What are the electrical characteristics of the human body? Human data sheet - Page 1
Forum section: electronics / general

author: Beamin
author_rank: Super Contributor
timestamp: May 28, 2018, 05:00:12 pm
content: If we could measure a person what kind of:Resistance per meter, internal resistanceCapacitance in general and when standing around 60/50 HzVoltage on skinAmperageResonance; this is an interesting one I read some where that the human body is tuned to 100 MHz. I know standing(climbing to the top rather) around big TV towers is dangerous and will make your ears/eyes/nose bleed. But what happens at 100Mhz assuming that's where it resonates at? Is that because we are 2 meters long like 3/5 wave length? Water is tuned to 2.45Ghz. Is this 100 Mhz figure related to why just moving around a room has so much effect on an FM radio and why not so much on other bands? I once made a really simple one transistor transmitter with no modulation or crystal and to get to oscillate at around 80Mhz you had to walk near it placing metal or magnets around it didn't do anting unless it was directly inside the coil. It drifted like crazy as you moved but metal objects near around it had no effect. Some times you had to jump start it by touching the coil or sticking a nail in the coil.

author: IanB
author_rank: Super Contributor
timestamp: May 28, 2018, 05:09:37 pm
content: Quote from: Beamin on May 28, 2018, 05:00:12 pmInstead of asking, why don't you measure yourself to find out? I thought this is an experiment that everyone does when they first get their hands on a multimeter.Hold the probes in your fingers. What resistance do you see?Dig the sharp points of the probes into your skin. Now what resistance?Try again with damp skin.Try with probes far apart (one in each hand) and close together (both in the same hand). How much variation in resistance do you see?

author: Richard Crowley
author_rank: Super Contributor
timestamp: May 28, 2018, 05:32:27 pm
content: There are standard circuits for simulating the "Human Body Model" for purposes of testing/measuring ESD performance.For example:I see no support for 2.4GHz as any sort of "resonance frequency for water". Conversely, most of the references I saw debunked the notion.I also don't see any support for the effects of 100MHz on the human body. 100 MHz was used for TV broadcasting in Eastern Europe, Australia, and as the upper limit of the Japanese TV bands, but I believe they are the old analog standards, now obsolete. And 100MHz is in the middle of the FM radio broadcast band in most of the world. Workers regularly climb even high-power broadcast transmitting towers without any of those reported symptoms.Your body affects FM radio reception more than other types of radio reception because all those "other" kinds of radio reception are at much lower frequencies and much less affected than higher frequencies. Note that your body has even MORE impact on higher frequency reception (such as UHF television, etc.)

author: capt bullshot
author_rank: Super Contributor
timestamp: May 28, 2018, 05:42:15 pm
content: There are many FM radio station around 100MHz here - but evolution hasn't developed a way to take advance of the resonance yet. Otherwise one could listen to the radio without any further technical means

author: IanB
author_rank: Super Contributor
timestamp: May 28, 2018, 06:19:06 pm
content: Quote from: capt bullshot on May 28, 2018, 05:42:15 pmActually there has been the odd story in the news of a person who picked up AM radio through their teeth (somehow a filling or some bridgework acted like an antenna and detector such that they could hear the radio inside their head).

author: NiHaoMike
author_rank: Super Contributor
timestamp: May 28, 2018, 07:28:27 pm
content: A particularly interesting electromagnetic property of some human bodies is the way they backscatter waves in the 430THz to 750THz range, or more precisely the way the waves get arranged in the process.They also emit waves with a peak around 31.6THz or so, the exact peak frequency theorized to have some correlation to how easy it is for someone to maintain a healthy weight.

author: babysitter
author_rank: Frequent Contributor
timestamp: May 29, 2018, 03:58:09 pm
content: Depends a lot. Basically we are big bags of salt water, surface effects are strong (big electrode with liquid film to body vs. small ball attached to dry skin). Attaching low currents get different results to high currents.Quote from: Beamin on May 28, 2018, 05:00:12 pmJust didn't happen to me climbing on VHF antennas, but i prevented getting to the immediate UHF antenna proximity.At RF, "The body" by itself does nothing, it depends on power levels and type of coupling. You need to get RF to it. Touching a wire carrying RF can bite, I guess i am not the only one who experienced it. You can cook a person by applying too much, of coursePlease ask for advice before you cook yourself during your experiments.

author: Beamin
author_rank: Super Contributor
timestamp: May 31, 2018, 04:20:36 am
content: I was watching a documentary where workers had to climb an antenna while it was on and they said you start bleeding if you are up too long or if you have chocolate it will melt and metal on you heats up. Most towers have big yellow signs that say "RF radiation do not enter while powered up". I know you can't send people to the top of TV towers while it's on. I believe microwave ovens work because 2.45 GHz is a multiple of water or its bonds. How is an RF burn different then an electrical burn? Still seems weird how lower frequencies would effect people. I saw a YouTube video where a guy is fixing a tube TV sticks his hand in and gets an RF burn but I don't know how he knows that other then years of working with tube radios.

author: CNe7532294
author_rank: Regular Contributor
timestamp: May 31, 2018, 09:22:08 am
content: Quote from: IanB on May 28, 2018, 05:09:37 pmI get no resistance. It just slips in and red stuff comes out. Plus it hurts.Joking aside though, try using a freshly slaughtered pig section from the butcher's and have fun turning up the volts at a safe distance. Not exactly human or living but great analog to learn from.Didn't mythbusters do something like this already? I lost track.Btw I'll give a hint. It gets worse as you turn up the volts (try kV with no current limit if you can safely). Figure why that is? Now imagine if this pig section was living, had a functioning circulatory system and was still a part of that pig.I don't think I need to explain further....Curiously though, people have been documented to survive a direct lightning bolt with only a neat Lichenberg tatoo. This generates Volts in an instant that we could only dream to match. A far cry from what is observed above. Why do you think that is? Link :https://www.sciencedirect.com/science/article/pii/S1364682615001261

author: CNe7532294
author_rank: Regular Contributor
timestamp: May 31, 2018, 09:49:50 am
content: Quote from: IanB on May 28, 2018, 06:19:06 pmLucile Ball aka the person who stars in I Love Lucy. You'd have to either be of age or watched Nick at Night to have known what that show is. I believe Mythbusters couldn't make it work. Have to rewatch if true.Quote from: Beamin on May 31, 2018, 04:20:36 amYou're on track. Think nervous system. Tell me. How much time does it take for you to register a stop light then react to it? How about something quicker like unexpected fireworks going off? Or how about a simple reflex that doesn't require going to the brain for processing. Like the classic knee jerk. Are any of these reaction times anywhere near the time period required to produce say a GHz signal? or even MHz signal? How about kHz or just 10s of hertz like the 50 or 60Hz from your wall socket?In any case RF burns are real and are delayed in showing signs. Its actually quite scary stuff but normally people survive this and heal 100%. Could be worse. Radioactive poisoning from acute nuclear material exposure works insidiously like this too but is 1000x more horrifying. Knowing that you'll die is just a small part of the horror.Quote from: NiHaoMike on May 28, 2018, 07:28:27 pmGreat use for medical.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: May 31, 2018, 02:43:24 pm
content: Quote from: Richard Crowley on May 28, 2018, 05:32:27 pmWhere did you get this...... wait, Maxim?*Hits the quote button*Ah, yep... Maxim.One of the weirdest appnotes, they call it "IEC-1000..." throughout (61000-4-2 is the correct number), except for one point where they call it IEEE-1000Tim

author: NiHaoMike
author_rank: Super Contributor
timestamp: May 31, 2018, 03:52:13 pm
content: Quote from: CNe7532294 on May 31, 2018, 09:49:50 amIt's definitely an area worth researching. The instruments to detect such waves are way cheaper nowadays than they were in the past. Also have to find ways to compensate for environmental conditions and amount of exposed surface area since those will easily mask the relatively small difference caused by the internal conditions we're trying to measure.https://en.wikipedia.org/wiki/Black-body_radiation#Human-body_emissionPretty interesting that with no airflow, about 2/3 of the heat is dissipated as electromagnetic waves!And on a only slightly related note, it looks like it's time to fire up some shaders to process data from digitizing 430-750THz in a lab on the other side of the world. With the digitizing being done in a grid of over 2 million points for a total of over 186 million data points collected every second, I wonder if that counts as massively MIMO SDR...