Librem 5 SAR (or DAS)


I love the idea of the Librem 5! However, I would like to know the amount of radiation it will emit before committing. Do you know the level of SAR (or DAS for us French)?
SAR definition:

In my opinion, it should be as low as possible as this subject is becoming a matter of public health (this is my primary criteria for a mobile phone). This could also be a key differenciator as most phones (especially iphones or chinese phones) have very high SAR.

Many thanks!



Of course we will try to reduce the SAR as much as possible. The final values can only be told once the hardware design is finalized and we can not yet do so before having successfully finished the campaign.



Since the campaign is finished, could you please give some updates regarding the SAR values?


I think the hardware choices are still not definitive, but Purism team will have a more complete answer.

EDIT: you might be interested in this post from Todd

Yes, exactly, we have to finalize the hardware first.

A lot of things are still in flux and we have to start negotiating these with hardware manufacturers and supply chain. Currently we have a lot of balls in the air to juggle. The SAR will depend on the modem choice and on the case design as well as antenna design and positioning. This again can only be done and completed once we have kind of a final mainboard design.

We are currently targeting end of April / beginning of May to have first designs, but this can still change if we get more i.MX8 delays. Currently we do not even have full datasheets for the CPU since NXP does not release them to the public yet, announced date is now February 2018. We are confident that we will be able to use the i.MX8 but it makes our schedule extremely tight.

We do the best we can but are limited to what we find on the market. We have contacted almost 100 potential manufacturers, just to give you an idea on what we are working on here. We will have to narrow this down in the next couple of weeks, fly to Asia, talk to a narrowed down number of them, choose one, start the design with them taking into account their supply chain etc.

As I said before, we will have an eye on the SAR and will do the best we can to reduce it to a minimum but we can not give any number before we have a first prototype and having it measured in a lab.



Hi @nicole.faerber ,

Thanks for the detailed answer. Quite a few backers reported they lack of information regarding the project.
I personally think a roadmap regarding the next big steps for the Librem 5 would be very welcome.

Your post already has very valuable content (though maybe a bit too “low level” for it to be updated regularly?). Why not expanding it a bit and turning it into a roadmap comparable to the freedom roadmap?



I perfectly understand that SAR value will be determined by component choosen. In my humble opinion, having the lowest SAR possible should be set as a priority as it can rank quite widely. If you wish figures, I would expect a SAR comparable to a Galaxy Note II (
Surely if this low rate could be achieved six years ago, this should not be an issue nowadays (if a little though and will is put to it).
Any way, keep on the good work and let us know!
Best regards,

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That’s probably because they have full metal cases, which are opaque to radio waves and thus they need to turn the case itself into the antenna. If you directly touch an antenna (make electrical contact with it), your body becomes part of the antenna circuit which a: dumps power into you (a very small amount of power, all it does is cause a local temperature increase which your circulatory system deals with automatically) and more importantly b: ruins the antenna’s radiating properties thus requiring some kind of expensive active compensation circuitry.

Something with a plastic case and an internal antenna (which is hopefully what we get) won’t have this problem.

sorry for my bad english i m french.
a) your project interests me a lot. but I am very sensitive to the waves
so i would also like the information on sar.
b) to know if we can pass in flightmode. at night and receive calls automatically in the morning.

thank you

This is for me the last uncertainty which really matters to have a buy decision.

All the software is open, so writing a program which switches the modem off and on at certain times automatically or manual request is no problem. The modem has not been chosen yet, so it still to early to estimate or even measure the SAR value.

If you really want to be woken up by a phone call when your phone is in flight mode, this is only possible if you redirect calls to a fixed line in this case. If you don’t risking disturbing other persons you might simply move the phone to the place most distant from you in the room and increase the ringing volume, this reduces the radiation you are exposed to a lot.

please include in your testing procedures the following:

1.SAR mesurements in perfect signal conditions with or without external bumpers .
2.SAR mesurements in very low signal conditions with or without external bumpers.

@ everyone

please keep in mind that SAR radiation is higher in very low signal conditions during calls and when you are moving fast it is greater still.
manufacturers recommend to keep devices at least 1 inch away from body at all times in case of extended periods of time usage.
wired headphones are recommended at all times when possible during calls and any kind of voice chats. wireless/bt influence is an added concern to public health.

I assess homes for radiation exposure after being trained as a radiation specialist and seeing my wife’s cancer healed up after taking out the WiFi and ELF’s in the bedroom wall but I became electro hyper sensitive (or microwave ill) after a CT scan three years and have one client who is far worse than me living in the bush in a tent because of microwave pollution and we have 6000 people in Victoria alone. It a growing phenomenon worldwide. (US Navi already bank in 1971 linked 120 illnesses to microwave radiation the now declassified papers online) SAR standards are obsolete standards and based on thermal heating (now we know that EMF opens up the Voltage Gated Calcium Channels causing oxidative stress and DNA damage via the Krebs Cycle - see work of Dr. Martin Pall) but at least there is something to look at. Using a mobile phone gives me painful symptoms depending on how high SAR level are and length of use (painful temples, burning hand, pressure on the chest, heart palpitations. electrical pain in ears and exhaustion) and even the Samsung Note is not perfect of course but better than the rest. I really hope this phone will keep radiation as low as possible. Thanks.

sorry for my bad english first.

@ everyone

there is a standard in the head. and the standard for the body. in France the law requires to say the two numbers

currently the best compromise is the

galaxy mega 6.3 sar 0.14 and 0.20
galaxy s4 sar 0.26 and 0.26

@planitsoon11 your galaxy note 8 is 0.17 head but 1.29 body…

An interesting video about RF Radiation from antennas. See where Samsung places their antennas to reduce radiation as much as possible.


Hi @Miguel. Thanks for those stats. I bought a second hand Note and used to have a Note 3 but that broke down. The Note 4 I use now though took me weeks to adjust to as the levels are higher and more painful :wink: Will have a look at the models you mentioned. Thanks :slight_smile:

planitsoon personally I use galaxy mega 6.3 but with Resurrection Remix ROM
( ) i m android 7.2

but I created a new gmail only for my phone. I use this email only for my friend. and proffessionally. but not financially.
I do not know if I can trust them.

@alll If you have any questions do not hesitate because French law obliges manufacturers to give us a lot of information very detailed.

As @nicole.faerber recently stated, the battery will (most likely) be sandwiched between display and PCB.
I think this can have a positive influence on the SAR in several ways:

  • some more spacing between human body and antenna
  • some absorbing by the battery
  • possibly sufficient space on the PCB to have good anntennas

eWall Mobile Phone Bag Classic, Black

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Much better solution, than trying to make a phone itself jump through all of the hurdles IMHO. Thanks for the link.