Question

A mast antenna consisting of a 50 m long vertical conductor operates over a perfetly conducting ground plane. It is base-fed at a frequency of 600 kHz. The radiation resistance of the antenna (in $\Omega$) is_____.

• A. 3.95
• B. 3.95
• C. 3.95
• D. 3.95

Answer 1

The correct option is C 3.95

as it is on conducting plane

$R_{rad}=40{\pi }^2{\left(\frac{dl}{\lambda }\right)}^2$

dl = 50 m

$\lambda =\frac{3\times {10}^8}{6\times {10}^5}=\frac{1}{2}\times {10}^3=500$

$\frac{dl}{\lambda }=\frac{50}{500}=\frac{1}{10}$

$R_{rad}=40{\pi }^2\times \frac{1}{100}$

$=3.9478\Omega$