The desirable features of antenna for Airborne SAR applications include shaped radiation pattern and wide bandwidth capability, good cross polarization isolation and high power capability. Shaped radiation across the track improves the target dynamic range and compensates the requirement of STC (Sensitivity Time Control) correction at receiver end. Wide bandwidth performance results in finer resolution. Planar array antenna is preferred as compared to reflector type antenna for less air drag.
Proper selection of radiating element for planar array dictates the requirement of large bandwidth, low cross polarization with high gain. Multilayer electromagnetically coupled printed antenna is selected, which overcomes the bandwidth limitation of the conventional Microstrip antenna. Aperture coupled antenna although offers the advantage of optimizing feeder network and patch independently, but the impedance matching is poor due to improper grounding when coaxial feeding below the ground is required for the array.
Proper selection of radiating element for planar array dictates the requirement of large bandwidth, low cross polarization with high gain. Multilayer electromagnetically coupled printed antenna is selected, which overcomes the bandwidth limitation of the conventional Microstrip antenna. Aperture coupled antenna although offers the advantage of optimizing feeder network and patch independently, but the impedance matching is poor due to improper grounding when coaxial feeding below the ground is required for the array.
