Question

An antenna behave as resonant circuit only when its length is :

• A. $\frac{\lambda }{2}$
• B. $\frac{\lambda }{4}$
• C. $\lambda$
• D. $\frac{\lambda }{2}$ or integral multiple of $\frac{\lambda }{2}$

Answer 1

Answer: (D)

$\frac{\lambda }{2}$ or integral multiple of $\frac{\lambda }{2}$

Condition for resonance : The length of the antenna should compose of n nodes and ( n + 1 ) antinodes.

Hence , $l$ = $\frac{n\lambda }{2}$ .Therefore , antenna length must be $\frac{\lambda }{2}$ or integral multiple of $\frac{\lambda }{2}$ .