Improved Fractal Microstrip Antennas

Abstract

Improved microstrip antennas are designed and analyzed for their applications in several wireless communications. Performance enhancements of these antennas are achieved here by fractal-based modifications. A thorough literature survey is carried out on different fractal structures, their applications to various antenna and array designs. newlineAt first, a triadic Cantor fractal concept is applied to a linear wire antenna array. Comparatively better performance parameters are achieved in this fractal array with a reduced number of array elements than the conventional array. An investigation is carried out on the performance of Cantor array for both strip dipole and V-dipole wire linear array in UHF band communication. Later, owing to the limitations in the design and performances of these dipole arrays, the rest of the research work is focused on studying the effect of fractal concept on microstrip patch antennas (MPAs). newlineThe design problem is divided into two groups. In the first group, improved MPAs are designed with fractal-based modified patch geometries. The radiating patch of the MPA is modified based on the Sierpinski Carpet fractal structure. This modification helps the MPA to achieve multi-band properties for the applications in WLAN and other microwave imaging wireless communications. Different feeding techniques are also examined for the same MPAs, to discover the best among them for the implementation of the fractal. newlineIn the second group, the fractal concept is applied to the defected ground structures (DGS) for performance enhancement of the MPAs. At first, the multi-functional properties of DGS are validated with a single patch and its array for ISM band wireless communication. Later, the fractal concept is merged with DGS to gain maximum benefit out of it. The ground planes of the MPAs are defected precisely under the patch and under the feed line, to achieve patch size reduction and higher-order harmonics suppression, respectively. The ground plane of a microstrip antenna array has also defected bet