Nested Dual-Coil Antenna for Mobile NFC Coupling

The patent implements a nested coil structure where a small coil (first coil) is positioned inside or adjacent to a larger coil (second coil). The small coil couples to the mobile device while the larger coil extends the effective coupling area. This nesting arrangement allows the system to maintain compact form factor while achieving enhanced coupling area through the outer coil's larger footprint.

The patent transitions from a single-coil configuration to a dual-coil system operating at different spatial scales. The first coil operates at the scale of the mobile device, while the second coil operates at a larger spatial scale, effectively adding a dimensional layer to the coupling geometry. This multi-scale approach enables simultaneous compatibility with small mobile devices and extended coupling range.

The nested dual-coil structure allows the system to maintain the simplicity and low cost of small coil manufacturing while adding a larger outer coil that improves coupling efficiency. The inner small coil preserves compatibility with mobile device form factors and manufacturing processes, while the outer large coil enhances energy transfer efficiency to reader devices through its larger coupling area.

The patent creates a composite antenna system combining two coils with different electrical and geometric properties. The first coil (smaller, higher impedance) and second coil (larger, lower impedance) work together as a composite structure, where each coil contributes its strengths: the small coil maintains compactness and the large coil provides efficient coupling, achieving overall superior performance to either coil alone.

The nested coil configuration where a small inner coil is positioned within or adjacent to a larger outer coil creates a hierarchical coupling structure. The small inner coil maintains compact device integration, while the larger outer coil provides a broader coupling zone that increases alignment tolerance with reader devices, reducing the need for precise positioning.

The antenna system is segmented into two functional coils with different spatial footprints. The first coil handles compact integration with the mobile device, while the second coil provides extended spatial coverage for coupling. This segmentation allows each coil to optimize for its specific function, with the larger coil compensating for alignment variations.