Design of a wideband Vivaldi antenna array and performance enhancement of small Vivaldi arrays using baffles.

摘要

The motivation for the first aspect of this work was the need for a wideband antenna array to be used with the accumulation radar. We chose the Vivaldi antenna because of its many advantages. A thorough design study was conducted in order to determine the optimal Vivaldi element dimensions to be used in the array. Two electromagnetic software packages, called Ansoft HFSS and CST Microwave Studio, were used for all the simulations in this study. The initial element design was first optimized in an infinite array, and this optimized Vivaldi element design was then used to simulate finite arrays ranging in size from 7 to 12 elements. The final 12 element array satisfied the design requirements for input return loss, frequency bandwidth, gain, sidelobe levels and size of the array. This 12 element array was used with the accumulation radar in field tests conducted in Greenland in July 2005.; The second part of this thesis deals with the improvement of wideband input return loss of small Vivaldi arrays by adding metal walls called "baffles" at the edges of the arrays. The results presented in this thesis show that small Vivaldi arrays with optimal-sized baffles exhibit return loss characteristics similar to larger arrays of the same elements. The radiation patterns of the arrays considered were also not affected much by the addition of baffles. Hence, we concluded that baffles can be added to improve the input return loss performance of small Vivaldi arrays without any degradation in the array radiation patterns. (Abstract shortened by UMI.)