Article / RF
3 Oct 2025
GNSS antenna layout on a cramped PCB
Keep-out, ground stitching and why the GNSS port wants its own world — lessons from a tracker that had to fit in a matchbox.
Two radios, one small board
Cellular MAIN and GNSS on the same PCB means two different ideas of “ground”. The GNSS path is receive-only and unforgiving; the modem path is transmit-first and loud.
We route them to separate connectors even when the module offers a combined antenna option. Field service and matching are simpler when the paths are not sharing a compromise.
Keep-out that actually helps
The keep-out is not superstition — it is where the return current for the GNSS LNA is allowed to flow without crossing the switching regulator.
Stitch vias on a 2–3 mm grid under the GNSS feed, but stop the flood under the matching network until the match is done. Moving copper after tuning is how you ship a beautiful layout that deafens the receiver.
Verification
Cold sky tests beat anechoic chambers for our scale. Log C/N0 on the bench with the board in the enclosure you will ship, then repeat with a hand wrapped around the antenna — that is the failure mode users invent for you.