Update 16.02.2020.
Receiver is back online, but unfortunately with a much lower antenna position and antenna gain
Receiver is a SDR RTL2832. Antenna is for VHF and UHF reception only. Enjoy :)
You can listen to ATC frequencies:
Zagreb Approach/Departure: 120,7
Zagreb Radar: 135,8
Zagreb Radar: 132,125
Zagreb Radar: 130,215