Design of novel wideband electromagnetic band gap metamaterials and antenna elements utilizing oriented cobalt-substituted Z-Type barium hexaferrites.

摘要

In order to achieve a significant reduction in volume over standard dielectric lambda sub/4 cavity slot antenna designs, while concurrently maintaining usable gains >2-3 dB, realizable high permeability oriented cobalt-substituted Z-Type barium hexaferrite materials have been introduced through a modified aqueous synthesis technique both as magnetic substrates and as electromagnetic band gap (EBG) metamaterial ground planes. Significant volumetric reduction of antenna elements (92%) due to magnetic and dielectric loading has been achieved via tailoring the permittivity and permeability of the ferrite material through an orientation process over standard lambda0/4 cavity designs. Further reduction (94% of lambda0/4 cavity designs) is achieved via combining a realizable high permeability Co2Z hexaferrite (permittivity=16 permeability= 14) with a periodic array of metallic Sivenpiper Structures to create an EBG metamaterial. The thickness of the investigated EBG metamaterial is lambda0/125 at the lowest operation frequency. The bandwidth of these metamaterials is investigated in terms of realizable fabrication techniques, and is determined while biased from the phase of a reflected plane wave, as is common in literature, to be >50-75% of the L-Band. Unbiased designs with >50% bandwidth have also been reported. Gains of -2.5 to 2.5 dB have been achieved for both magnetic substrates and EBG ground planes, with a voltage standing wave ratio (VSWR) 2 indicating that these designs are practical for commercial and defense applications which call for low profile miniaturized antenna designs which do not suffer from reduced gain. Furthermore, these designs have been applied to conformal surfaces increasing the potential applications of these technologies.