Quasi-TEM Rectangular Waveguides with Frequency Selective Surface Walls: Part II-Physical Mechanism

The physical mechanism of quasi-TEM (transverse electromagnetic) waveguides with frequency selective surface (FSS) walls is established on the basis of an equivalent magnetic current technique in this paper. The equivalent magnetic current distributions in the slots of dielectric surfaces with dipole-FSS walls and dielectric surface of bare-slab, as well as hexagonal crystal FSS walls, are presented and discussed. This study shows that the electromagnetic fields in waveguide are mainly radiated from the concurrent magnetic current bands in longitudinal slots. The relationship between the uniformity of electromagnetic fields and the phase variation of longitudinal magnetic currents is discussed. The electrical properties and mechanism of quasi-TEM rectangular waveguides with slotlines are also investigated to confirm the proposed mechanism. Three categories of periodic structure, which are potentially useful as artificial magnetic conductor, are investigated, and the required conditions to realize quasi-TEM mode in rectangular waveguide are proposed. Copyright (c) 2013 John Wiley & Sons, Ltd.