Near-field coupling model of a non-uniform external electromagnetic field to a printed circuit board trace

The electromagnetic (EM) coupling on a printed circuit board (PCB) is a very important concern when investigating electromagnetic interference (EMI) issues. This paper presents an approach to model a non-uniform external EM radiation to a single trace on a PCB. The approach is totally analytic and based on the quasi-TEM (Transverse ElectroMagnetic) transmission line (TL) model taking into account the effect of the effective relative permittivity ε_reff of the PCB trace surrounding medium. The trace terminal responses are computed referring to three coupling formulations. Analytic solutions, with comparison to numerical results, allow us to validate the proposed model.