Hello all!  :)


I stumped on a problem with microstrip transmission lines. Yes, I did check the usual theory books, handbooks and cookbooks with no answer at all so far. Hope someone can give a tip here.


My problem:

I'm working on a somewhat complex PCB at 5.8 GHz and I am limited to 2 layers (one of them, of course, will be the ground plane). For microwave traces I used microstrip.

When routing power supply traces and control/low-frequency traces I realized I wouldn't be able to route them without crossing microwave traces (I must stress I am limited to two layers).

How to overcome this problem?

- Solution 1 - interrupt the low-frequency traces and solder a piece of wire over the microstrip, suficciently apart from it to avoid coupling. While this solution is enough for a single prototype, it is a bad idea for mass production. What do you think?

- Solution 2 - put two vias in the low-frequency trace so I can route it under the microstrip line for a few millimeters. I would prefer this solution since it is neat for production, but I would be creating a small slot in the ground plane just under the microstrip line, and I have no idea how this would afect line (and circuit) performance. What do you think?

- Solution 3 - I will gladly read other ideas from you.