50 Hz is too low a frequency to be a problem i think.
Also how would you get higher than 10 m? 
If anything they’ll just block some part of the sky a little bit.
But they should have enough air in between to allow signals through.
If you have other buildings or trees around you, placing the antenna higher than them will definitely help.
Be sure to check this thread out: What is the Maximum Range I can Get?
Seeing the horizon from where the antenna is, that’s what you want.