I’d suggest to roll your own antenna: Three Easy DIY Antennas for Beginners
Scroll to the Easy Antenna #1 Spider. I made one of these that rivals the FlightAware antenna. I ran mine on RG6 for some time but then switched to LMR-400. Def better but I had the cable in hand. I do use the KMR-400 cable mentioned above in a scanner installation and it’s excellent and affordable(ish).