Fabrication of Millimeter-Wave Electromagnetic Bandgap Crystals Using Microwave Dielectric Powders

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Electromagnetic bandgap (EBG) structures active in the 90–110 GHz region widely used by security imaging radar were created using different ceramics by a rapid prototyping method informed by finite difference time domain modeling. This solid free-forming method uses a high volatility solvent-based ceramic paste extruded through fine nozzles allowing ceramic powders to be assembled on a multiaxis building platform avoiding machining, etching, or the alignment of loose rods and created to designs downloaded directly from a computer file. Lattices were made from two high dielectric constant ceramics: La(Mg0.5, Ti0.5)O3 and (Zr0.8, Sn0.2)TiO4 and compared with those of Al2O3 demonstrating three EBG structures with different dimensions and dielectric constants but with the same bandgap. The effects of manufacturing tolerances on bandgap frequency are investigated by simulation.