1. Introduction
Microstrip antenna has gain popularity because of their small size and light weight. However a limitation of microstrip antenna is the narrow bandwidth of the basic element. The bandwidth of a basic patch element is usually 1. 3%. The bandwidth of the antenna is defined [1] as the range of frequencies, over which the performance of the antenna with respect to some characteristic conforms to a specific standard. The bandwidth of the antenna depends on patch shape, resonant frequency, dielectric constant and the thickness of the substrate.