(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.