Mumbai University > Electronics Engineering > Sem 5 > Electromagnetic Engineering

Marks: 5 Marks

Year: Dec 2014

When current is passed through antenna, it radiates more in one direction and less in other directions. This is called radition property of antenna. All antenna possess certain basic properties.

Radition Pattern:

It is a graphical representation of the radition (far field) property of an antenna.

Isotropic antenna radiates equally in all the direction.

Directional antenna radiates more in a particular direction and less in other. Omni directional antenna has essentially a non- directional pattern in a given plane and directional pattern in any orthogonal plane.

Half power beam width:

It is defined as the angular distance between two points on antenna pattern 3dB below the maximum gain points.

First null beam width:

It is defined as the angular distance between two points on each side of major lobe where radiation drops to zero.

Side lobe level:

Ratio of pattern value of side lobe peck to the pattern value of main lobe is known as side lobe level.

Front to back ratio:

Ratio of antenna gain at 0° and 180°.

Beam area:

It is defined as a solid angle from which radiating power flous.

$Ω_A= Ω_M+ Ω_m$

Where,

$Ω_A →$ Total beam area

$Ω_M →$ Main lobe beam area

$Ω_m →$ Minor lobe beam area