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Making a GSM antenna?

Posted: Wed Jan 24, 2018 12:37 pm UTC
by somitomi
Insert classic backstory: moved to new place, terrible phone reception due to thick walls, dropped calls, yadda-yadda.
Apparently the reception in the yard outside my window is slightly better, so I have this idea of making two identical antennas connected by coaxial cable and placing one of them outside and the other inside the wall. However this is based on a very rudimentary understanding of radio waves and antennas, which isn't enough to decide what type of antenna is best for this job (I'm thinking of a dipole or loop dipole because they are simple to make).
Another idea I have is connecting an antenna directly to the phone itself. If I recall correctly, the gold circlular things marked L1 and L2 on this pic are antenna connections, but I couldn't find out what they are called:
IMG_5380[1].JPG

I read that simply pushing the end of a short wire can improve reception, but I'd like my solution to be a little less crude.

Re: Making a GSM antenna?

Posted: Thu Mar 08, 2018 11:00 pm UTC
by somitomi
A few updates on this project for the zero people intersted in it.
Firstly a word of WARNING: the connectors are indeed antenna connections, apparently used to connect testing equipment in the factory. According to some forum posts they disconnect the internal antenna when something is plugged in and are designed for a very limited number of connections. Read: they're self-destruct buttons in disguise. :oops: :evil:
On the plus side, connecting the large dipole directly to the phone that way works superbly if you manage to get a reliable contact at the connector. Which you probably won't without a matching male counterpart. This type of connector is called "MHC-705" by the way.
Testing of the dual antenna setup is pending, I'd really like to sort the damage I caused to my own phone first.

Re: Making a GSM antenna?

Posted: Thu Mar 08, 2018 11:11 pm UTC
by Jplus
Actually, I'm interested in this project. Just don't expect me to reply anything meaningful in here, because I understand nearly nothing about antennas. But hey, go you!

Re: Making a GSM antenna?

Posted: Sun Mar 11, 2018 10:53 am UTC
by somitomi
Jplus wrote:Actually, I'm interested in this project. Just don't expect me to reply anything meaningful in here, because I understand nearly nothing about antennas. But hey, go you!

Yeah, go me, I actually managed to fix my phone by replacing the connector with a short length of wire despite ripping a solder pad off the PCB in the process. Seriously kids, stay in school and don't mess with this connector.
Mess with the internal antenna connection hiding under the backplate, which seems to be more durable and using a standrdised connector. It's rather small and probably not designed for a large number of connections either, but if I can get the matching connector I can test my antennas more thoroughly.

Re: Making a GSM antenna?

Posted: Sun Mar 11, 2018 8:50 pm UTC
by hotaru
somitomi wrote:Mess with the internal antenna connection hiding under the backplate, which seems to be more durable and using a standrdised connector. It's rather small and probably not designed for a large number of connections either, but if I can get the matching connector I can test my antennas more thoroughly.


is it one of these?
https://en.wikipedia.org/wiki/Hirose_U.FL
Image

if so, they are "are not designed with reconnection in mind, and they are only rated for a few reconnects (approximately 30 mating cycles) before replacement is needed."

Re: Making a GSM antenna?

Posted: Mon Mar 12, 2018 6:44 pm UTC
by somitomi
hotaru wrote:
somitomi wrote:Mess with the internal antenna connection hiding under the backplate, which seems to be more durable and using a standrdised connector. It's rather small and probably not designed for a large number of connections either, but if I can get the matching connector I can test my antennas more thoroughly.


is it one of these?
https://en.wikipedia.org/wiki/Hirose_U.FL
Image

if so, they are "are not designed with reconnection in mind, and they are only rated for a few reconnects (approximately 30 mating cycles) before replacement is needed."

It might be, looks very similar, which is bit of a shame. But it already proved more reliable for me, having survived about 10-15 mating cycles in the past few days. That being said, I'll probably test my antenna once and then leave it at that. I fear adding a permanent external antenna connection might prove detrimental to everyday use, as cool as it would otherwise be.

Re: Making a GSM antenna?

Posted: Thu Mar 15, 2018 1:27 pm UTC
by somitomi
somitomi wrote: I have this idea of making two identical antennas connected by coaxial cable and placing one of them outside and the other inside the wall.

A little update on this idea: I tested it today and got no signs of it working as I thought it would. This is probably because I didn't pay too much attention to impedance matching between the antenna and the cable since I know jack about how that works. And it's not like the courtyard has perfect reception anyway, so considering the effort needed to make this work (and install it permanently), I decided to abandon this branch of the project now.

Re: Making a GSM antenna?

Posted: Thu Mar 15, 2018 2:43 pm UTC
by hotaru
somitomi wrote:
somitomi wrote: I have this idea of making two identical antennas connected by coaxial cable and placing one of them outside and the other inside the wall.

A little update on this idea: I tested it today and got no signs of it working as I thought it would. This is probably because I didn't pay too much attention to impedance matching between the antenna and the cable since I know jack about how that works. And it's not like the courtyard has perfect reception anyway, so considering the effort needed to make this work (and install it permanently), I decided to abandon this branch of the project now.

there are amplifiers that would probably work, but they're kinda expensive: https://www.wilsonamplifiers.com/home?menu

Re: Making a GSM antenna?

Posted: Tue Mar 20, 2018 9:53 am UTC
by somitomi
hotaru wrote:there are amplifiers that would probably work, but they're kinda expensive: https://www.wilsonamplifiers.com/home?menu

Yeah, that's not exactly the sort of money I'd spend to fix a minor inconvenience.