Design and Optimization of Broadband Matching Networks for Widely Steerable Phased Array Radar Systems

Abstract

The use of phased arrays have become prevalent in radar systems for military and weather applications due to their planar configuration and ability of electronic steering. However, mutual coupling between surrounding antenna elements causes degradation in performance at wide scan angles and broad bandwidth. This mutual coupling creates impedance mismatches at the element-level. A matching network can be used to correct this, but broadband matching networks that consider scan angle have not been explored. This work introduces a novel optimization method for designing matching networks. This method seeks to improve performance for wide-scanning broadband phased arrays, especially NASA’s Ecological Synthetic Aperture Radar (EcoSAR). The fabricated static matching network achieves a 78% reduction in the optimizer objective function and provides a 10 dB match for the majority of the scanning range of -40° to 40° at a fractional bandwidth of 28.7%. This method is also used to design a tunable matching network that achieves a measured 99.95% reduction in the optimizer objective function and provides a 15 dB match across frequency and scanning range for the EcoSAR array using frequency bins. This novel design method shows great promise for improving performance for future wide-scanning broadband phased array systems.