Satellite imaging radar
Radar systems mounted on satellites are synthetic aperture radars (SAR), and these provide side-looking images of the surface of the earth captured at wavelengths from 5cm to 1.0m. SAR wavelengths determine the scale of features in the environment they are sensitive to, for example, short wavelength systems (1-5cm) are sensitive to surface roughness features.
These system can operate any time of day or night and through smoke and cloud. Satellite radar are active systems that are mounted on a satellite. The sensor transmits an acoustic signal, which is then reflected by features on the earth surface after which the signal is received in the sensor. The frequency with which the radar signal is transmitted determines what features can be discriminated (e.g. top of mangrove canopy or underlying surface).
For a summary of satellite radar platforms see pdf.
More information
- For more information on satellite radar, refer to southport.jpl.nasa.gov or www.radartutorial.eu/index.en.html.
- More information on passive and active imaging systems.
- What is the difference between spatial, spectral and radiometric resolution?