• shortwavesurfer
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    3 months ago

    The higher the frequency, the worse that is. So standing very close to an HF antenna that only broadcasts up to like say 30 megahertz is different than standing next to a 700 megahertz cell phone antenna, which is different from standing next to a 2.5 gigahertz cell phone antenna. The reasoning for that is due to power levels and wavelength of the radio signal itself.

    • deranger@sh.itjust.works
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      3 months ago

      Humans are most sensitive to EM radiation between 30-300 MHz. It tapers off after that, it’s not linear where higher = worse for you across the entire spectrum.

      https://www.fcc.gov/engineering-technology/electromagnetic-compatibility-division/radio-frequency-safety/faq/rf-safety

      In the case of exposure of the whole body, a standing ungrounded human adult absorbs RF energy at a maximum rate when the frequency of the RF radiation is in the range of about 70 MHz.  This means that the “whole-body” SAR is at a maximum under these conditions.  Because of this “resonance” phenomenon and consideration of children and grounded adults, RF safety standards are generally most restrictive in the frequency range of about 30 to 300 MHz.

      • shortwavesurfer
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        3 months ago

        What about those military things that they use to disperse crowds? Where it makes you feel like your skin is cooking, but it’s actually not. I feel like that uses high power and high frequency radio waves to accomplish that.

        • Chronographs@lemmy.zip
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          3 months ago

          This? it says that uses 95ghz which seems to be another frequency that is absorbed well. It’s not just because it’s cb high frequency, there’s specific frequencies that resonate with different things. Also it is definitely cooking your skin and you would be burned if you were hit long enough

          • 0x0@programming.dev
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            3 months ago

            Won’t that increase probability of skin cancer?

            Edit: yes:

            there is an extremely low probability that scars derived from such injury might later become cancerous

        • deranger@sh.itjust.works
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          3 months ago

          Those are 95 GHz but very high power and focused as well.

          It’s not that high frequency can’t hurt you, what I’m trying to say is for a given power level, 30-300 MHz is the most risky to humans. That’s why the FCC regulates this band the most stringently.

          • shortwavesurfer
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            3 months ago

            Fair enough, there’s some really golden information in this thread.