Mutual coupling modeling of NFC antennas by using open-source CAD/FEM tools

Near Field Communication (NFC) antennas are not comparable to standard communication antennas used for traditional transmission services. The geometries are complex, narrow conductor cross-sections and long loops located close to materials sensitive to electromagnetic interaction, when integrated, make the application of analytical coupling formulations inapplicable, even when it comes down to non-linear relations forced by ferrite shielding. Commercial finite element (FEM) solvers are powerful, but they do not serve the needs of NFC applications due to complexity, inadequateness and code obscuration. An intensive open source code investigation has identified one alternative solver which is capable to deal with all NFC RFID related coupling effects one can imagine. Automated scripts, the tool-chain, and geometry macros have been developed for rapid prototyping of such. Amongst other open source tools listed, the ElmerFEM solver is the most promising solver for linear and non-linear quasi-static electro-magnetic (EM) NFC problems. The solver has a powerful interface and delivers results close to reality even when computational complexity is a trade of physical resolution and memory capacity of standard commercial workstations.