Coil design. (a) Unrolled view of the design. Red and blue rectangles represent the 4 channel 1H and 3 channel 13C arrays, respectively. Locations of decoupling inductances are marked by green boxes labelled TD, whereas locations of the LCC traps are marked by violet LCC-boxes. (b) 3D view of the RF coil with respective radii. (c) Equivalent circuit of the central 13C element, incorporating balun and matching network, coil capacitors, decoupling inductances, and LCC trap circuits. Neighbouring coil elements are indicated in light grey. (d) Final coil set-up with 3D printed housing, and cable strands.