Thin-film magneto-inductive cables

R R A Syms (1) , L Solymar (1) , I R Young (1) , T Floume (1)

1 Optical and Semiconductor Devices Group

Magneto-inductive cables for low (ca 100 MHz) radio frequencies are demonstrated in thin-film form. 20 cm long resonant elements are formed using double-sided patterning of copper-clad polyimide, based on single-turn inductors and parallel plate capacitors that use the substrate as an interlayer dielectric. Continuous cables are formed by overlaying elements, in an arrangement that allows a high, positive coupling coefficient (κ > 0.6) to be achieved despite the use of a planar geometry. Equivalent circuit parameters are extracted from experiments on integrated coupling transducers, and propagation characteristics are compared with simple theory. Low propagation loss (4 dB/m at 55 MHz, falling to 2.3 dB/m at 130 MHz) is demonstrated near the operating frequencies of magnetic resonance imaging, for a potential application as patient-safe cable in internal imaging.

Mots clés: KEYWORDS Metamaterial; periodic structure; magneto-inductive wave PACS numbers 41.20.-q Applied classical electromagnetism 81.05.Zx New materials: theory; design and fabrication 84.30.Bv Circuit theory

R R A Syms, L Solymar, I R Young, T Floume. Thin-film magneto-inductive cables. Journal of Physics D: Applied Physics, 2010, 43 (5), pp.55102. ⟨10.1088/0022-3727/43/5/055102⟩. ⟨hal-00569750⟩