@Spocki: Thanks, that's what I'm currently using but in real live I can not reach 500m or more with this solution.
Short project description: In my application I'm measuring voltages. One unit is placed on a daily fixed position and is used as reference. With the 2nd unit in the hand I walk around and do the measurements (like a master unit that triggers also the measurement for the reference unit). A directional solution is a good idea but will not work for me.
Data Rate: The data rate is low, lets say around one measurement every 10s.
Retries: are ok.
Required range: 500m - 1000m in real live
So I'm not sure if the NRF24L01 module is the best solution for this.
Thanks & regards, Andreas