Two questions on designing a tuning varactor based BPF

Hey, I have two questions here need some advices.

For the tuning varactors, how can I bond them with the short-circuited stubs fabricated on RT/Duroid substrate? The stubs widths are 750μm. Can I use wire/ribbon bond? Or I just solder them togehter? The whole device will operate at X-band. I've read many papers but can't find any answers till now.

My second question is about the via/grounding tehcnique.
Once I designed an X-band BPF using 4 short-circuited stubs that are λg/4 long with with three connecting lines λg/4 long also. However, due to the poor via method, the measured S21 is much worse if I use the open stub technique. I grounded those stubs using silver paster which seems not a good way at all.
So, could you please give me some advice on how to ground those short-circuited stubs?

Thanks,

Joe

Put more vias in parallel (up to 4).

Better if you can model it in 3D and analyze.

you can then able to decide what is the location of vias, via -diameter and how many are required etc.

Thanks for the advice. I think I need read more papers then.