Question

Relation between beam efficiency and stray factor is given by ____

(a) ∈B+∈s=1

(b) ∈B-∈s=1

(c) \(\frac{\in_B}{\in_s}=1\)

(d) ∈B+∈s=2

The question was asked during a job interview.

This intriguing question comes from First Null Beam Width in chapter Antenna Beam Width & Input Impedance of Antennas

Answer 1

The correct choice is (a) ∈B+∈s=1

Best explanation: Stray factor ∈s is the ratio of minor beam area to total beam area. Beam efficiency ∈B is the ratio of major beam area to total beam area. Total beam area is sum of major lobe area ΩM and minor lobe area Ωm.

\(\in_B=\frac{\Omega_M}{\Omega_A}, \in_s = \frac{\Omega_m}{\Omega_A}\)

∈B+∈s=1