The Radiation Patterns Produced by a Linear Array of Half-Wave Dipoles Coupled Electromagnetically to a Two-Wire Transmission Line

Abstract

The radiation patterns produced by a linear array of half-wave dipoles coupled electromagnetically to a two-wire transmission line are analysed by an idealized theory. The effects of the various physical parameters on the radiation pattern are studied from theoretical and physical considerations. The theoretical conclusions are verified by actual measurements. In general, the radiation pattern of the antenna contains four major lobes, two in the end-fire and two in the broadside directions. The levels of the end-fire and broadside radiation can be controlled by simple means. The electromagnetic coupling principle used in this antenna array provides more flexibility for controlling the radiation pattern than in the case of the usual method of coupling the dipoles to a two-wire transmission line. A step-by-step design procedure is outlined in the end; this can be used in order to obtain the desired radiation pattern from the antenna.