A Wireless Signal Transmission Scheme Between Full-metal Shells using Near-field Magnetic Flux

This paper reports a wireless transmission scheme that enables efficient signal communication through intact metallic enclosures without requiring any structural openings. Targeting aerospace applications where full-metal shells are essential for mechanical integrity, the method employs a pair of conformal coils tightly affixed to opposite sides of a thin metal wall. By leveraging the continuity of the magnetic field's normal component at the metal interface, the system achieves magnetic coupling across the barrier. Implemented using flexible printed circuit (FPC) technology, the prototype includes an impedance-matched interface for standard RF measurement. Experimental results on 2mm-thick stainless-steel plates and cylindrical shells demonstrate a transmission coefficient of approximately -20dB around 10MHz. The results confirm a reliable, non-invasive near-field communication across full-metal barriers, offering promising potential for structurally sealed wireless systems.