Analog of electromagnetically induced transparency from electric dipole and quadrupole excitation with a Reuleaux triangle split-ring resonator

We simulate, measure, and analyze an electromagnetically induced transparency-like (EIT-like) metamaterial with a unit cell composed of a Reuleaux triangle split-ring resonator (RT-SRR) and a Y-type strip (YS). The transparency peak of the EIT-like metamaterial is located at 12.54 GHz, and the transmission coefficient is 91%. The electric field distributions indicate that the RT-SRR plays the role of the bright mode, and the YS plays the role of the dark mode. The coupling between the bright and dark modes leads to the EIT-like phenomenon. The surface current distributions and the calculated results for the radiated power of the electric multipoles are used to analyze the physical mechanism behind the transparency peak, which can be understood in terms of the electric dipole interacting with the electric quadrupole. As the polarization angle increases, the transmission coefficient of the transparency peak decreases, indicating polarization sensitivity. When the YS is rotated around the center and the RT-SRR is kept fixed, the EIT-like phenomenon appears and disappears. Therefore, the proposed metamaterial has potential applications in detectors and switches. The experimental results are well-matched with the simulation results.