How can you tell if you need a better antenna?

I just setup PiAware on a Raspi B+ and started picking up aircraft positions immediately. From the looks of it, based on the web interface i’m seeing aircraft about 75 miles away on the basic antenna:

amazon.com/gp/product/B009U7 … fligh01-20

My question is how do i know if i need a better antenna, is it all about range? Is there something else such as accuracy / reliability that a better antenna would strengthen?

A better antenna will increase your range significantly. I built and tested several antennas and the best one by far is a ground plane antenna. I built one with four radials out of spare coax and get solid reception out to about 150nm but I do pick up planes over 200nm away.

Getting the antenna high, outside (or at least in the attic) and away from metal will also help significantly.

You can also increase your range by tweaking the dump1090 configuration (gain settings and whatnot).

Lastly, you can also mod your SDR dongle to get better reception.

I have the same set up as the OP. Positioned upstairs (but still inside) I get about 100-150 nm.

This is my sig for FR24 forum - has links showing what can be done with a dongle and an external antenna - my cover East - south is reduced by a gentle rise in the landscape to about a mile away, and there is a hill 2 miles away to the NNW.

Dump1090 map now → goo.gl/spOBpc (map shows UK if you see nothing)
RTL2832U / R820T

Note FR report Aircraft seen, FA report flights with ADSB seen … FA report is 2 - 3 times higher since I see most aircraft do more than one flight

A simple dipole outside clear of the roof top will give up to 200nm
the amplifier increased range by about 10% & aircraft count by 20%