US Patent 8400024 Wireless energy transfer across variable distances

Described herein are embodiments of transferring electromagnetic energy that includes a first electromagnetic resonator receiving energy from an external power supply, said first resonator having a resonant frequency ω1, an intrinsic loss rate Γ1, and a first Q-factor Q1=ω1L1/(R1ohm+R1rad), generating an oscillating near field region, a second electromagnetic resonator being positioned at variable distances from said first resonator and not electrically wired to said first resonator, said second resonator having a resonant frequency ω2, an intrinsic loss rate Γ2, and a second Q-factor Q2=ω2L2/(R2ohm+R2rad). Electromagnetic energy may be transferred from said first resonator to said second resonator over a variable distance D that may be within the near-field region of the first resonator structure, and wherein R1ohm>R1rad, and R2ohm>R2rad.