Martin,
I agree with Paul. If you can fit external antennas, especially on a metal aircraft, they significantly reduce the likelihood of signal obscuration by aircraft metalwork and big bags of fluid (us). Over my 5 years with PilotAware I have done extensive testing of antennas and in my experience, external antennas mounted below the pod on my flexwing (in my case with an internal aluminium foil ground plane) are giving the most reliable signal of any setup I have tested so far. Just remember to keep the (shorter) 1090MHz one in particular as far away from your transponder transmit one as practicable to minimise the possibility of interaction between your transponder and the PAW 1090 Receiver. There are lots of RV users out there who can advise on best locations.
Best Regards
Peter
p.s. If you feel you have bought the wrong thing, drop an e-mail to Ash at PilotAware Support. I’m sure he will be able to help.