Analysis of Microstrip Patch Antenna Arrays with Ebg Structures and Fss

3.1 INTRODUCTION This chapter explains the methods to improve the directivity, and bandwidth of microstrip antenna array, using EBG structures and the FSS as a superstrate layer. This chapter also details the concept, principles of operation and the geometries of the unit cell of various EBG structures used, along with the microstrip antenna array configuration. Using the Multiconductor Transmission-Line (MTL) theory, the dispersion equations for the mushroom-like EBG and fork-like EBG, are obtained theoretically and verified. In addition to the equivalent circuit of the mushroom-like and fork-like EBG structures, the dispersion diagram is obtained theoretically from the dispersion equation. In this thesis, two approaches are proposed for improving the performance of the microstrip antenna array. In the first method, the EBG structures are placed on either side of the feedline of the microstrip antenna array. The optimal position of the EBG structures on both sides of the feedline is calculated using a parametric study. In the second method, the FSS is placed as a superstrate layer in the aperture coupled microstrip antenna array. The parametric study is done, for identifying the optimal height at which the FSS can be placed from the radiating patch. The parametric studies were performed using the CST microwave studio. In this research, the various EBG structures have been incorporated along with the