Performance assessment of straight and L-shaped probe fed U-slotted patch antenna arrays for SAR applications

In this paper the design of shaped beam antenna array for synthetic aperture array applications is presented. The proposed element for such array is an L-probe-fed U-slotted microstrip antenna. This antenna is characterized by a wideband suitable for the SAR imaging systems. The antenna element is analyzed atfirst to find out its characteristics. It has been proved that the proposed element has a bandwidth of 43% in the C-band. The mutual coupling is investigated for two adjacent elements of this type when arranged in the E-plane and again in the H-plane. It has been proved that the coupling in both arrangements is low enough to cause any significant effect on arrays arranged in the E or the H-planes. 20 elements of this antenna are arranged in the E-plane and the excitation of the elements is optimized to produce different desired beam-forms while the separation between the elements is fixed. Multiple patterns including a flat-topped beam (fan-shaped), a cosecant-squared pattern and Isoflux beam pattern have been designed and optimized using particle swarm algorithm. It turned out that this method has produced arrays with radiation patterns quite close to the desired ones and with sufficiently low side lobe levels.