A compact ultra-wideband self-complementary antenna with optimal topology and substrate

The focus in this paper is to design a compact ultra-wideband self-complementary antenna (SCA) optimized for bandwidth constrained by size. The concept of frequency independent self-complementary geometries is applied to achieve the highest bandwidth possible, and a genetic algorithm (GA) optimization method is used to provide the optimal planar antenna topology and substrate design in an available finite space. An FDTD technique is used to fully analyze the complex antenna structures. It is demonstrated that a GA-optimized SCA can provide a wide bandwidth ratio of about 1:5 which occupies an area as small as λ/4×λ/4 at the lowest frequency. An equally spaced alternate-leaves SCA on an optimized meta-substrate is also proposed that provides ultra-wideband bandwidth characteristics (bandwidth ratio 1:8) with as small dimensions as λ/3×λ/3.