Time-Domain Characterization of Nonlinear Electromagnetic Systems using the Koopman Operator

Wideband multi-carrier and multi-channel receivers are powerful communication system architectures for their high spectral efficiency, flexible bit-rates and data constellation format used by the dynamically selected sub-carriers. These systems, when augmented with MIMO (multiple input – multiple output) capabilities, further improve spectral efficiency and increase the number of users. However, the architectures that allow these performance benefits are also responsible for harmonic distortions, inter-channel crosstalk and inter-modulation products introduced by the nonlinear components of the receivers and nearby transmitters. The use of traditional analog linearization methods results in fairly complex and in many cases inadequate solutions. In addition, most time domain methods employed for electromagnetic modeling are either limited to linear systems or systems with known nonlinearities behavior. This paper introduces a time-domain method based on the concept of the Koopman Operator and describes its application to the characterization of dynamic systems with nonlinearities which are either unknown or difficult to mathematically describe.