Traveling Electromagnetic Waves on Linear Periodic Arrays of Small Lossless Penetrable Spheres
Rept. for Jan 2003-Jun 2004
AIR FORCE RESEARCH LAB HANSCOM AFB MA SENSORS DIRECTORATE
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Electromagnetic waves on infinite linear periodic arrays of lossless penetrable spheres can be conveniently analyzed using the source scattering-matrix framework and vector spherical wave functions. Our investigation of these arrays is motivated by the theoretical demonstration that a double negative DNG material can be formed by embedding an array of spherical particles in a background matrix. In this report we apply the spherical-wave source scattering-matrix approach to obtain an implicit transcendental equation for the propagation constants of the traveling waves that can be supported on infinite linear periodic arrays of lossless penetrable magnetodielectric spheres. Although a framework is presented for all orders of vector spherical waves, only the electric and magnetic dipole waves are included in the detailed analysis. The report focuses on determining the kd - Beta d diagrams for the traveling waves that can be supported. Backward waves and waves with low group velocity are shown to be supportable in narrow wavebands by arrays composed of spheres with appropriately chosen permittivity and permeability. Interestingly, for certain spheres and separations it is possible to have two or even three different dipolar traveling waves supported by the array.
- Radiofrequency Wave Propagation