Originally Posted by Paddy
If you ask
I intend to mount the antenna on an aluminum plate within the overhead console, and ground that plate to the airframe.
It is important to connect the coax shield to the plate, but it is not necessary to otherwise ground the ‘ground plane’.
The 430, and I think other Garmin gps boxes, have a signal strength display on the top right display page. It would be interesting to compare those pages between two similar aircraft, one with an internal, one with an external, antenna.
As a side note, I recently did experience a GPS failure. On a vfr approach, the gtn650 first downgraded from LPv to LNAV, then, as we touched down, downgraded further to no gps. External antenna. It would have been informative to have had a similar but internal antenna plane nearby.