Compact Dual-Band Dual-Sense Circularly Polarized Fragmental Patch Antenna Optimized by Improved Simulated-Annealing-Based Algorithm

This study presents a compact dual-band dual-sense circularly polarized (CP) fragmental patch antenna that advanced by an improved simulated-annealing-based optimization algorithm. This design replaces truncated corners of traditional truncated patch antennas with fragmental structures, generating dual-band dual-CP radiation with a small frequency ratio and a high front-to-back ratio. The proposed optimized framework tackles the multi-objective optimization problem through hierarchical optimization to achieve an optimal balance among various performance metrics. Furthermore, the simulated annealing is improved using a matrix-based dynamic step-size perturbation mechanism and a nested cyclic process, averting premature convergence and ensuring multifaceted objective enhancement. The measurement results reveal that the proposed antenna can operate with a small frequency ratio of 1.07, providing left-hand CP radiation from 4.99 to 5.02 GHz and right-hand CP radiation 5.34 to 5.41 GHz, respectively. This compact cost-efficient design demonstrates potential for diverse antenna applications.