radio waves, as sent out and received by people's minds
 electromagnetic interference;  radio interference
 frequency hijacking;  broadcast signal intrusion
 somebody who has wild fantasies;  someone who hears voices;  someone who is crazy
 low-power transmission;  weak signals
 radio astronomy observatory
 television air time cost (for commercials);  broadcast fee
 standard time and frequency signal
 radio-frequency engineering
 (radio) channel occupancy