The Design and Optimization of Radiating Antennas for the Diamond Nitrogen-Vacancy Color Center

The diamond nitrogen-vacancy (NV) color center, with its excellent spin and coherence properties, has gradually become a novel sensitive component for magnetic field and current sensing. Research on the applications of the NV center in diamond requires optical pumping magnetic resonance (ODMR) technology to manipulate the electron spin states, where the uniformity and conversion efficiency of the microwave radiation structure are critical to sensor performance. In existing antennas, copper straight-wire radiation is uneven and results in significant energy loss. Although loop antennas provide relatively stable and uniform magnetic fields at the center of the loop, they suffer from excessive return loss and insufficient radiation intensity at the desired resonance points. To address these issues, this paper conducts electromagnetic simulations and structural optimization of a microstrip patch loop antenna. Using HFSS simulation, the relationship between key design parameters and radiation performance was analyzed, leading to an antenna structure that meets the spin resonance requirements of NV centers. During the optimization process, the effect of the ground plane length on antenna performance was studied, effectively improving radiation efficiency and uniformity. These improvements are expected to significantly enhance the performance of NV center-based sensors.