Figure 4 Microstrip line equivalent circuit of etched TL-shaped
DMS structure
In Figure 4, C 1, C 2,C 3, C 4 andC 9, C 10,C 11, C 12 are the
equivalent capacitances between the transmission line and the reference
ground, C 5, C 6,C 7, C 8 are the coupling
capacitances between the two coupled transmission lines,L 1, L 2,L 3 and L 4,L 5, L 6 are the inductances
of the transmission line, and L m1,L m2, and L m3 are the
coupled inductances. Structure a and structure b are equivalent circuit
structures of the TL-shaped DMS. Structures c and d must be designed
because the DMS structure changes the current distribution on the
microstrip line, which affects the reference ground. According to the
analysis of the equivalent circuit, the etching DMS can change the ratio
of the capacitive coupling and the inductive coupling between the
coupled microstrip lines, that is, \(C_{m}/C_{T}\) and \(L_{m}/L_{T}\)in Equation (1), thereby reducing the far-end crosstalk\(V_{\text{fext}}\).
Based on the above analysis, an excellent DMS structure design can have
a good ability to suppress far-end crosstalk by clever design,
therefore, the TL-shaped DMS is etched on the microstrip line B. The
specific structure model is shown in Figure 5. Figures 5(a) and (b) show
the top view and left view of the model.