Split ring resonator and metamaterials at microwave regime, numerical analysis design, characterization

Recently, there has been a significant interest in Terahertz (THz) technology, primarily for its potential applications in detection of concealed objects as well as in medical imaging for non-invasive diagnostics. THz spectrum lies between the infrared and microwave spectra. The artificially structured frequency selective devices have been demonstrated to overcome a significant bottleneck in THz band. Among different Metamaterial configurations, Split Ring Resonator (SRR) can be used to create compact narrowband wave plates at THz frequencies, which is variable by changing the radius of ring, number of rings, material thickness, size of gaps. In this work we have designed double-ring SRR structures in four different sizes to achieve various resonance frequencies in the microwave band. For simplicity, SRR prototypes are designed in mm-size resulting resonance peaks at 3.7 GHz, 4.3 GHz, 5.9 GHz and 7.4 GHz for ring diameters of 4 mm, 3.6 mm, 3 mm and 2.6 mm, respectively. By calculating the capacitance and inductance of rings, the resonance frequency can be calculated mathematically. The fabricated split ring resonator prototypes are placed between two antennas and experimental characterization is done by a vector network analyzer in both of the finite-element simulation and experiments we have inspected Transmission (S21) and Reflection (S11) coefficients. We are characterizing samples with backside metallization. Simultaneous minimization of transmission and reflection at a certain frequency band, play a crucial role in obtaining high absorption coefficient. We employ the same design methodology for the design of THz absorbers.