Equivalent circuit of the near field communication antenna at low frequency based on composite grid method

To solve the conflict of the large scale and the small scale in the solution domains, the finite element composite grid method (CGM) is put forward in the equivalent circuit parameters extraction for the near-field communication(NFC) antenna.This method is to balance the calaulation efficiency and the accuracy.To avoid the breakdown of Maxwell equations at low frequency, the static field method is proposed for extracting the equivalent circuit parameters for the NFC antenna, considering the low value of the displacement current at low frequency.The distributed capacitance of the NFC antenna was usually got by the measurement method, the theoretical estimation method and the full wave analysis method before.Different from those methods, in this paper a novel method based on the definition of capacitance, is obtained by computing the capacitance of the coils relative to the ground.The results are coincident with the references, meanwhile, this method can also estimate the effects of the surroundings.Additionally, the comparison of the regular finite element method and the composite grid proves the practicability in electromagnetic 3-D model.