On the study of nonlinear left-handed metamaterials for harmonic and subharmonic generation

Nonlinear transmission lines (NL-TL) are used extensively for harmonic generation and pulse shaping. In this paper, we investigate the theoretical behaviours of harmonic and subharmonic generation based on left-handed (LH) NL-TL. The nonlinear elements in our investigation are back-to-back varactors, resulting in the absence of a biasing circuit. The nonlinear left- handed unit cell consists of series varactors and shunt inductors. The simulation results show that the frequency tripler can achieve 25.5 % conversion efficiency when driven by a 20 dBm sinusoidal source at 0.8 GHz. The 3-dB operation bandwidth of the tripler is 180 MHz. In the case of the frequency divider 96.5 % conversion efficiency for f₀/2, where f₀ is 2.2 GHz, can be achieved. Both circuits examined have the same Bragg cut-off frequency, f_B=261.7 MHz. The goal of this research is to acquire useful information on the performance of LH transmission lines and their advantages (if any) compared to conventional right-handed (RH) ones when it comes to circuit applications.