Analysis by Asymptotic Boundary Conditions of Strip-Grated Dielectric Pipe over Dielectric Rod with Wide Total Band-Gap as Multi-Frequency Cylindrical Leaky-Wave Antennas

In this paper, the method of classical vector potential analysis along with the asymptotic strips boundary conditions (ASBC) is used to treat conducting strip grated dielectric pipes wrapped over core dielectric cylindrical rods. By virtue of the periodically-textured surface, this structure is able to exhibit plasmonic behaviors that facilitate strong surface field localization and wave propagation, thereby offering itself as cylindrical surface-wave waveguides or antennas. It can also be configured to exhibit electromagnetic band-gap (EBG) properties, yielding what is known as cylindrical EBG structures. As opposed to a typical counterpart whose core rod is instead conducting, the core dielectric is herein demonstrated to be vital in realizing wide total band-gaps in which neither slow surface nor fast space waves exist, something that the conducting core rod version is incapable of, being only able to offer surface-wave band-gaps, as do many others in the literature that have neglected the suppression of fast space waves as well. By coaxially connecting various such rod structures, each with its own distinct total band-gap, multi-frequency, multi-functional cylindrical antennas with mitigated inter-band interference even under simultaneous operations can be achieved when the pass-band of any one rod (in which its operating frequency lies) falls within the total band-gaps of all others, as herein investigated. Manufactured prototypes are also measured, yielding experimental results that agree well with theoretical predictions.