That somewhat suggests terrain around your location is blocking reception.
Are there hills around you?
Could also be that you’re getting strong interference, in that case you need a filter, i’d recommend getting this:
New Product: RTL-SDR Blog 1090 MHz ADS-B LNA
With the LNA added your gear might be called a proper car, ferrari is still something else and would mean a name brand antenna and LMR 400, maybe an airspy SDR 
Running a scan for intereference as described here might be enlightening:
Do I Need A Filter?