I also bought those, and found that they had far worse reception than my home built antennas. I have made and tested quite a few, but two designs have stood out far above the rest.
- easy to build
- good range (I get over 150nm consistently, and 200+ occasionally with it in a second story window, and many obstructions around. )
- kind of fragile/hard to mount
- ugly
- J-pole: ADSB J-pole Antenna and the calculator here: Slim Jim / J Pole Antenna Calculator
- not quite as easy to build (I ordered some semirigid coax off amazon)
- spectacular range (I now consistently get 200nm+, and my messages per second were double what I got from the cantenna
- super durable
- inconspicuous
The cantenna is dead easy to build, and gets about 4x the messages per second that those junk rubber duck ones do. I can’t recommend the J-pole enough though. I was shocked at how well it performed. It gets another 2x messages per second than even the cantenna at my location.