SAR
Principles
Small satellites with synthetic aperture radar (SAR) payloads are a growing trend in the satellite industry. The long pathlength traveled by the satellite in orbit acts as a large virtual antenna enabling meter and even sub-meter resolution imaging. Spaceborne SAR is an active system that yields high-resolution images of Earth's surface. SAR takes advantage of properties of EM waves to penetrate clouds, foliage and even upper layers of Earth's surface.The technique is based on constructive coherent processing of the EM wave echoes reflected back from Earth's surface.
Features

EOS SAR satellites will operate in Stripmap, Spotlight, and Interferometric modes that will support wide range of applications.

The satellites are designed to achieve high operational efficiency and allow for rapid deployment of dual- and multi-frequency SAR constellations. Dual-band operation ( X- and S-band) increases versatility for all weather conditions and improves object-ground contrast. Special configuration of the radar front end allows for imaging of selected areas in both bands in a single orbit.

EOS is building a SAR satellite payload suitable for constellations enabling high revisit rates.

A constellation of 12 satellites will enable 2–3 hours revisit time for a given area.

Formation flying with optical satellites is under development for more efficient utilization of satellite resources. In addition, the combination of SAR and optical images enriches the informational content of satellite products.

Modes of operation
Deployed
Stowed
Light-weight deployable reflector antenna

Benefits of reflector antenna

  • less complex wrt phased array
  • polarization invariant
  • multifrequency operation
  • larger aperture => better SNR or lower Tx power
  • low weight
  • simpler signal processing (fewer signals to process) => power savings
  • long lifetime

More information

SAR payload

Technical characteristics

  • light-weight deployable reflector antenna
  • multibeam operation enabling wide swath
  • high resolution (as low as 25 cm)
  • dual-band operation (X- and S-bands)
  • dual linear polarization (HV, VV)
  • 50 kg SAR payload weight
  • Stripmap, Spotlight and Interferemetric modes
Dual band performance

X- and S-band

  • dual band operation allows for any weather imaging
  • diversifies image acquisition
  • special antenna design allows dual band imaging of selected areas in a single orbit
  • provides better image contrast

X-Band

  • high resolution imaging
  • target identification
  • object classification
  • DEM and topography

S-Band

  • higher penetration capabilities (foliage, ground)
  • lower rain attenuation
  • soil moisture and crop classification
  • higher contrast for reflective objects
Vision for project stages
Parameter
Operating band
Resolution, m
Antenna type
Swath width, km
Polarization
Imaging time per orbit, min
Modes
Bandwidth, MHz
Number of beams / feeds
Weight, kg
Launch year
1st satellite
X
2x2 / 1x0.25
Mesh reflector
20
Linear
5
Stripmap / Spotlight
300
4
150
2021
2nd satellite
X S
1x1 / 0.5x0.25 5x5
Mesh reflector
20 25
Linear
5 5
Stripmap / Spotlight / ScanSAR Stripmap / Spotlight
600 100
4+4 2
200
2022
3rd satellite
X S
1x0.5 / 0.25x0.25 3x3
2 x Mesh reflectors Mesh reflector
40 25
Linear Dual linear
5 5
Stripmap / Spotlight / ScanSAR Stripmap / Spotlight
1200 200
4+4 2+2
250
2023-24
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