Design and Optimization of Microwave Triangular Meta-material Resonators in Coplanar Configuration

Metamaterial (MM) structures exhibit phase and group velocities having opposite sign and negative effective permittivities, making them good candidates for novel applications in microwave sub-systems. Several analytical and experimental results are available concerning the shape optimization of resonating MM configurations. In this paper, a Complementary Sierpinksi Triangular Resonator (C-TSR) in coplanar waveguide (CPW) has been studied for C and X Band applications. The peculiarity of the triangular structure to exhibit multiple resonances is proposed for dual and three-band purposes, to obtain efficient unit cells for high performance microwave tunable oscillators. The MM nature of the resonators has been studied deriving the effective dielectric and magnetic permittivity by means of the Y- and Z- electrical parameters. Single and back-to-back triangles, even including the presence of inner small triangular resonators, have been simulated, optimizing the performances of the notch response in terms of quality factor Q and impedance matching. As a result, a proper shape and number of inner triangles can change the frequency of resonance of the entire structure. Q-values up to 10000 have been predicted, and an isolation better than 30 dB between the resonance peaks has been evaluated.