RF density in concert hall
Discussion
Question for a Radio Frequency boffin.
Imagine you have a concert hall full of say 500 people and 90% of them have an active mobile device be it pad/phone/watch. The cell signal is not that good inside the hall so most of the devices have turned themselves up in a attempt at being heard.
What will the microwave RF density be in the middle of the hall ?
Imagine you have a concert hall full of say 500 people and 90% of them have an active mobile device be it pad/phone/watch. The cell signal is not that good inside the hall so most of the devices have turned themselves up in a attempt at being heard.
What will the microwave RF density be in the middle of the hall ?
Not enough information given to be entirely accurate; from the information available in the question;- given a maximum of 2W output on the 900MHz band and half that on 1800MHz , taking into account the inverse square law and the fact that a human body, being mostly water, is a very good shield at those frequencies, my guess would be...
bugger all.
Why do you ask?
bugger all.
Why do you ask?
Just an idle thought really.
looking down over an auditorium it always astonishes me what proportion of the public are actively fondling their hand held apparatus. Presumably booking their faces or twitting their tweets or something else I fail to see the point of.
Any how, I started pondering on how much heat they were collectively generating. Say 500 active devices and the cell signal was poor so each device was shouting as loud as it could. I am not certain if the 2W power standard is 2W input or 2W output. Say it is input and they are 50% efficient so 500W gets radiated collectively . Say half the radiation is adsorbed by the humans turned into heat and re-radiated. You have 500W generated directly by the devices and 250W by the people. So compared to the normal thermal output of 500 people 750W is probably next to nothing.
Then I thought about RF. With the example above and assuming each person is allocated roughly 0.6 Square meters you have 250W of RF not soaked up by the humans. In simplistic terms 250 /(500*0.6) or 1.2W Square M. So if you filled your entire 0.6m with an antenna you could harvest around 750mw to charge a battery or something. Sadly however with your seat filed of antenna you wouldn’t see the concert.
Suppose if I took up booking my face I wouldn’t need to worry about such things.
looking down over an auditorium it always astonishes me what proportion of the public are actively fondling their hand held apparatus. Presumably booking their faces or twitting their tweets or something else I fail to see the point of.
Any how, I started pondering on how much heat they were collectively generating. Say 500 active devices and the cell signal was poor so each device was shouting as loud as it could. I am not certain if the 2W power standard is 2W input or 2W output. Say it is input and they are 50% efficient so 500W gets radiated collectively . Say half the radiation is adsorbed by the humans turned into heat and re-radiated. You have 500W generated directly by the devices and 250W by the people. So compared to the normal thermal output of 500 people 750W is probably next to nothing.
Then I thought about RF. With the example above and assuming each person is allocated roughly 0.6 Square meters you have 250W of RF not soaked up by the humans. In simplistic terms 250 /(500*0.6) or 1.2W Square M. So if you filled your entire 0.6m with an antenna you could harvest around 750mw to charge a battery or something. Sadly however with your seat filed of antenna you wouldn’t see the concert.
Suppose if I took up booking my face I wouldn’t need to worry about such things.
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