The FA antenna test requires a signal generator at 1090MHz (the ADS-B frequency) and comparing the return signal from the antenna. The test equipment cost much more than the antenna.
40 miles range is like any random wire antenna range. You can literally place any bare wire on the end of the coax and should see something this far every so often. It doesn’t require much to pick up a signal that far.
Good tuned antennas will pick up both range AND message count. If you are only getting range but no message rates comparable to the range there is something wrong with your antenna or cables or something.
If you look on your ADSB stats page it will have a section near the bottom called “nearby sites”. It will list nearby sites and their plane count (this correlates very well with range) and message count.
It is showing your site at 217 planes and 7600 message count in the last day.
This site is a few miles away and is a good comparison.
637 planes and 136,973 messages
Yea, something is not working. Hard to tell what is it at this point.