31-08-2017, 01:54 PM
Synthetic aperture radar (SAR) is a form of radar that is used to create two-dimensional or three-dimensional images of objects, such as landscapes. SAR uses the movement of the radar antenna over a target region to provide finer spatial resolution than conventional beam scanning radars. SAR is typically mounted on a mobile platform, such as an aircraft or spacecraft, and has its origins in an advanced form of Side-looking Airborne Radar (SLAR). The distance traveled by the SAR device over a target in the time required for the radar pulses to return to the antenna creates the large aperture of the "synthetic" antenna (the "size" of the antenna). Typically, the larger the aperture, the higher the image resolution, regardless of whether the aperture is physical (a large antenna) or "synthetic" (a mobile antenna) - this allows SAR to create high resolution images with comparatively small physical size antennas
To create a SAR image, successive radio wave pulses are transmitted to "illuminate" a target scene and the echo of each pulse is received and recorded. The pulses are transmitted and received echoes using a single beam-forming antenna, with wavelengths of one meter to several millimeters. As the SAR device moves aboard the aircraft or spacecraft, the location of the antenna relative to the target changes over time. The processing of signals from successive recorded radar echoes allows to combine the recordings of these multiple antenna positions - this process forms the "synthetic antenna aperture" and allows the creation of images of higher resolution than would be possible with a physical antenna Dadaist.
Current airborne (2010) systems provide resolutions of approximately 10 cm, ultra-wideband systems provide resolutions of a few millimeters, and the experimental terahertz SAR has provided a sub-millimeter resolution in the laboratory.
To create a SAR image, successive radio wave pulses are transmitted to "illuminate" a target scene and the echo of each pulse is received and recorded. The pulses are transmitted and received echoes using a single beam-forming antenna, with wavelengths of one meter to several millimeters. As the SAR device moves aboard the aircraft or spacecraft, the location of the antenna relative to the target changes over time. The processing of signals from successive recorded radar echoes allows to combine the recordings of these multiple antenna positions - this process forms the "synthetic antenna aperture" and allows the creation of images of higher resolution than would be possible with a physical antenna Dadaist.
Current airborne (2010) systems provide resolutions of approximately 10 cm, ultra-wideband systems provide resolutions of a few millimeters, and the experimental terahertz SAR has provided a sub-millimeter resolution in the laboratory.