Design of a microstrip antenna with circular polarization

number: 
565
إنجليزية
Degree: 
Author: 
Hasan Kasim Abbas
Supervisor: 
Dr. Rafat T. Hussein
year: 
2001
Abstract:

The circular polarized microstrip antenna arrays are very important and effective for many communication systems when small size and low profile are required. Circular polarization is achieved by separating two degenerate orthogonal modes an annular ring microstrip patch antenna, by using an ear at the outer periphery. The analysis of such structure is performed using the network model, which uses the generalized transmission line model. The broadside TM|2 mode annular ring antenna structure is investigated to achieve circular polarization radiation over a wider frequency band (4.1% at -6dB axial ratio) and in the broadside direction (normal to the antenna aperture plane), good input impedance matching (50Q), good beam directivity (8.6dB) and higher efficiency (96%) than the structures reported so far in the literature. An annular ring structure is designed and its performance is evaluated for 3-GHz ^ central frequency. Linear, rectangular and triangular arrays were investigated to provide more beam directivity and power gain. The optimum distribution spacing is designed to minimize the mutual coupling effects. Feed network systems are implemented using exponential taper transformer to achieve broadband matching technique.