LENS ANTENNA :-
 TRANSMITTING MODE
 RECEVING MODE
It controls the illumination of aperture.
It collimates the electromagnetic rays.
It provides directional characteristics.
In receiving mode ,it converges the
incoming wave front at its focal point.
 It produces plane wave front form a
spherical wave front.
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Lens antenna with refractive index n>1
Lens antenna with refractive index n<1
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DEALY LENS
FAST LENS

There are two types
of lens antenna
› Delay
lances
(electrical path length
increased
by
lens
medium)
Ex. Dielectric lances,
H plane metal-plate
lenses
› Fast lances (electrical
path
length
decreased by lens
medium)
Ex. E plane metalplate lenses
Lens Antenna
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
There are two types of dielectric lenses
› Non Metallic
› Metallic/artificial
Non Metallic Dielectric lens
This types is similar to optical lens
It may designed by ray analysis methods of geometrical
optics.
Metallic or Artificial Dielectric lens
This types is less heavy compare to nonmetallic lens
It consist of discrete metal particles of macroscopic size.
Lens Antenna
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Lens Antenna
9
Lens Antenna
10
Reflection Coefficient
Lens Antenna
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Lens Antenna
12
Lens Antenna
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 A dielectric rod or wire can act as a guide for EM waves. This tendency
to radiate is turned to advantage in the polyrod antenna. (made of
Polystyrene)
Lens Antenna
14
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Curved surface zoning
Plane surface zoning
Lens are bulkier
 Design of lens antenna is complicated
 Lens are expensive

Lens antenna used as microwave antenna
 For large bandwidth requirements unstepped
dielectric lens antennas are used
 For narrow bandwidth applications ,dielectric
lens antennas are used

The incident electromagnetic waves passing around
stars are deflected through an angle which is
proportional to mass of the star and then they
brought into focus on the far side this is know as
Einsten’s gravity lens