Microwave Sensing RADAR

Microwave data can be obtained by both active and passive systems. Passive system monitor natural radiation at a particular frequency or range of frequency. Data may be presented numerically as line trace data or as imagery. Active systems (like SLAR and SAR) transmit their own energy and monitor the returned signal.

Characteristics of such radar imagery both in SAR and SLAR and their resolution depends on various parameters like frequency of the signal, look direction, slant range, dielectric constant of the objects, phase, antenna length etc. Spatial resolution in range and azimuth direction varies in different manners.

RADAR (SAR) imageries have been obtained from satellite SEASAT, ERS and space shuttle missions SIR-A, SIR-B and SIR-C using synthatic aperture radar, which have all weather capability. Such data products are useful for studies in cloud-covered region of the earth and in oceanography.

Table 2. Microwave Sensors

Seasat SAR

SIR-C/X-SAR

ESA SAR

RADARSAT SAR

ENVISAT ASAR

JERS-1

Frequency

1.275 GHz

5.3 GHz 1.275 GHz

5.3 GHz

5.33 GHz

5.33 GHz

1.275 GHz

Wave length

L band 23 cm

X band 3 cm C band 6 cm L band 23 cm

C band

C band

C band

L Band (23 cm)

Swath Width

100 km, centered 20o off nadir

15 to 90 km Depend on orientation is antenna

100 km Varies

75 km

Ground Resolution

25 x 25 m

10 to 200 m

30 m

100x100 m to 9x9 m Varies

Varies

30 m

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