Aharonov-Bohm effect Barium hexaferrite Bateman construction Harvesting History of engineering & technology Maxwell theory Poynting Multivector X-ray diffraction constraint equations correlation coefficient dispersion diagram effective power density electric-magnetic duality symmetry electrodynamic structure electrodynamics electromagnetic duality symmetry electromagnetic knots electromagnetic polarization evolutionary equations finite element analysis geometric algebra glide symmetry ground high speed system harmonics helicity high-order coupling hopfion hysteresis interval thresholding method low-power applications