The Brain Waves have the frequency range of 3 or 4 cycles/s to 15 or 20 Cycles per second, which is same as the Ionosphere - which has many different layers of resonating EMF Field and Ions, constantly bombarded by Cosmic Particles and Radiation.
Tesla when found the dual usage of his technology, he split his designs and gave to Russia, UK, USA and Canada. Russians made some advancements in 70's and it is said that the New York Black Out of 70's where the Edison Power Plant was completely burnt out was caused by the EMF Beams shot by Russia. The same beams were monitored by the HAM Radio Operators for a signal coming from Russia and messing with the Northern Aurora Lights. This was also confirmed by NASA that someone was messing and manipulating the Aurora Lights remotely!