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Ku-band (l=2.25
cm) real-aperture radar operating with the peak power of 60 kW, the
2 kHz pulse repetition frequency and a 110 ns transmitted pulse-width.
Two cylindrical
antennas, one on each side of the aircraft, transmit and receive alternate
pulses of horizontal and vertical polarizations at large incident angles
of 72-84 to produce simultaneous HH and VV images.
The radar swath
of 12.5 km is illuminated on each side of ground track. Spatial resolution
is about 25x25 meters.
The Spaceborne Imaging Radar-C/X-band Synthetic Radar (SIR-C/X-SAR), carried in
the cargo bay of the Space Shuttle Endeavour in April and October of
1994, simultaneously recorded SAR data at three wavelengths
(L-, C-, and X-bands; 23.5, 5.8, and 3.1 cm, respectively). In addition,
the full polarimetric scattering matrix was obtained by the SIR-C
instrument at L- and C-band over a variety of terrain and vegetation
types. The integrated system is steerable in look angle (electronically
in the case of SIR-C, mechanically in the case of X-SAR) to obtain data in the angular range
of 15-16 Degree. Imaging resolution varies from about 10 to 50 meters,
depending on the geometry and data taking configuration.
Over the two flights, a total of 143 hours (93 terabits) of SAR data were digitally
recorded on tape for subsequent processing in the U.S., Germany, and
Italy. During the October 1994 flight of SIR-C/X-SAR, over one million
square kilometers of repeat-pass SAR interferometry data were also
obtained.
SIR-C/X-SAR is a cooperative experiment between the NASA (National
Aeronautics and Space Administration), the German space agency,
DARA (Deutsche Agentur fur Raumfahrtangelegenheiten), and the
Italian Space Agency, ASI (Agenzia Spaziale Italiana). SIR-C was
developed by NASA's JPL (Jet Propulsion Laboratory). X-SAR was
developed by the Dornier and Alenia Spazio companies, with the DLR
(Deutsche Forschungsanstalt fur Luft- und Raumfahrt), the major
partner in science, operations, and data processing.
Ocean-7 was launched in October 1994. It was developed at the Institute of Radiophysics and Electronics of the Ukrainian Academy of Sciences. Spatial resolution is 1-3 km within a swath of 460 km. The incidence angle changes from 21° to 46° within the swath. The RAR operates at a wavelength of 3.16 cm with vertical polarization.
The Advanced SAR (ASAR) instrument is carried by ESA's ENVISAT satellite launched on 1 March 2002. The ASAR, operated at C-band (5.331 GHz), can be regarded as an advanced version of the SAR instruments on board the ERS-1 and ERS-2 satellites. Its beam elevation steerage allow the selection of different swaths at different incidence angles, providing a swath coverage of over 400-km wide using ScanSAR techniques. In alternating polarizations mode, transmit and receive polarizations can be selected allowing scenes to be imaged simultaneously in two polarizations.
In the image mode, ASAR operates in one of seven predetermined swaths (100 km swath width) with either vertically or horizontally polarized radiation; the same polarization is used for transmit and receive (i.e., HH or VV). The ground resolution is about 30 m (three looks), sampled at pixel separation of 12.5 m.
In the alternating polarization mode (in one of seven possible swaths), two images in two polarization modes (HH & VV, or HH & HV, or VV & VH) are acquired. The ground resolution is about 30 m (1.8 equivalent number of looks), sampled at 12.5 m spacing.
When operating in the ScanSAR mode, a wide swath of > 400 km can be achieved, at a ground resolution of about 150 m (11.5 equivalent number of looks), sampled at 75 m pixel spacing.
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