A rigorous analysis of the resonant frequency characteristics of an annular-ring conductor printed on a dielectric substrate backed by a ground plane is presented. The problem is cast into a set of vector dual integral equations by using vector Hankel transform (VHT). Galerkin's method is then applied to compute the resonant frequencies of both transverse magnetic modes (TM11 and TM12) of the microstrip antenna. The real part of the resonant frequency shift of the TMjj mode increases with increasing dielectric thickness in contrast to the TMI2 mode. While the TM11 mode has a high g, it is a poor radiating mode; the TM12 mode is more suitable for antenna applications. For a probe excitation the input impedance is obtained using single mode approximation for both the TM11 and TM12 modes. It is shown that the TM12 mode of the annular ring has a greater bandwidth than the TM11 mode.
ASJC Scopus subject areas
- Electrical and Electronic Engineering