Efficient time-domain analysis of highly dispersive linear and non-linear metamaterial waveguide and antenna structures operated in the impulse-regime

Abstract

In this paper, a numerical method has been proposed for the analysis of highlydispersive linear and non-linear metamaterial structures. Initially, pulse propagation along non-linear composite right/left-handed transmission line (CRLH TL) has been carefully studied. For this purpose, a dispersive CRLH line has been loaded with hyper abrupt diodes to achieve non-linearity. The characteristic impedance and propagation constant of each unit cell of the CRLH TL is then varied at each time-step, and the nonuniform line is analyzed. A novel interpolation scheme, based on the smooth behaviour of the propagation constant with small variations of the shunt capacitor has been proposed. This scheme has provided an 80% reduction of the computational cost maintaining high accuracy. A general example which combines dispersion and nonlinearity has finally been presented, validated and discussed. Secondly, the impulseregime radiation of a leaky-wave antenna has been analyzed and employed to describe a real-time spectrogram analyzer (RTSA). A calibration method for the system, which takes into account the directivity variation of the antenna with frequency, has been introduced. Numerical results have shown that the proposed technique provides an extremely fast and accurate tool to characterize leaky-wave based RTSA systems.