It appears that antenna placement is critical to output. By constructing many of these circuits and connecting their outputs together, you could produce the energy to power a house. Remember each unit needs its own anntena. The best thing to do is to experiment with diferent lengths and sizes of anntenas. Every place on earth has diferent levels of RF power. Ofcource near large citys or near transmiters where RF is huge on air, the circuit works much better.
To get an idea of making the best anntena, Imagine that this unit as an all frequency radio reciever. A very critical point to consider is the earth ground of the circuit which has to be properly conductive.
An earth ground should consist of some type of metallic, conductive pipe or rod. Use the earth of your house or buy a new earth ground from the market hammer it as deep as you can for best results.