before buying additional filters - make a scan with rtl_power to see what’s in the air at your site: Filter not producing desired result - #11 by obj in addition you can play a little with gain setting in dump or piaware to see what gain matches best when flightaware antenna is connected. there is a script here in the forum that sets different gain values - but to be honest i’m more a fan of doing it manually that gave at least me faster and more precise results.
in my one to one tests with about 10 different antennas the flightaware (you have) was runner-up with decent performance!
cheers
tom
p.s. this is how my plots looked like
