Question

The power gain of an antenna using paraboloid reflector is directly proportional to:
1. Mouth diameter
2. Wavelength
3. Aperture ratio
4. Square of aperture ratio

Answer 1

Correct Answer - Option 3 : Aperture ratio

Effective Area:

• Effective Area ‘or’ Effective Aperture 'or' Aperture ratio is a useful parameter in calculating the receiving power of an Antenna.
• It is used to describe how much power is captured from a given plane wave.
• If ‘P’ be the power density of a plane wave and Pt represents the power at antenna terminals, then:

 

Pt = P ⋅ Ae

Ae = Effective Aperture

A general relation for effective Aperture in terms of the peak antenna gain (G) of any antenna is given by:

\({A_e} = \frac{{{\lambda ^2}}}{{4\pi }}G\)

\(G = \frac{{4\pi {A_e}}}{{{\lambda ^2}}}\)

G ∝ A_c

\(G∝\frac{1}{\lambda}\)

Observations:

1) The gain is inversely proportional to the wavelength of the signal.

2) The gain is directly proportional to the Aperture ratio A_c