The Influence of Asymmetry on the Appearance of Combinational Pulses in Transmission Lines with Inhomogeneous Dielectric Filling

The article presents the results of analyzing the influence of asymmetry on the voltage waveforms at the output of transmission lines (TL) with inhomogeneous dielectric filling. It was identified that asymmetry in the cross-section and/or boundary conditions leads to the appearance of combinational pulses. Their delays do not correspond to the per-unit-length delays of the modes propagating in the TL, but consist of their combinations. An analysis of four coupled TLs with both symmetric and asymmetric cross-sections was conducted in two cases of boundary condition implementation: with symmetry (matched loads) and asymmetry (open-circuited and short-circuited terminations at the ends of the passive conductor) of terminal loads. Additionally, we analyzed a 4-conductor TL with symmetry of the cross-section and asymmetry of loads in the form of open circuit-short circuit on the second and fourth conductors, as well as open circuit-short circuit on all passive conductors. Quasi-static simulation of these TLs revealed that combinational pulses can even occur in initially symmetric TLs. Depending on the variant of load asymmetry implementation, combinational pulses can appear within a group of reflected pulses (the variant of open circuit and short circuit on passive conductors) or between the primary pulses (the variant of connecting conductors with bridges in a meander line).