Directional MF antennas using self-supporting towers with driven wire cages

An examination is made of the synthesis of directional high-power MF antennas that comprise grounded self-supporting steel towers with driven wire cages as radiating elements. Advantages of this radiator concept are discussed. Computer models of such radiator for the method of moments (MM) analysis of synthesis for an antenna of n radiators is achieved by (1) MM analysis of the antenna for n independent modes, and (2) applying an optimization procedure to determine n complex coefficients for superposition of the modes to obtain an optimal approximation to a specified pattern. Aspects for selecting the modes are discussed. Two examples, namely, antennas with two and four towers, and the theoretical models of their radiators are presented. The patterns measured by helicopter show very close agreement to the theoretical patterns