On-Aircraft Antennas

Abstract

Abstract : This investigation is concerned with the problem of predicting the performance of aircraft antennas which are mounted off the aircraft fuselage. In particular, the fuselage plays a very significant role in affecting the patterns (and hence the system performance) of wing or tail mounted aircraft antennas. In the present study, the aircraft fuselage is modeled theoretically by a finite length elliptic cylinder which is a satisfactory representation of a great majority of practical aircraft fuselage configurations. Hence, the study is directed toward predicting the field patterns of electric or magnetic current moments which radiate in the near zone of a finite length, perfectly-conducting elliptic cylinder. The method of analysis is based on the GTD (ray-optical) technique, and it's relevant modifications which are required in the transition regions adjacent to shadow boundaries and caustics wherein the GTD fails. The present GTD method of analysis leads to simple and accurate results; it is thus an attractive alternative to costly and time-consuming aircraft model measurements. Efficient computer codes are generated for numerical processing of the analytical results. Additional work is proposed on a problem which has arisen in the course of the present study and which merits further attention.