Time-domain simulation of trains of oscillation pulses in a Gunn diode system with a remote resonator

We present self-consistent time-domain simulation of trains of short oscillation pulses in a time-delay transmission-line circuit of active devices with a remote resonator for emerging radar applications. Inherent instability and essential nonlinearity of active devices makes many simulation tools inadequate for rigorous modeling of active systems with complicated dynamics of generated fields. Conventional software (e.g., SPICE) cannot easily cope with active distributed systems where the wave propagation between devices is an important part of system operation. A promising approach is the hybrid method that combines both the frequency-domain and the time-domain computations, though it suffers from various limitations (narrow-band approximation etc). For these reasons, the design of active structures is usually split in two stages dealing with either linear or nonlinear parts of the system. In this method, the attention is focused on passive components whose design is carried out in much detail. As a compromise, some assumptions have to be met in this approach such as the operation in the narrow band or in a given set of a few narrow bands, etc. In our work, we develop an alternative approach and focus attention on the nonlinear part of problem, while the linear part is chosen to be relatively simple. In this approach, the aim is the accurate self-consistent modeling of nonlinear effects through rigorous solutions of governing equations and, specifically, accurate time-domain simulations of nonlinear oscillations and non-conventional dynamics (chaos, pulses) emerging in various conditions. In addition, nonlinear power combining is investigated in a self-consistent manner.