Question

What is the phase excitation difference for an end-fire array?

(a) 0

(b) ±kd /2

(c) π

(d) ±kd

I had been asked this question during an internship interview.

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

Answer 1

Right option is (d) ±kd

Best explanation: The maximum array factor occurs when \(\frac{sin \frac{Nφ}{2}}{\frac{Nφ}{2}}\) maximum that is \(\frac{Nφ}{2}=0. \)

And φ=kdcosθ+β

=> kdcosθ+β=0 For an end-fire array maximum radiation is along the axis of array so

 θ=0° or 180°

=> β=kd when θ=180°

=> β=-kd when θ=0°