S
Member
Weighing options for a design, recording the trade-offs here.
1）Spacing below a quarter wavelength in the substrate stops dominant-mode leakage.
2）Tighter spacing also raises the cut-off frequency of the parallel-plate waveguide formed by the planes.
3）Via inductance adds to the ground return path; multiple vias in parallel reduce it.
4）For GCPW, the side wall spacing also sets the impedance, so it cannot be chosen independently.
Discussion welcome, especially counter-examples.
1）Spacing below a quarter wavelength in the substrate stops dominant-mode leakage.
2）Tighter spacing also raises the cut-off frequency of the parallel-plate waveguide formed by the planes.
3）Via inductance adds to the ground return path; multiple vias in parallel reduce it.
4）For GCPW, the side wall spacing also sets the impedance, so it cannot be chosen independently.
Discussion welcome, especially counter-examples.
