Question

MHz. The dipole is made of copper wire with a radius of 1 mm (a) Determine the radiation efficiency of the antenna; (b) What is the antenna gain in decibels? (c) What antenna current is required so that the antenna will radiate 80 W, and how much power will the generator have to supply to the antenna?

Answer 1

(a) Given,

   f = 150 MHz = 150 x 10⁶ Hz

Wavelength,

     
λ 3x108 f 150 × 100 = Zin

As
11x=1/2
this is a half-wave dipole. Thus,

Rrad732

loss

π( 150 × 106)(4π × 10-7) loss = 0.5Ω 5.8 × 107

Radiation efficiency of the antenna is-

$\xi =\frac{R_{rad}}{R_{rad}+R_{loss}}$

73 730.5

$\xi =$99.3 %

(b) A half-wave dipole has a directivity of 1.64.

The antenna gain is-

     
G = D = 0.993 × 1.64 = 1.63 = 2.1dB

(c) Given,

   P_rad = 80W

Antenna Current is-

  
2,80 1.48.4 2Prad 73

Power supplied by the generator is-

   $P_{t}=\frac{P_{rad}}{\xi }=\frac{80}{0.993}=80.4W$