That’s the worst antenna i know of. (I have no idea why they sell it as 1090 MHz)
A simple wire cut to 6.5 cm performs much better.
Try building a spider directly on the dongle:
QUICK SPIDER - No Soldering, No Connector
It shouldn’t be too hard 
What does that other antenna on the roof do?
Could easily interfere with reception.
(Even a receiving antenna with amplifier can be problematic as the some amplifiers produce interference)