Wireless Communications/EMF and Lead


QUESTION: Would lead as a material block or inhibit the transmission of electro-magnetic frequencies?

ANSWER: Any electrical conductor will block radio frequency (RF) electromagnetic energy.  A solid sheet of conductor is not required; at frequencies into the microwave region a mesh can be effective, too.  Lead is a fair electrical conductor, but aluminum or copper are far better RF shields.
Radio frequency 'screen rooms' are often built with copper mesh.  A two-layer screen room with careful attention to seams and with special conductive door seals can achieve 120 dB of RF isolation.

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QUESTION: The reason I ask, is that I will be laid up in the hospital for another month, and I'm attempting to get as much work done with my laptop resting on my, well, lap. Very concerned about potential negative effects of this on reproductive organs. This particular laptop runs extremely cool and the settings used enhance this (temperature being the first and only documented potential threat to semen) but the jury is still out on EMF. I have a led film bag, and could probably acquire a copper/alluminium barrier if that's preferable. EVEN IF IT THERE IS ONLY A REMOTE potential benefit of protection as a while away 5-8 hours a day in bed, laptop resting 1 cm aware from the region, I would prefer to do this and error on the side of caution. Hence the questions.

I understand your concern is the possible health effects of RF energy.  I am not a medical expert, but I have followed the health debate on RF exposure and I will summarize that from the engineering point of view.
RF energy is non-ionizing, that is, its impact on living tissue is mainly in the form of heating.  Much higher energy radiation can be ionizing, which means its effects can be seen as changes to the organic molecules in tissue.  X-ray and cosmic rays are examples of ionizing radiation.  Dense materials, such as lead, tend to block or shield such ionizing radiation better than lighter conductors such as aluminum.  
Cellular and WiFi signals are far down into the non-ionizing portion of the electromagnetic spectrum.   The best way to reduce exposure to non-ionizing energy is to increase the spacing between yourself and the source of the signal.  That's because the absorbed power is proportional to the inverse square of the distance:   If you double the distance between (say) your cell phone and your body, the power level at your body is reduced by 2 squared, or 4 times.  
I don't believe a laptop computer emits any measurable level of ionizing radiation.   Older CRT terminals did produce a small amount of low-energy x-rays due to their operation principle, but that is not true for LCD displays.
Placing a pillow between you and your laptop will increase the distance by perhaps a factor of 10, as a rough estimate, which would reduce the incident power from the WiFi transmitter in the laptop by a factor of 10 squared, or 100 times.  The pillow will also insulate you from the thermal heat of the laptop, which I've found to be uncomfortable after a time.  

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Jerry Hinshaw


RF and microwave engineering, hardware and systems applications. Avionics, satellite, and terrestrial communications. Space communications and navigation, geo-location services via satellite and ground-based wireless systems. Systems integration of RF and wireless services. Electric Utility RF Smart Meter (SmartMeter) and Smart Grid wireless devices and networks. Utility Distribution Automation.


30 years experience in microwave and RF systems engineering, radio hardware design and development.

about 20 articles, 2 patents

BSEE MSEE Communications Systems

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