Antenna Miniaturization Using Magnetic-Photonic and Degenerate Band-Edge Crystals

Engineered materials, such as new composites and electromagnetic bandgap and periodic structures have been of strong interest in recent years, due to their extraordinary and unique electromagnetic behaviors. This paper discusses how modified materials, inductive/capacitive lumped loads, and magnetic materials/crystals are impacting antenna miniaturization and performance improvements (e.g., bandwidth and gain reduction, multi-functionality, etc.). Dielectric design and texturing for impedance matching has led to significant size reduction and higher-bandwidth low-frequency antennas, for example. The recently introduced magnetic-photonic crystals (MPCs) and double band-edge (DBE) materials, displaying spectral non-reciprocity, are also discussed. Studies of these crystals demonstrated that magnetic-photonic crystals exhibit the interesting phenomena of (a) drastic slowing down of the incoming wave, coupled with (b) significant amplitude growth, while (c) maintaining minimal reflection at the interface with free space. The phenomena are associated with diverging frozen modes that occur around the stationary inflection points within the band diagram. Taking advantage of the frozen-mode phenomena, we demonstrate that individual antenna elements and linear or volumetric arrays embedded within the magnetic-photonic crystal and double band-edge structures allow for antenna sensitivity and gain enhancements.