To make synthetic radar (SAR), advanced radar systems are used which typically consist of a radar antenna mounted on an aircraft or satellite platform. SAR systems transmit electromagnetic waves to the Earth’s surface at microwave frequencies. As the platform moves, the radar antenna collects reflected signals bouncing off terrain or objects on the ground. These signals are recorded with the precise position of the platform at each moment. By processing the collected signals using specialized algorithms, SAR systems create high-resolution images of the Earth’s surface, enabling detailed mapping and analysis.
Synthetic aperture radar (SAR) is a radar imaging technique that uses the movement of the radar antenna (or the platform that carried it) to simulate a much larger antenna aperture. This virtual aperture allows SAR systems to achieve high spatial resolution comparable to that of a physically larger antenna. By combining multiple radar returns received from different positions along the platform path, SAR creates detailed two- and three-dimensional images of the ground, overcoming the limitations of traditional radar systems in terms of resolution and imaging capability.
The main difference between SAR (synthetic aperture radar) and SLAR (side-looking aerial radar) is their imaging methods and processing techniques. SAR uses complex algorithms to combine and process radar returns from multiple positions along the flight path to create high-resolution images. In contrast, SLAR operates with a fixed antenna pointing laterally (perpendicular to the direction of flight), capturing radar returns directly beneath the aircraft. SLAR generally provides low-resolution images compared to SAR and is less capable of producing detailed images over large areas due to its fixed viewpoint.
SAR images are formed by a process called coherent processing, which involves combining radar echoes received from multiple positions along the radar platform’s path. As the platform moves and the radar antenna transmits and receives signals, each radar return is recorded with precise timing and position data. By applying sophisticated signal processing techniques, including Fourier transform and synthetic aperture processing, SAR systems construct detailed images by focusing radar yields and suppressing noise, resulting in high-quality images that reveal surface features with fine spatial resolution.
The size of a synthetic aperture radar (SAR) system can vary depending on whether it is installed on an airborne platform (such as an airplane) or a satellite. Airborne SAR systems typically have smaller antennas due to weight and space limitations on the aircraft. Satellite SAR systems, on the other hand, can have larger antennas to achieve higher resolution imaging capabilities. The size of the SAR antenna directly affects the spatial resolution and imaging performance of the system, influencing its ability to capture fine details on the Earth’s surface during remote sensing operations.