Cellular antenna port on Fairphone 4

[k_o]

I’m playing around with some SDR (software defined radio) setups and since no free spectrum exists in Europe I’m trying to connect my Fairphone with a coax cable to the SDR. On other phones I have found an IPEX MHF4 connector where I could connect a pigtail to SMA connector easily to make it work. Does such a connector also exist on the Fairphone 4?

[anon9989719]

Hi and welcome to the forum.

I don’t think there is an obvious connection but this is just a user forum so best to email

support@fairphone.com

[yvmuell]

Dont understand what you are looking for but maybe you will find an answer in the schematics!?

Physically add second sim

Does this somehow help?

[const]

I’m a bit confused but intrigued about what you’re trying to do here: is the point to directly have a connection between a receiver-transmitter SDR and the phone?

Somewhat problematically for your particular case, as you can see on the circuit diagrams and parts list, the FP4 has antenna connections through springs (ANT####) instead of microcoaxial connectors; this makes disassembly easier. You could try tying into those springs, but that would be tricky to do stably.

There are also a number of switching antenna test points (all MM8030-2630), which are components J6901/02/05/07/08/09/10/11, and were, I think, put there for testing during manufacturing. These might be usable.

[k_o]

Yes, I need a direct connection. I’m contributing to Free5GC / Open5GS, i.e. open network cores and I need some test phones, to test the network core. Your hints are very helpful, I will investigate more on the schematics.

[k_o]

I see in the schematics ANT1 up to ANT7. Are these different antennas? Where can I find their purpose?

[abittner]

how about those tear down videos (or articles even, why did they vanish? ) over at ifixit they used to have beautiful detailed close ups of the different components chips PCB etc of the phones. i still find the article to the faiprhone3 at their place but i only get an 404 notfound for the fairphone4 url they used to have and archive.org has a video-article via on youtube for a rough tear down of the faiprhone4 but not as detailed as back the fairphone3 and olders in the past. what happened?

i guess you could find some info in such places and as you have stated later in this thread schematics etc. good luck with your project.

[KurtF]

It should be easy to connect a SDR radio to a phone, just use one which has an USB connector (like RTL-SDR), and connect it to the phone through a powered hub (to prevent draining your battery).

[BertG]

Do you refer to those articles?
Fairphone 4 (english)
Fairphone 3 (english)

But I am in doubt, that they are more detailed than the schematics @yvmuell linked to.
Btw., I guess, that’s something you will not see published by any other manufacturer. (Not that I could do anything with it. )

[abittner]

i didnt find the/an article that featured the detailed pictures etc such as for fp3 available at:
ifixit faiphone3 teardown article

[BertG]

Sorry, my bad.
I never checked the link on iFixIT that is labeled “Tear Down” for the FP4.
Indeed, that’s nothing like for the FP3.
Maybe they didn’t do so because it’s all in the schematics? Though they are not nearly as self explanatory and easy to asses!

[yvmuell]

ifixit explained at the beginning they will not produce a detailed teardown, there is just somewhere a YT Video

iFixit tears down the FP4 – 10/10 (again)

Finally, Fairphone partner iFixit has been able to teardown the FP4. For now, we only have a video, but I hope the photo & text version on their website’s Fairphone 4 section follows suit. I’ll add the latter here once it goes online and as soon as I notice it. [Fairphone 4 Teardown: If Only Apple Made Phones Like This…] Video transcript: Fairphone 4 Teardown: If Only Apple Made Phones Like This | iFixit News

[k_o]

Hi Kurt, thanks, but no, I need a cellular connection using the modem and the SDR is the eNb/gNb. I do not just want to plug in the USB port into the phone.