Question

What happens to the beam-width of antenna if the frequency of operation is increased?

(a) Beam-width will decrease

(b) Beam-width will increase

(c) Beam-width is independent of frequency

(d) Beam width may increase or decrease

The question was posed to me in a job interview.

This intriguing question comes from Half Power Beam Width topic in division Antenna Beam Width & Input Impedance of Antennas

Answer 1

The correct option is (a) Beam-width will decrease

Explanation: If frequency is high, power radiated is low (From Radar range equation). That means directivity is high as \(D=\frac{4\pi U}{P_{rad}}.\) Beam width and directivity are inversely proportional to each other. So beam width will be low.