Librem 5 SAR (or DAS)


#41

Emanations then, picky, picky, picky.


#42

I agree that radiation exposure should be minimal at the first place and @Caliga already covered basic advantages of Librem 5 when referring to “possibly sufficient space on the PCB to have good antennas”. One of good antennas solutions is usage of Metamaterial-Embedded Low SAR PIFA for Cellular Phone, covered with this statement: “The achieved SAR reduction by metamaterial is 42.12% and by Materials 47.18%,which provide information to design metameterial based antenna for minimize biological effect on human body due to EM radiation.” On radiation exposure of popular mobile phones specifically, professor Gert Frølund Pedersen presents in this study some measurements of total radiated power (TRP) … that includes free space (FS), Fig. 1(d) because “for most of the bands the introduction of a human hand increases the spread among the phones and it is around 5 dB”, etc. Qualcomm® 5G modem-to-antenna solutions are complex as well but head SAR and body SAR are just barely under 1.6 W/kg. We all expect good SAR values from Librem 5 and I am sure that those will be known with batch Evergreen (if not earlier).


#43

In France, a law due to come into force in July 2020 limits SARs to :

  • 2 W/kg for head
  • 2 W/kg for trunk
  • 4 W/kg for member

Test condition is 0mm distance between device and skin.

We are now at the Chesnut batch. Do you have any clarification on this very important point from a health point of view? Thank you.


#44

ok but that is only the law it has nothing to do with actual real-world spikes in SAR values.

you enter a tunnel or some low signal area and your SAR will go up temporarily because it needs to compensate … some real world examples are in order (not the lab ones)


#45

It’s impossible to measure SAR before the final design is available (batch Evergreen with moulded case).
But, considering the thickness of the Librem 5, it shouldn’t be a problem.


#46

Of course you are right, there is labs and real life conditions, but at “normal condition” (let’s say outside with good signal), I would be happy to know how much SAR I absorb (head, body). My fear is, as the L5 is not like other smartphones, the network module is in M.2 slot, and the design is different, so I hope SAR won’t be too high.

@Torrone I understand that it is better to get results with the final design, that’s a good remark.


#47

Here is some reference data. Best phone so far seems to be Samsung Note II, old but cancer-safe (0.17 head SAR), while iPhone 5 is 0.9. Newer iPhones are much higher, close to 1.6 max limit.

Studies link SAR radiation to brain cancer unfortunately. Phone companies hide this info as much as possible but it is serious, so I hope Librem 5 takes a lead here, and gives us another major reason to buy it, in addition to privacy and security. Thank you



#48

thankfully I don’t do much calling