Coupling-based turns distribution for planar spiral coil antennas in near field magnetic induction links

Abstract

This paper describes a numerical study of a coupling-based turn-distribution approach to achieving good transmission performance in near field magnetic inductive links using low Q-factor coil antennas. Coil antenna turns are distributed to match an upper reference coupling level, leading to a stronger axial H-field, with a low margin of Q-factor increment from a baseline minimum. Numerical results demonstrate improved transmission efficiency performance relative to a minimal Q-factor coil antenna when the modified antenna is employed in a symmetric bi-directional inductive link. This approach to increasing transmission efficiency indicates prospects for extending the utility of low Q-factor HF-RFID interrogator antennas to include wireless power delivery applications.