Low-loss magneto-inductive waveguides

Radio-frequency experimental measurements of magnetically coupled chains of L-C resonators supporting magneto-inductive (MI) waves are presented. MI waveguides are constructed using printed circuit board (PCB) inductors and external capacitors. Methods for increasing the nearest-neighbour coupling and reducing the non-nearest neighbour coupling using double-sided PCBs are demonstrated. Conditions for low propagation loss are determined, and a method of approximate matching to 50 transmission lines is presented. Propagation losses of 0.12 dB per element and coupling losses of 0.4 dB are achieved, using elements with Q-factors of 110 at ≈150 MHz frequency. Simple recursive Fabry–Perot filters are demonstrated by inserting reflectors into the waveguide. 1.