This paper presents a new mathematical approach to modeling EM wave coupling noise so that it can be easily integrated into chip-level noise analysis tools. The new method employs Chebyshev approximation technique to model the distributed sources arising in the Telegrapher’s equations due to EM wave coupling. A uniform plane wave illumination metric is provided to determine the order of approximation. Closed-form formulas for the noise transfer functions’ moments are derived. By utilizing the formulated moments, reduced order models can be efficiently obtained to generate the induced noise caused by EM wave illumination. The accuracy of the proposed method is verified by Hspice simulation.