I recently was able to move my feeder from my home location to the top of a single story building, which obviously greatly improved performance.
However, my initial install location was quick and dirty. The antenna was zip-tied to the side of an air handling unit, with the lower 1-2 inches of the antenna obscured by the metal frame of the A/C, and little to no elevation above other roof obstacles.
I recently changed the mount to the top of a (relatively short) PVC mast hoping to gain a bit of reception by clearing line-of-sight over the other air handlers on the roof.
After this change, I saw a quite noticeable drop in message rate & aircraft tracked.
I only tested it with the new setup for 45-60 minutes before returning it to the previous install, and saw the message & aircraft stats return to expected levels.
Can anyone explain why this happened, or what I did wrong?
My mounting locations are limited, since the only accessible roof penetration is the one for this AC unit, so to mount it elsewhere would require longer cable, and still need to be attached to an AC unit or vent pipe on the roof.
- Antenna: ADSBexchange 5.5dBi 1090/978 26"
- Feed coax: 10’ of S-LMR240, pre-terminated
- LNA (after the 10’ coax run): GPIO Labs Dual Band Filtered LNA 978 MHz + 1090 MHz
- From the LNA, it goes to a splitter, then each pigtail goes to a RTL-SDR Blog V3 dongle, into a RasPi4.
Original install (which did better):
“New” install (which did worse):
The period marked was the new mast installed: