Those dongles aren’t really good compared to dongles with integrated LNA (Low noise amplifier).
Get yourself a ProStick Plus from Flightaware (around 30 Euros) or a Radarbox Flightstick (around 15 Euros)
The Radarbox Flightstick is available from the AirNav store and is being discussed here:
Try the new dongle you buy with and without the filter you already have. (The new filter they are selling is better suited to block mobile phone signals in Europe. Still even without an added filter the either dongle i mentioned should improve your reception)