Reducing SAR - is it true?

john_s

I came across the so called ' pong' http://www.pongresearch.com/protecting-signal.html
I'm kind of curious and wonder how much of what they claim is actually true.

mike_m

If the antennas being used today in modern electronics were true omnidirectional antennas, which they aren't, then maybe this would be useable.

All modern cell phones, PDAs, laptops and other electronic devices that transmit RF, and even the cell phones GPS receiver, use 2 basic antenna designs called #1. Planar F or #2. Planar Inverted F antenna.

The main reason that these antennas are being used is because these antenna designs inherently direct the RF away from the user thereby reducing the radiation that would normally be directed towards the uses head if an omnidirectional antenna were used.

Basically the antennas that are being used these days in most if not all designs were chosen to meet or more so exceed the FCC SAR requirements so such a device is not really needed.

john_s

Interesting observation - I remember reading about some issues with iphone antennae performance when not holding the phone 'properly'. Obviously they're not omnidirectional. My knowledge of antennas is very basic, but as far as I know any receiving or 're-directing' antennae acts also as a transmitter. To re-direct the RF should require to absorb that energy first. From their sources I couldn't find any info on energy losses during that process.

According to TNYT "...Pong Research, based in Los Angeles and Middleburg, Va., manufactures cellphone cases with a patented pattern consisting of a metallic coupling loop and horizontal metallic stripes alternated with insulating materials....".

Some interesting reviews can be found here:

http://www.cnet.com/8301-17918_1-20105781-85/a-cell-phone-case-for-reducing-cell-phone-radiation/
http://www.wired.com/gadgetlab/2011/12/pong-ipad-case-investigation/all/1
http://www.engadget.com/2010/11/19/casemates-iphone-4-bounce-case-protects-your-noodle-from-inevit/
http://gadgetwise.blogs.nytimes.com/2010/06/01/anti-radiation-products-with-some-science-in-them/#more-29661

http://forums.hardwarezone.com.sg/mass-order-corner-251/%5Bmo%5D-pong-patented-phone-case-protects-you-3567176.html

mike_m

The I-phone problem was actually worse and a bit different.

The antenna was a slightly different design, as I remember, and it was placed in a position on the case where even though it met the SAR requirements towards the rear (towards users head) it was placed in such a bad location that the antenna was detuned by the users hand and the power dropped more than the design specs.


Their fix was to use an aftermarket case, which wasn't metallic either, so the fixer case only produced a separation distance from the user to the I-phone problem area.

In essence they made the case thicker with the separator piece but this piece still needed to be non metallic, as I remember, otherwise it would also detune the antenna.