Directive Antennas for Wide Angles of Suppression

Author: Edmund A. Laport

This section is devoted to a demonstration of certain principles that can be employed to obtain radiation patterns having wide angles of suppression. Four methods are presented by means of the solution of type problems, each of which suggests a basic principle. The suitability of any one of these principles in any specific engineering problem depends upon the nature of that problem.

FIG. 2.40. Array synthesis by successive pairings to control location of zeros.

Under the existing allocation standards of the FCC and the North American Regional Broadcasting Agreement, the problem of suppressing radiation over wide azimuth angles frequently arises. On class 1 channels the entire border of a country may have to be protected from interference, or the entire night sky-wave secondary-service area of a station must be protected. The design of antennas capable of such performance presents a special problem.

The fundamental unit of an array of this type is a pair of identical radiators with equal currents. The final array is a synthesis of several such pairs. The economical objective is to make one radiator do multiple duty by being a part of more than one basic pair.