Coupling of antenna fields to planar microstrip transmission lines

The authors present a computer model to study the response of a lossy coupled microstrip interconnect illuminated by an electromagnetic field generated by an in the farfield zone. The model allows the computation of currents and voltages induced by the antenna fields of arbitrary angle of incidence and polarization at any point along the coupled microstrip line, which is terminated in passive loads at both ends. The effects of high substrate permittivity and loss tangent on the coupling of the antenna fields into the microstrip is investigated in detail. The author also presents a model for the coupling of the antenna fields to the microstrip when the line is placed in the near field zone of the antenna and the fields are highly nonuniform. The exact formulas for the wave coupling in this specific case contain complicated integrals which can not be evaluated analytically and numerical procedures are used to obtain the final results