Low-Scattering-Sidelobe Phased Array Antenna With Improved Radiation Performance

In this article, the formulas to compute phased array scattering fields under oblique incidences are derived as the theoretical basis of scattering sidelobe level (SLL) reduction. Meanwhile, in order to improve antenna radiation performance, the way to compute and evaluate array impedance matching performance is proposed based on an equivalent network model. The accuracy and efficiency of the formulas applied to predict array scattering fields and reflection coefficients are well validated by numerical study. Furthermore, a microstrip phased array antenna with a tapered array shape and optimized element feed networks is designed. A modified particle swarm optimization algorithm is proposed to search the solution of feed networks to reduce monostatic scattering SLL and improve antenna impedance matching simultaneously, where the proposed fast prediction approaches are employed. The optimized phased array antenna features scattering SLL reduction by 8.8 dB in the concerned angular range of 10°–30° and in the operating band of 5.5–7.5 GHz against its conventional counterpart, with improved impedance matching and slightly higher gains. Eventually, the numerical results are well validated in experiments.