Synthetic Aperture Radar (SAR) is an active imaging radar system that uses the motion of the radar antenna over an area to synthesize a large antenna aperture, allowing for high-resolution remote sensing images. SAR transmits radar pulses and receives the backscattered signals to generate images. The forward motion of the radar platform is used to synthesize a large antenna, providing high azimuth resolution despite using a small physical antenna. SAR operates by transmitting pulses at each position along the flight path and recording the returning echoes to build up an image. Range and azimuth resolution are determined by pulse bandwidth and antenna length respectively. SAR has many applications including cartography, geology, forestry, and environmental monitoring.

1. Synthetic Aperture Radar

 Manojkumar patley
 M.Tech_Geoinformatics (II)
 mpatley7@gmail.com

2. INTRODUCTION….
Imaging radar is an active
illumination system.
An antenna, mounted on a platform,
transmits a radar signal in a side-
looking direction towards the Earth's
surface.
 The reflected signal, known as the
echo, is backscattered from the
surface and received a fraction of a

3. INTRODUCTION…..
The term synthetic aperture radar (SAR)
derives from the fact that the motion of an
aircraft (airplane, satellite, UAV, etc.) is
used to artificially create, or synthesize a
very long, linear array.
The reason for creating a long array is to
provide the ability to resolve targets that
are closely spaced in angle, or cross range
(usually azimuth).

4. The SAR works similar of a phased
array, but contrary of a large number
of the parallel antenna elements of a
phased array, SAR uses one antenna
in time-multiplex.
The different geometric positions of
the antenna elements are result of the

5. Synthetic Aperture Radar
SAR, is a coherent mostly airborne
or spaceborne sidelooking radar
system which utilizes the flight
path of the platform to simulate an
extremely large antenna or
aperture electronically, and that
generates high-resolution remote

6. RADAR Geometry
 The incidence angle is
the angle between the
radar pulse of EMR and a
line perpendicular to the
earth’s surface where it
makes contact. When the
terrain is flat, the
complement (90Degree)
of the depression angle

7. Range = Right angle + aircraft direction of
travel
Depression angle = Horizontal +
electromagnetic pulse from antenna + G
Near- Range =
Far-Range =
Slant Range = Antenna +Target
Ground Range = Platform ground track +
Target

8. Sensor
But if possible only flat terrain

9. S A R - Principle
The forward motion of the spacecraft
to synthesise a large antenna.
This allows high azimuth resolution in
the resulting image despite a
physically small antenna.
As the radar moves, a pulse is
transmitted at each position
The return echoes pass through the
receiver and are recorded in an echo

10. S A R – Range Resolution
The range resolution of a pulsed radar
system is limited fundamentally by the
bandwidth of the transmitted pulse.
A wide bandwidth can be achieved by a short
duration pulse.
 The shorter the pulse, the lower the
transmitted energy and the poorer the
radiometric resolution.

11. S A R – Azimuth Resolution
Azimuth Resolution describes the ability of an
imaging radar to separate two closely spaced
scatters in the direction parallel to the motion
vector of the sensorThe smaller the antenna, the
larger is the beamwidth ( β = λ/D)
 Thus, the azimuthal resolution becomes
better, the smaller the antenna length D.
 Here, the smaller the antenna, the better the
resolution.
 Azimuth resolution is Xa =D/2
 The azimuthal resolution of a SAR is

13. Polarization
 IF Un Polarized energy vibrates in all
possible direction perpendicular to the

14. S A R MODE
Stripmap Spotlight Scan Mode

15. Geometric Distortion in RADAR
 Foreshortening
 Layover
 shadow

16. Specular V/S Diffuse
Reflectance

17. ResPonse of Pine tree

18. Types of the Remote Sensing Sensor

19. Commonly Used Frequency Bands

20. S A R Peaceful APPlications
 Cartography – DEM, DTM
 Geology – Geological Mapping
 Seismology – Co-seismic displacement field
 Volcanology – Prediction of volcano eruption
 Forestry – Forest classification, deforest monitoring
 Soil Science – Soil moisture
 Glaciology – Glacier motion
 Oceanography – Ocean wave, wind, circulation, bathymetry
 Agriculture – Crop monitoring
 Hydrology – Wetland assessment
 Environment – Oil spill, hazard monitoring
 Archaeology – Sub-surface mapping

21. Software

23. DEPARTMENT OF GEOGRAPHY GREEN TRICHY-CLEAN TRICHY