Radiation characteristics of helical microstrip antennas

Due to the ability of microstrip antennas to conform to an underlying structure, they have a variety of applications with curved surface objects such as aircraft, missiles, satellites, etc. In many cases where the radius of curvature is large, a planar representation using an approximate theoretical approach is sufficient to analyze these antennas. However, for a small radius of curvature, more accurate and rigorous analysis is necessary. In this paper the analysis of a leaky-wave helical microstrip antenna is investigated. The equivalent magnetic current is created at the two sides of the helical structure by exciting the microstrip antenna with the TE/sub n0/ (n is odd) rather than the usual TEM excitation. For the helical structure a more complicated analysis is used to describe the dispersion characteristics using the boundary condition and point matching procedure at the interfaces. The characteristic equation is derived for a narrow magnetic tape on a dielectric coated cylinder. The extension of the developed technique to two parallel magnetic tapes is presented.