Effect of electromagnetic interference on coupled microstrip interconnects on lossy integrated circuit substrates

The author studies the time and frequency domain responses of a coupled microstrip line illuminated by a plane electromagnetic wave of arbitrary angle of incidence and polarization. Although the coupled microstrip on a lossy substrate provides an ideal preliminary model for the detailed investigation of externally induced electromagnetic noise in integrated circuits, currently there is no detailed study of this problem in the literature. A model which allows computation of the transmission line currents and voltages induced by the external field of arbitrary incidence at any point along the coupled microstrip line, terminated in passive load impedances, is developed. The effects of high substrate permittivity and loss tangent on the response of the microstrip to the incident field is investigated. The effect of wave polarization on wave coupling is studied against the angular orientation of the microstrip with respect to the direction of the incident wave