What minimum power level at the backward direction is expected for an efficient beam antenna?

The minimum power level in the backward direction, expected for an efficient beam antenna, is 6 dB. This value is significant because it indicates that the antenna is designed to significantly reject energy radiating in the backward direction compared to the forward direction.

In antenna terminology, the term "beam width" describes how focused or directionally efficient an antenna is. A 6 dB drop in power level in the backward direction suggests that the antenna is effectively directing at least four times more energy in the forward direction than in the backward direction. This is a critical performance metric for beam antennas, which are aimed at providing enhanced coverage and minimizing interference from unwanted signals coming from the rear.

Maximum efficiency in beam antennas typically reflects a balance between gain, directivity, and the radiating pattern. While higher gains, such as 9 dB or 12 dB, may suggest even more focused radiation patterns, the key benchmark for determining effective backward rejection starts at 6 dB. This level indicates that the antenna can be effectively utilized in practical applications for communication while maintaining its directive characteristics.