A Wide-Angle Scanning and Low Sidelobe Level Microstrip Phased Array Based on Genetic Algorithm Optimization

Abstract

In order to obtain a wide-angle scanning and low sidelobe level (SLL) microstrip phased array with a finite metal ground, a novel microstrip phased array based on microstrip magnetic dipole is presented in this communication. Microstrip magnetic dipoles are employed as the driven elements in the phased array. Meanwhile, coupling patches are embedded between the adjacent driven elements, and coupling energy is transferred between driven elements by the coupling patches. Strong coupling has been constructed between elements as the driven element spacing is only about ${0}.\text{35}\; {\lambda}$ . With the influence of adjacent elements, the 3-dB beamwidth (BW) of each active element can reach over $\pm \text{80}^\circ $ in the elevation plane. From simulation and measurement, the main lobe scanning ranges of an 8-element and a 16-element phased arrays can both extend over $\pm \text{80}^\circ $ in the elevation plane with a gain fluctuation less than 3 dB. Furthermore, in order to keep the SLL low in the scanning, especially at the low elevation angles, genetic algorithm (GA) has been used, and the SLL has been decreased to the value of $- \text{9}\;\text{dB}$ in the full scanning range of $\pm \text{77}^\circ $ for the eight-element array.