Question

The radiation resistance of a monopole is _____ times the current element.

(a) 1/8

(b) 1/4

(c) 1/2

(d) 1/16

The question was posed to me during an internship interview.

I need to ask this question from Radiation in portion Radiation, Baluns & Polarization of Antennas

Answer 1

Right choice is (a) 1/8

Easiest explanation: The radiation resistance of monopole is ½ times the short dipole. But the radiation resistance of short dipole is ¼ time the current element.

\(R_{rad \,mono}=\frac{1}{2}×\frac{1}{4}×80\pi^2(\frac{l}{\lambda})^2=\frac{1}{8}×80\pi^2(\frac{l}{\lambda})^2=10\pi^2 (\frac{l}{\lambda})^2=\frac{R_{rad \,Herztian}}{8}\)

The radiation resistance of monopole is 1/8 times the current element.