Objective Relaxation Algorithm for Reliable Simulation-Driven Size Reduction of Antenna Structures

This letter investigates reliable size reduction of antennas through electromagnetic-driven optimization. It is demonstrated that conventional formulation of the design task by direct footprint miniaturization with imposing constraints on electrical performance parameters may not lead to optimum results. The reason is that - in a typical antenna structure - only a few geometry parameters explicitly determine the antenna footprint, and therefore sensitivity of antenna size to other parameters is zero. At the same time, finding the genuine optimum requires adjustment of all parameters as the optimum is determined by the tradeoff between the size and other figures of merit such as reflection characteristic. Here, an alternative design methodology is proposed that involves relaxation between size reduction and matching improvement. Our methodology is demonstrated using two examples of ultrawideband antenna structures. It is superior over the conventional approach in terms of the optimized antenna size achieved. Experimental validation of the results is also provided.