MCQ
A signal is to be transmitted through a wave of wavelength $\lambda $, using a linear antenna. The length $l$ of the antenna and effective power radiated $P_{eff}$ will be given respectively as : ($K$ is a constant of proportionality)
  • $\lambda ,{P_{eff}} = K{\left( {\frac{1}{\lambda }} \right)^2}$
  • B
    $\frac{\lambda }{8},{P_{eff}} = K\left( {\frac{1}{\lambda }} \right)$
  • C
    $\frac{\lambda }{{16}},{P_{eff}} = K{\left( {\frac{1}{\lambda }} \right)^3}$
  • D
    $\frac{\lambda }{5},{P_{eff}} = K{\left( {\frac{1}{\lambda }} \right)^{\frac{1}{2}}}$

Answer

Correct option: A.
$\lambda ,{P_{eff}} = K{\left( {\frac{1}{\lambda }} \right)^2}$
a
Length of antenna = comparable to $\lambda $

Power radiated by linear antenna inversely depends on the square of wavelength and directly on the length of the antenna. Hence

Power $P = \mu {\left( {\frac{1}{\lambda }} \right)^2}$  here $\mu \, = K$

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