RF Designs and Simulations

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. More Detail: Microstrip and Printed Antenna Design

Multi-layer Microstrip Antenna Generally impedance bandwidth of patch antennas varies from 2-3% for single layer direct coupling or probe coupling  and can be further enhanced by coupling the power from the strip line through an aperture (slot) in the ground plane and/or printing patch effectively on the foam material whose dielectric constant is nearly equal to that of air [. In such case the feed network is isolated from the radiating element by a ground plane, which prevents spurious radiation. The resonant or non-resonant slot couples energy from the stripline to the patch. If slot is resonant, it provides another resonance in addition to the patch resonance, resulting in an antenna with 10-15% impedance bandwidth. However, the resonant slot has strong backlobe, which substantially reduces the gain of the antenna. Non-resonant slot has better front to back ratio, which results in improvement in efficiency with narrow bandwidth. Hence multilayer microstrip antennas are di...