# The length of half wave dipole antenna needed for a 200MHz signal is

$\begin{array}{1 1}(a)\;\text{10 m}\\(b)\; \text{1 m}\\(c)\;\text{0.75 m}\\(d)\;\text{2.5 m}\end{array}$

Frequency of signal =200 MHz=$200\times 10^6$Hz
Wave length $\lambda=\large\frac{\text{Speed of light}}{\text{Frequency}}$
$\Rightarrow \large\frac{3\times 10^8m/s}{200\times 10^6/s}$
$\Rightarrow 1.5m$
Length of half wave dipole $=\large\frac{\lambda}{2}=\frac{1.5}{2}$$=0.75m$
Hence (c) is the correct option.