Rapid Redesign and Bandwidth/Size Tradeoffs for Compact Wideband Circular Polarization Antennas Using Inverse Surrogates and Fast EM-Based Parameter Tuning

Design of compact wideband circularly polarized (CP) antennas is challenging due to the necessity of simultaneous handling of several characteristics [reflection, axial ratio (AR), and gain] while maintaining a small size of the structure. Antenna redesign for various operating bands is clearly more difficult yet practically important because intentional reduction of the bandwidth (e.g., by moving the lower edge of the operating band up in frequency) may lead to a considerable size reduction, which can be beneficial for specific application areas. This article proposes a rigorous approach to rapid redesign of miniaturized CP antennas involving inverse surrogate models and fast electromagnetic (EM)-based parameter tuning. Our methodology allows for a precise control of the lower operating frequency of the CP antenna (both in terms of the impedance and AR bandwidth) and accomplishing the geometry parameter scaling at an extremely low cost of a few EM analyses of the structure at hand. Our methodology is demonstrated by redesigning a compact wide slot CP antenna in the range of 3.2-5.8 GHz. The proposed approach can be used for fast rendering of the bandwidth/size tradeoffs (the footprints obtained for the verification structure range from 783 to 482 mm 2 ), thus determining the most suitable designs for particular applications. The numerical findings are experimentally validated.