I've been working on a design that requires me to pass an RF signal through a conductive panel. I'm using SMA jacks for that purpose as they're readily available and also available in an isolated configuration like these. The reason I'm using an isolated jack is to avoid a ground loop through the chassis and up the electronics assembly. Here's an image of what I'm doing:
This image shows the return current path or ground (blue line), as if I were using a standard SMA panel jack where the shield would be electrically connected to the case like this. So assuming I instead use an isolated jack, I'd remove the return path through the case. The problem now is that I've gotta get the assembly to be IP67 rated. I cannot seem to find any isolated RF jacks that also offer any kind of ingress protection.
The GPS receiver provides a DC signal to the antenna external to the assembly for powering a LNA, so breaking the ground at the connector is out as I cannot have the return LNA current, or RF return for that matter, returning through the case and up the electronics as that would surely wreak chaos on my signals.
Does anyone have any suggestions? I'm not an EMI/EMC expert but have been reading a bunch on the topic, though I still have a ways to go in developing an intuitive approach for nuanced situations like this one. Thanks.