Lens antenna is a microwave antenna in which a dielectric lens is placed in front of the dipole or horn radiator to concentrate the radiated energy into a narrow beam or to focus received energy on the receiving dipole or horn.

1. t
LENSANTE
NNA
Introduction | Working | Properties | Features |
Advantages & Disadvantages | Applications & Future

2. LENSE
S?
W H A T A R
E
In optics, lens is piece of glass or other transparent substance
that is used to form an image of an object by focusing rays
of light from the object. A lens is a piece of transparent
material, usually circular in shape, with two polished surfaces,
either or both of which is curved and may be either convex
(bulging) or concave (depressed).
“
”
-britannica.com

3. LENSE
S?
W H A T A R
E
O P T I C A L P R I N C I P L E S F O
R L E N S E S

4. LENSE
S?
W H A T A R
E
Lenses are classically used by engineers and scientists to
shape wave fronts. In some cases the wave fronts are
focused, while in other cases they are defocused to split
energy in different directions according to the designer's
requirements. Such lenses may be implemented in a wide
range of materials and shapes, ranging from planar 2D lenses
printed on PCB to 3D lenses made out of various dielectric
materials.
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” -http://www.feko.info

5. LENSE
S?
W H A T A R
E
EM P R I N C I P L E S F O R L E N S
E S

6. OPTICS
ANALOGY
BETWEEN
ELECTROMAGNETIC
S
&
Direction of Light

7. L E N SA N T E N N
A
A microwave antenna in which a kind of lens is placed in front
of the dipole or horn radiator to concentrate the radiated
energy into a narrow beam or to focus received energy on the
receiving dipole or horn and also whose directivity pattern is a
result of the difference between the phase velocity of
propagation of an electromagnetic wave in air and that in the
lens kind of material.

8. L E N SA N T E N N
A
Frequency Range:
The frequency range of usage of lens antenna starts at 1000
MHz but its use is greater at 3000 MHz and above.

9. L E N SA N T E N N
A
Example of a Lens Antenna

10. L E N SA N T E N N A
Functions
Following are the functions of a lens antenna
> It Generates plane wavefront from spherical
> It forms incoming wavefront at its focus
> It generates directional characteristics
> It is used to collimate electromagnetic rays

11. L E N SA N T E N N A
How Lens Works

12. L E N SA N T E N N A
Working
Operation
As shown in the transmit mode, diverging rays are collimated
which forms plane wavefront after they are incident on the lens
and have come out of it. Collimation occurs due to refraction
mechanism. It occurs in the lens with refractive index of less
than one.
As shown in the receive mode, parallel rays converge at focal
point after they have passed through lens due to refraction
mechanism.
Lens antenna is used along with point source, but practically
horn antennas are used at focal point.

13. L E N SA N T E N N ARealizationand Construction

14. L E N SA N T E N N A
Working
Operation

15. L E N SA N T E N N A
Beamwidth

16. L E N SA N T E N N A
Directivity

17. L E N SA N T E N N A
Radiation Pattern

18. L E N SA N T E N N
A
2 TYPES
As shown spherical wavefront produced by
primary feed antenna is converted into
plane wavefront by dielectric lens. It is also
known as delay lens antenna due to the
fact that outgoing EM rays are collimated &
delayed by lens material.
DIELECTRIC LENS ANTENNA
Following are the features of dielectric lens antenna:
> It is useful at higher frequencies, it becomes heavy and bulky at
frequencies less than 3 GHz.
> It is made of polystyrene or lucite & polyethylene.

19. L E N SA N T E N N
A
2 TYPES
In this type of lens antenna, spherical
wavefront is converted into plane
wavefront but here outgoing wavefront is
speeded up by material of lens. The same
operation as Dielectric Lens Antenna.
METAL PLATE LENS ANTENNA
Following are the features of metal plate lens antenna:
> It is constructed for a high-power microwave zoom antenna.
> It is easiest to build, cheap and integrate

20. L E N SA N T E N N
A
2 TYPES
In this type of lens antenna, spherical
wavefront is converted into plane
wavefront but here outgoing wavefront is
speeded up by material of lens. The same
operation as Dielectric Lens Antenna.
METAL PLATE LENS ANTENNA
Following are the features of metal plate lens antenna:
> It is constructed for a high-power microwave zoom antenna.
> It is easiest to build, cheap and integrate

21. L E N SA N T E N N
A
+ &-
> In lens antennas, feed and feed support, do not obstruct the
aperture.
> It has greater design tolerance.
> Larger amount of wave, than a parabolic reflector, can be
handled.
> Beam can be moved angularly with respect to the axis.
ADVANTAGES
> Lenses are heavy and bulky, especially at lower frequencies
> Complexity in design
> Costlier compared to reflectors, for same gain/bandwidth in
comparison to reflector antenna.
> Expensive as compared to Reflector Antenna
DISADVANTAGES

22. L E N SA N T E N N
A
+ &-
> Used as wide band antenna
> Especially used for Microwave frequency applications
> Smart Lens Antenna for Projection of Beam
> Microwave Transmission and Reception Applications
APPLICATIONS

23. E N D
Sources
http://www.feko.info/applications/antenna-analysis/lens-
antennas
http://www.tutorialspoint.com/antenna_theory/antenna_the
ory_lens.htm
http://electriciantraining.tpub.com/14183/css/Lens-
Antennas-156.htm
http://www.rfwireless-world.com/Articles/Lens-Antenna-
basics-and-types.html
https://www.cst.com/Applications/Article/A-Dielectric-Lens-
Antenna-With-Enhanced-Aperture-Efficiency-For-Industrial-
Radar-Applications