Analysis of microstrip wraparound antennas using dyadic Green´s functions

The radiation pattern of microstrip wraparound antennas was obtained here using a theory based on dyadic Green´s functions for concentric-cylindrical layered media. The dielectric layer that is usually neglected as a first-order approximation was considered here. An asymptotic expression for the dyadic Green´s function that takes into account only the space wave is first obtained. Radiation patterns for various radii, permittivities, and thicknesses of the dielectric layer of a microstrip wraparound antenna were obtained using as a source a uniform annular magnetic current obtained by means of a cavity model with conducting magnetic walls. The calculated values of the percent pattern coverage decreases as the thickness and the permittivity of the dielectric layer increase. The influence of the dielectric layer is more pronounced for radiation direction near that of the axis of the cylindrical surface. It is also shown that the radiation patterns at a frequency of 2.0 GHz are not much dependent on the diameter of the antenna for values from 3 to 120 in.