RF: what are some sources that are transmitting few hundred of watts signal power?
Wikipedia has a small list to get you started:


  80 dBm - 100 kW
    -- Typical transmission power of FM radio station with 50-kilometre (31 mi) range
  62 dBm - 1.588 kW  -- The maximum legal power output of a U.S. ham radio station.[3]
  60 dBm - 1 kW -- Typical combined radiated RF power of microwave oven elements
  50 dBm - 100 W -- Typical thermal radiation emitted by a human body. Typical maximum output RF power from a ham radio HF transceiver