Optimization of A Microstrip Directional Coupler with High Performance Using Evolution Strategy

In this paper, an optimal design of novel microstrip directional coupler with a grooved housing for high directivity characteristic is presented. It will be shown that the high directivity of the microstrip coupler can be achieved simply by attaching an optimized housing structure over the microstrip, which is much easier to fabricate than other conventional ones. The dimensions of the proposed structure are optimized by using (1+1) evolution strategy (ES) combined with deterministic algorithm. To improve the optimization results, efficient optimization procedures suitable for the model are proposed. From the optimization results, it is figured out that the proposed structure shows an improved directivity. The optimized result is verified by full wave analysis at the center frequency of 850MHz.