Question

If the power radiated by a quarter wave monopole is 100mW, then power radiated by a half wave dipole with doubled current is ______

(a) 800mW

(b) 400mW

(c) 200mW

(d) 100mW

I have been asked this question by my college professor while I was bunking the class.

I'm obligated to ask this question of Power Radiation from Half Wave Dipole in division Antenna Parameters – II of Antennas

Answer 1

Correct choice is (a) 800mW

To elaborate: Average Power radiated from the half-wave dipole \(P_{avg-hlf}=I_{rms}^2 R_{hlf}=4I_{rms}^2 R_{hlf}\)

⇨\(\frac{P_{avg-hlf}}{P_{avg\, mono}}=\frac{4I_{rms}^2 R_{hlf}}{I_{rms}^2 R_{mono}}=4*\frac{73}{36.5}=8\) (under same current)

Pavg-hlf=8(Pavg mono)=800mW