Coupled microstriplines with ENG metamaterial loading: physical concepts, design formulas, and numerical simulations

In this contribution, we present the analysis and design of coupled microstriplines loaded with proper epsilon negative (ENG) metamaterial slabs. The behavior of the proposed component is at first analyzed through a heuristic approach. The main result of this investigation is that, depending on the orientation of the ENG slab, it is possible to achieve either higher or very reduced coupled values. A conformal mapping technique is, then, applied in order to derive closed analytical forms for the effective permittivity and the mutual coupling as a function of the geometrical and electrical parameters for the different orientations of the ENG slab. Such formulas are used to design different components, such as power dividers, decoupled lines, coupled lines with anomalous values of coupling, etc. Finally, the electromagnetic behavior of these components expected from the analytical design has been compared to the one obtained through full-wave numerical simulations, showing a very good agreement.