I think the FlightAware antenna is doing the job pretty good.
Keep up the good work.
That’s looking great. I’m still trying to improve my reception and I think I’ve done about all I can. Can you tell us a bit more about your setup? E.g. R820T or T2? Amplifier? Dump1090-mutability? How high up is your antenna…
I am using the FlightAware antenna outside. The antenna from the ground up is about 16 feet. I am using RG-6 coax cable (Quad Shielded). The RG-6 cable is around 12 feet long, from antenna to the USB dongle. I am running a ASUS Netbook computer with Xubuntu installed on it. Running Piaware 2.1-2 and Dump1090-Mutability V1.15. Using USB NooElec NESDR Mini 2.
There looks to be something wrong with your setup, your range is so poor (sorry 
)
Maybe you have a bad connection somewhere between the antenna an dongle, bad antenna feed cable, antenna under a mineral rich roof covering, bad dongle, using the antenna that came with the dongle? (and in the attic)
what’s suprising is you have two Pi’s and they both have a low range - tell us how you’re rigged 