As an active
sensor, RADARSAT’s Synthetic Aperture Radar (SAR) transmits
a microwave energy pulse to the earth. The SAR measures the
amount of energy which returns to the satellite after it
interacts with the earth’s surface. Unlike optical
sensors, microwave energy penetrates darkness, clouds, rain,
dust or haze, enabling RADARSAT to collect data under any
atmospheric condition.
RADARSAT transmits its C-band microwave energy in a horizontal
orientation (known as polarisation). The energy which returns
to RADARSAT’s sensor is captured using the same polarisation.
This is known as HH polarisation system. Variations in the
returned signal (backscatter) are a result of variations
in the surface roughness and topography as well as physical
properties such as moisture content.
There are applications in which the alignment and orientation
of features are of particular interest. These include the
mapping of geological lineaments and structures, analysis
of agricultural tillage and crop planting practices, drainage
patterns and mapping of cultural features such as roads and
railways. The direction from which these features are viewed
can affect how easily these features are identified on the
resulting images.
The detection of linear features is enhanced when they are
aligned near-perpendicular to the look direction of the satellite.
Conversely, linear features can be suppressed if aligned
parallel to the look direction. RADARSAT’s look direction
will vary with latitude. RADARSAT can produce 25 possible
choices of images; each varies with respect to the area covered
and the angle at which the earth’s surface is viewed.
RADARSAT transmits its C-band microwave energy in a horizontal
orientation (known as polarisation). The energy which returns
to RADARSAT’s sensor is captured using the same polarisation.
This is known as HH polarisation system. Variations in the
returned signal (backscatter) are a result of variations
in the surface roughness and topography as well as physical
properties such as moisture content. 
