This work investigates numerically four planar microcoil models (square, circular, rectangular and TLMR (Transmission Line Monolithic Resonator)) in terms of magnetic parameters, quality factor, biocompatibility, and harmlessness. These Planar microcoil models were simulated as the active part of a radio frequency (RF) implantable receiver antenna dedicated to the Nuclear Magnetic Resonance (NMR) Spectroscopy. The novelty provided by this approach is the comparative study of these different shapes by a hybrid method combining EM (Electromagnetic) simulation and RLC equivalent model calculated through implemented FEM (Finite Element Method). The second part of the realized work is the implantation of the best microcoils in a numerical phantom. Then, assuring the harmlessness of the implantation of such microcoils for NMR investigations by predictive simulation in numerical head model.