Synthetic operation radar (SAR) works by using the movement of the radar platform (such as an aircraft or satellite) to electronically simulate a large antenna aperture. As the platform moves along a path, the SAR system transmits radar pulses to the Earth’s surface at regular intervals. Radar echoes reflected from the surface are collected by the antenna and recorded. By processing these echoes with precise timing and phase information, SAR synthesizes a high-resolution image of the terrain below the flight path. The higher the synthetic aperture (which is determined by the movement of the platform), the higher the resolution of the resulting image. This method allows SAR to achieve fine spatial resolution comparable to that of a physically larger antenna.
The SAR sensor works by transmitting microwave radar pulses to the Earth’s surface and receiving reflected echoes from objects on the ground or water. It consists of an antenna system, transmitter, receiver and signal processor. The antenna system collects radar returns over a specific swath width, while the transmitter generates the radar pulses and the receiver captures the reflected signals. The signal processor then processes these signals to form SAR images by applying algorithms that correct for platform movement, atmospheric effects and other factors that can affect image quality. This processing involves combining and focusing radar echoes to create a coherent image with high spatial resolution.
Synthetic Aperture Sonar (SAS) operates similarly to SAR but in the underwater environment. SAS uses acoustic waves instead of microwave radar pulses. It works by emitting sound waves from a sonar system towed or mounted on a mobile platform (such as a ship or underwater vehicle). Acoustic waves travel through water and reflect off objects on the seafloor or in the water column. The sonar receiver collects the reflected signals and, by processing these signals with precise timing and phase information, SAS synthesizes a high-resolution image of the seafloor or underwater objects. This technology is valuable in maritime applications such as underwater exploration, marine archeology and seabed mapping.
The fundamental principle of synthetic aperture radar (SAR) lies in the concept of aperture synthesis. SAR achieves high-resolution imaging by effectively simulating a large antenna aperture using the movement of the radar platform. As the platform moves along a path, SAR collects radar echoes from different spatial locations on the ground or water surface. By processing these echoes coherently with precise timing and phase information, SAR reconstructs a detailed image of the scene below the flight path. This capability allows SAR to achieve fine spatial resolution and overcome the physical limitations of traditional radar systems with fixed antenna apertures.
Synthetic Aperture Radar (SAR) is lateral in appearance because it works by transmitting radar pulses perpendicular to the direction of movement of the radar platform. As the platform moves forward, the radar pulses are directed laterally toward the ground or water surface at an angle. Radar echoes reflected from the surface are received by the SAR antenna, which is oriented to collect signals from the path side of the platform. This lateral orientation allows SAR to cover a wide swath on each pass and achieve complete coverage of the terrain below, making it suitable for applications requiring large area imaging and monitoring.