A high-directivity microstrip patch antenna design by using genetic algorithm optimization

Abstract

A high-directivity patch antenna with broadside directivity is attractive, since a narrow beam can be obtained without the need of using an array of antennas. Therefore, the solution becomes simpler as there is no need for a complicated feeding network. In this sense, this paper presents a novel patch antenna design with high directivity in the broadside direction by using genetic algorithms (GA). The proposed GA method divides the overall patch area into different cells taking into account that cells have a small overlap area between them. This avoids optimized geometries where cells have only an infinitesimal connection. Therefore, the proposed method is robust for manufacturing. The antenna operates in a higher-order mode at 4.12 GHz and the geometry fits inside a patch of 40 mm × 40 mm on a substrate with a relative permittivity of 3.38 and a thickness of 1.52 mm resulting in a directivity of 10.5 dBi. The specialty of this design is the use of GA to select the optimized shape and the feeding position instead of a known shape and a fixed feeding position. The antenna has been fabricated and the simulation results are in good agreement with the measurements. This results in a simpler design of a single high-directivity patch, which can substitute an array of two elements operating in the fundamental mode.