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