The iPhone 4 uses the metal edge of the phone as its antenna. This means that it’s pretty easy to make contact between the antenna and your hands. As you’ll know if you’ve ever grabbed the antenna of a TV or FM radio, the human body conducts, and can have a pretty big effect on reception.
Users are now reporting that it’s true for the iPhone too. You can lose most of your signal strength by holding the phone the wrong way.
What I haven’t seen anyone discuss yet is the effect on the phone’s Specific Absorption Rate (SAR) caused by the antenna making contact with your hand while the device is transmitting. I know that making contact with a high powered radio mast can cause RF burns, so antenna contact definitely can result in much more energy reaching your body via conduction than you get exposed to by radiation from being next to the antenna. So it seems to me that there will be increased EM exposure from having sweaty fingers in contact with the iPhone antenna most of the time it’s transmitting, and I doubt the standard measurement methods for estimating SAR allow for this factor.
So, does anyone know how SAR levels change if you’re physically in contact with the antenna? Has anyone seen any discussion of this? Apple’s engineers must have thought of this and allowed for it when setting transmission levels, right?
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