RF is cube root I believe - nope, inverse square law, sorry - from an isotropic radiator. So 1000mW from your wlan AP is very quickly 10mW, at 10 meters.
Lightning exists and that's on the scale of 64gigawatts of energy, I have a differential lightning detector that can "hear" lightning roughly the entire hemisphere. I had to make the antennas. Blitz system blue.
Clear channel broadcast stations (the FCC term, not the company 'ClearChannel') must output 10KW - 50KW no more and no less.
If you're within a dozen or two miles of one that is beam-formed, you can pick it up with basically any semiconductor, a wire, and a speaker. Like, a resistor will work.
edit: I can probably do a demonstration video with a VNA/antenna analyzer and an HT radio, if such a thing doesn't exist. But the "voltages" that radios can detect can go as low as, well, i'll quote one of my radios specs:
> Sensitivity: -140.0 dBm (0.02 µV / 50 ohms at 15MHz) MDS Typ. at 500Hz bandwidth in HF
> Sensitivity: -141.5 dBm MDS Typ. at 500 Hz bandwidth in FM Broadcast Band (64 – 118 MHz)
> Sensitivity: -141.0 dBm MDS Typ. at 500 Hz bandwidth in VHF Aviation Band (118 – 260 MHz)
i was only able to test that radio to -136dBm or so. I forget why, i think the service monitor i was using was really old and probably needed some new caps and a decent interior cleaning. But the radio specs claim it can detect 2 hundredths of a microvolt in specific circumstances (like detecting a very faint beacon signal)
Lightning exists and that's on the scale of 64gigawatts of energy, I have a differential lightning detector that can "hear" lightning roughly the entire hemisphere. I had to make the antennas. Blitz system blue.
Clear channel broadcast stations (the FCC term, not the company 'ClearChannel') must output 10KW - 50KW no more and no less.
If you're within a dozen or two miles of one that is beam-formed, you can pick it up with basically any semiconductor, a wire, and a speaker. Like, a resistor will work.
edit: I can probably do a demonstration video with a VNA/antenna analyzer and an HT radio, if such a thing doesn't exist. But the "voltages" that radios can detect can go as low as, well, i'll quote one of my radios specs:
> Sensitivity: -140.0 dBm (0.02 µV / 50 ohms at 15MHz) MDS Typ. at 500Hz bandwidth in HF
> Sensitivity: -141.5 dBm MDS Typ. at 500 Hz bandwidth in FM Broadcast Band (64 – 118 MHz)
> Sensitivity: -141.0 dBm MDS Typ. at 500 Hz bandwidth in VHF Aviation Band (118 – 260 MHz)
i was only able to test that radio to -136dBm or so. I forget why, i think the service monitor i was using was really old and probably needed some new caps and a decent interior cleaning. But the radio specs claim it can detect 2 hundredths of a microvolt in specific circumstances (like detecting a very faint beacon signal)