Study of Antenna Pattern Coverage for a UHF Antenna System on an Aircraft.

摘要

An idealized study of theoretical patterns of a four-element crossed-slot array on a cylinder approximating the fuselage of a KC-135aircraft has been carried out. The objective is to obtain complete hemispherical coverage with at least 6dB gain for circular polarization over the band from 250to 400MHz. The study shows that 15beam positions,requiring switching each antenna between 0degrees and three values of phase shift,will give nearly the desired coverage. Coverage is limited over a small portion of the region,primarily in the fore-aft directions,because of the drop in gain of the individual array elements in these directions. An optimum location for the array on the side of the fuselage is chosen at an angle of 60degrees from the zenith. (A similar array is required on the opposite side of the aircraft to give coverage on the other side). The effects of multipath reflections are calculated and found to be negligible because of the circular polarization discrimination of the antenna. (Author)