Comparative analysis of the dispersion characteristics of a slotline and a microstrip line

This paper compares the dispersion characteristic of a slotline with that of a microstrip line. A full wave analysis of a slotline including the excitation source is presented. All kinds of modes are taken into account, including a bound mode, leaky modes, and a residual wave. The line is excited by a time-harmonic source of constant current connected across the slot of the line. The theoretically predicted results have been verified by experiments and by simulations in the CST Microwave Studio. A continuous behaviour is documented, rather than the step-like behaviour of waves propagating along the investigated lines as predicted by a pure eigenmode analysis.