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

Abstract

In order to achieve a significant reduction in volume over standard dielectric λsub/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 λo/4 cavity designs. Further reduction (94% of λo/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 <λo/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.