Modeling and optimization of signal to noise ratio in periodically time-varying electromagnetic systems

Periodically time-varying electromagnetic structures have been of recent interest for their ability to realize exotic behaviors not found in linear time-invariant (LTI) systems, such as nonreciprocity, parametric amplification, and frequency conversion. A family of methods have been reported by several research groups for frequency-domain modeling and analysis of periodically time-varying electromagnetic problems. All these methods have their roots in well-known methods for time-varying circuit analysis, such as conversion matrices, which generalize standard network quantities such as impedance, admittance, scattering parameters, or transmission parameters to model conversion between harmonic frequencies (Maas, 2003). This frequency conversion is hybridized with full-wave electromagnetic analysis of the LTI parts of the problem and the entire system may be represented by a multifrequency matrix in which each physical port is represented by multiple virtual ports, one at each harmonic.