| Microstrip antennas have become increasingly attractive in many modern communication systems. The conventional microstrip antennas, which commonly use isotropic dielectric substrates, exhibit several unwanted characteristics. The objective of the present research is to explore possibilities to improve microstrip antenna performance by using anisotropic dielectrics. Case studies have been performed for selected single/multilayered microstrip geometries including: (1) Printed dipole antenna covered by a biaxial anisotropic conducting layer, (2) printed narrow slot antenna on a grounded uniaxial anisotropic conducting substrate, and (3) printed dipole antenna in a multilayer configuration involving uniaxial conducting and isotropic substrate. As an essential first step, we develop spectral-domain Green's functions that account for multilayer arrangements consisting of biaxial or uniaxial anisotropic dielectric substrates together with standard isotropic dielectric substrates. Using these Green's functions, rigorous analyses are formulated to model various antenna characteristics, such as resonant frequency, radiation efficiency, and radiation pattern. Numerical data for various design parameters are generated for selected antenna geometries to examine their performance improvement and practicality. |
