Question

What is the phase excitation difference in end-fire array with array spacing d at  θ=0°?

(a) \(-\frac{2π}{λ} d \)

(b) \(\frac{2π}{λ} d \)

(c) \(-\frac{π}{λ} d \)

(d) \(\frac{π}{λ} d \)

This question was addressed to me in an interview for internship.

I'm obligated to ask this question of End Fire Array in portion Antenna Array of Antennas

Answer 1

The correct choice is (a) \(-\frac{2π}{λ} d \)

Easiest explanation: In end-fire array the phase excitation difference is –kd for θ=0°.

kdcosθ+β=0

β=-kd

\(β=-\frac{2π}{λ} d \)