Dipole with Passive Screen Reflector

Author: Edmund A. Laport

One of the simplest directive antennas is a single half-wave dipole associated with a reflecting screen of untuned wires, simulating a continuous metallic sheet, to give essentially unidirectional transmission or reception. Passive screens of practical dimensions give good gains in the forward direction and considerable suppression of backward radiation, as can be seen from Fig. 3.32. The arrangement of Fig. 3.33 is often of great utility. Assuming the screen to be infinite, its principal vertical-plane pattern is

In the horizontal plane, a half-wave dipole with reflector has the pattern

All dimensions are in electrical degrees.

A value of d between 40 and 80 degrees is desirable for good reflector action with limited screens and without excessive screen loss.