Question

A broadside array operating at 100 cm wavelength consist of 4 half wave dipoles spaced 50 cm apart.

Each element carries radio frequency current in the same phase and of magnitude 0.5 A. The radiated power will be _______ if the radiation resistance is 146 ohm.

1. 146 W
2. 73 W
3. 36.5 W
4. 18.25 W

Answer 1

Correct Answer - Option 2 : 73 W

Given:

I_m = 0.5 Amp

Radiation Resistance, R_rad = 146 Ω

Calculation:

Power radiated by 1 half-wave dipole antenna. 

\({P_{rad}} = \frac{1}{2}\;I_m^2 \times {R_{rad}}\)

= 18.25 watt

∴ Total power radiated by 4 half-wave dipole antenna.

P_T = 4 P_rad = 73 W