Spiral antennas have a wide range of applications in communications because they are circularly polarized with broadband characteristics with respect to both input impedance and radiation pattern. However, a spiral antenna that is conformal to a multilayered cylindrical media has not been reported in earlier studies. This thesis presents in depth analysis of such antennas using a full wave Method of Moments model. There are two crucial issues involved in such model: developing efficient spatial domain Green's function expressions, and then linking the Green's functions with the Method of Moments. An efficient algorithm to compute Dyadic Green's functions in stratified cylindrical media has been developed firstly. The convergences of the Green's functions have been greatly accelerated by employing a single asymptotic extraction in the spectral domain and the counterparts of those subtracted components in the spatial domain have been derived into compact closed-forms. On the other hand, two different methods to link the Green's functions and Method of Moments have been developed: look-up-tables and segment based approach. The look-up-table approach is efficient for modeling conformal antennas, while the segment based approach is especially suitable to model conformal antennas with a probe feed. The whole method has been validated by comparing computed results with those from CST or equivalent planar geometries. As a result, an efficient method to model antennas conformal to stratified cylindrical media incorporation with Method of Moments has been developed.

The idea of using textile materials for wearable antenna design has attracted much attention in the industry and academia because it is lightweight, flexible, and most importantly the textile antenna can be seamlessly integrated into garments. However, the wearable antennas which are made of flexible materials, such as textiles, have to face a common challenge: shape distortion. Unlike conventional antennas, which are usually fabricated by hard materials like metal and well protected within enclosures, wearable textile antennas will be integrated into clothes and operate directly on the human body surface. Therefore, it is very necessary to investigate the textile antenna performance under shape distortion conditions. This study focuses on the purely textile antenna design and the evaluation of the antenna performance under shape distortion conditions. Several types of antenna, such as coplanar waveguide fed (CPW) antenna and planar inverted-F antenna (PIF A), are fabricated in textile materials and investigated in 2.45 GHz wireless networking band. Moreover, the artificial magnetic conductor (AMC) structures and the microstrip antenna array are investigated in the latter part of this thesis. In this study, the textile antenna under test are not only bent, but also crumpled in different formats along the E-plane and H-plane. Both input impedance and radiation patterns are investigated, and the comparisons between simulation and measurement are analyzed.

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