(d)
Figure 7 EM fields lines and magnitudes of the coupled microstrip lines with and without TL-shaped DMS: (a) electrical field lines and magnitudes of the coupled microstrip lines without TL-shaped DMS, (b) electrical field lines and magnitudes of the coupled microstrip lines with TL-shaped DMS, (c) magnetic field lines and magnitudes of the coupled microstrip lines without TL-shaped DMS, (d) magnetic field lines and magnitudes of the coupled microstrip lines with TL-shaped DMS
Compared with the simulation results of EM in Figure 7, the electric field and magnetic field intensity in the space near the microstrip line etched with TL-shaped DMS structure are decreased. It can be concluded that the etching of TL-shaped DMS structure on microstrip line can reduce the EM flux through the damaged line by changing the current path, therefore, the TL-shaped DMS can reduce crosstalk by restraining EM coupling.

SIMULATION AND TEST OF S-PARAMETERS

In order to verify and quantify the effect of TL-shaped DMS structure on the transmission ability of microstrip line and the effect of crosstalk suppression, S-parameters simulation was carried out by using HFSS software, and make a real object to test with the vector network analyzer (VNA). Because the distance between the microstrip lines is too small to place the connectors at the same time, the three samples are made and tested respectively, two ports are placed on the connectors, the other two ports are connected to a high-precision 50 Ω resistor before grounding to ensure test accuracy. The fabricated samples are shown in Figures 8, 9 and 10.