Characterization of electromagnetic band-gaps composed of multiple periodic tripods with interconnecting vias: concept, analysis, and design

This paper examines the performance of an electromagnetic band-gap structure (also known as photonic band-gap). The structure is purely metallic and infinitely periodic in two dimensions with a finite periodicity in the third dimension. An effective band-gap exists when within a certain frequency range, the reflection is 100% for all angles of incidence and all polarizations. The performance of the structure is explained from a physical point of view by isolating the effects of each parameter of the structure. Cascading two periodic arrays with a very small separation distance gives a capacitance effect for the overlap region. The capacitance is shown to control the lower edge of the band-gap. Cascading more closely coupled periodic arrays gives a rejection band, with the separation controlling the upper edge of the band. An effective band-gap is shown to exist when different layers are connected with vias. The structure examined in this paper has an effective band-gap from 30 GHz to 100 GHz. The calculations are performed using the method of moments (MoM) to solve an integral equation with the periodic Green's function as its kernel. The computations are extensive because they involve double infinite summations. A customized Z-matrix interpolation scheme is, therefore, used to speed the total calculation time, without sacrificing accuracy.