmitter and receiver units, and to be aesthetically innocuous in its environment. The basic antenna configuration, that of a shielded inverted periscope, is reviewed. Details of the constituent parts of the antenna, including dual mode feed, paraboloidal reflector, mirror, radome, and microwave absorber are presented. The influence that each of these items plays in determining net electrical performance is identified, including (where appropriate) steps taken to achieve electrical optimization. The antenna is shown to afford excellent sidelobe suppression, azimuthal plane cross polarization discrimination in the mid to upper 30 dB range, and a return loss of better than 23 dB. The gain efficiency is approximately 62 percent and is essentially polarization independent. |
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