Nice job on the PCBs, they look great.
"The best" is of course subjective. What are your actual criteria? The return losses look decent over the measured frequency range, but only you know what you need...
Yes, the length of the line causes extra phase to be incurred.
How do we establish confidence? Compare simulated data to measured data. The simulation is ideally a duplicate of everything you have in reality, up to the SMA ports. Extract the same scattering parameters from the simulation and you should be able to assess your confidence.
Have you simulated the PCB in the enclosure? At the frequency range you're measuring, the conductive enclosure could cause some gnarly effects. Especially with a lid.
Hi Tobias,
in your measurement you need to make sure that there is no gap in ground at the location that I marked with the arrows. Ideally you would solder the backside ground to the connector body or box, but it seems that your box can't be soldered. Some copper foil should be good enough then.
If ground current can only flow through the screws that are left and right from the line, that is a massive detour for ground path current, resulting in series L at the connector-PCB interface.
View attachment 190389
Hi Tobias,
in your measurement you need to make sure that there is no gap in ground at the location that I marked with the arrows. Ideally you would solder the backside ground to the connector body or box, but it seems that your box can't be soldered. Some copper foil should be good enough then.
If ground current can only flow through the screws that are left and right from the line, that is a massive detour for ground path current, resulting in series L at the connector-PCB interface.
View attachment 190389
One more Q: if you look at the result from my soldering
this is certainly not perfect.
I mean, too much solder I guess?
The central trace can interact with the enclosure, even with a solid connection between your other PCB traces and the enclosure. In the worst case, this could cause your system to operate more like an antenna or filter. It's unlikely, but best to check in simulation if possible. Simulation with the enclosure is part of any good RF deign process.No, I haven't, only the PCB trace without enclosure and SMA. But the manufacturer of the enclosure did, I am using:
Yes, I would say there is too much solder; the solder should be flat (or as otherwise specified by the connector manufacturer, there are often instructions in the datasheet). Use braided solder wick to remove some of it for best results. At ~3 GHz, you could see a difference in the response.One more Q: if you look at the result from my soldering
I reviewed the thread and didn't see a target S11 or VSWR specification for the design. Even perfectly mounted RF connectors involve a certain amount of reflections. So hard to say if your design is bad, good or even over-engineered. May be your spec is "as good as possible"?
We use cookies and similar technologies for the following purposes:
Do you accept cookies and these technologies?
We use cookies and similar technologies for the following purposes:
Do you accept cookies and these technologies?