I want to the CPW transmission line S11 below -20dB, how to reach that? Is that my port set wrong in EM simulation?
Thanking for any answer.
The substrate for microstrip line (permittivity =4.6, the h=1mm, the width of 50Ω is 1.80mm )
The substrate for CPW line (permittivity =3.5, the h=0.5mm, the width of signal path is 1.5mm, the gap is 0.15mm)
：Both is 50Ω caculated with TL tools
In EM simulation: The max S11 for CPW only reach to -15dB (increase the mesh, use edge mesh, uncheck the Mesh reduction)
The max S11 for Microstrip line only reach to -20dB (increase the mesh, use edge mesh, uncheck the Mesh reduction)
However, In HFSS, Microstrip Line, S11 can easily reach to -30dB or -35dB (no need much tuning)