Ultra-Wide Suppression Band of Surface Waves Using Periodic Microstrip-Based Structures

We propose the use of microstrip-based elements: spiral inductors and interdigital capacitors connected through transmission lines to provide a higher order wide surface wave suppression band. Design, modeling, and realization of optimum values for spiral inductors and interdigital capacitors are studied in detail. A grid of 77 2-D unit cells consisting of these designed interdigital capacitors and spiral inductors is manufactured and tested experimentally. The excitation of surface waves using different schemes are addressed and compared. Also, for comparative purposes, two reference cases of copper surface and dielectric backed copper are studied. The obtained results demonstrate the potential of this structure to be used as a very wideband suppressor.