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.