Question

The ratio of radiation intensity in a given direction from antenna to the radiation intensity over all directions is called as ________

(a) Directivity

(b) Radiation power density

(c) Gain of antenna

(d) Array Factor

I had been asked this question in an online interview.

Origin of the question is Basics topic in section Antenna Parameters of Antennas

Answer 1

Correct option is (a) Directivity

To explain: Directivity of antenna is defined as the ratio of radiation intensity in a given direction from antenna to the radiation intensity over all directions. \(D = \frac{U_{max}}{U_0}.\)

 Radiation Intensity is power radiated from an antenna for unit solid angle. \(U_0= w_r.r^2\frac{watts}{steradians}.\)

Gain of antenna is ratio of radiation intensity in given direction to the radiation intensity of isotropic radiation. Array factor is a function of geometry of array and the excitation phase.