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LilyGO / TTGO-T8-ESP32

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Hows to use IPEX antenna #20

Open pidou46 opened 3 years ago

pidou46 commented 3 years ago

Please, could you give instructions how to use IPEX antenna instead of 3D antenna built in ?

dgoadby commented 3 years ago

The circuit diagram shows two 0 ohm resistors (aka links). To use an external antenna via the Apex socket you need to remove R11 and add a link to R10. Note: not all of my LilyGO's have the Apex socket fitted. If the Apex socket is not fitted then the pads are usually there to add one. Here is a useful link for a different board but the idea is the same: Using the Apex antenna socket

pidou46 commented 3 years ago

Thank you for your answer.

I have two board with different revision. For one of it it's obvious I see the circuit make a Y and it's easy two understand wish resistor need to be removed and where to make the link.

But for the second one, there is a bunch of 4 resistors and I'm unable to identify wish one to remove and where to solder! I try to make a picture but failed to get a nice one.

I suggest for the next release, that you add it on the pin layout to avoid recurrent questions about it.

pidou46 commented 3 years ago

My board is T8 V1.1 Here is what I think I have to do: image Are you agree ?

dgoadby commented 3 years ago

Well, it doesn't look logical but the PCB tracks may not be going in a logical way. I am expecting that you will need to remove one link and add another. All of the circuits that show an Ipex option have the same configuration with one jumper to remove to the existing PCB antenna and one jumper to add to connect the same point to the Ipex centre pin.

esp32-apex

I have just looked at the ESP32 documentation for an Ipex antenna. The diagram is below and the critical things to note are the two capacitors and an inductor. The LilyGo board does not have the inductor but has a capacitor in that location. Also, in the LilyGO circuit there are two capacitors shown as NC as well as the R0 resistor (aka link). The implication is that the components marked NC are left off for the on-board antenna and they should be added for an Ipex antenna.

esp32-1

My gut feeling is that I don't think that your changes are correct. If you use a meter you should be able to find which link goes to the on-board antenna and which pad goes to the Ipex socket. Removing the one and adding the other would be the way to go but the two capactors probably require adding as well.

The problem with antenna at these frequencies is they need matching to the source. If the matching is not correct then you might as well use the on-board antenna. The circuit from the ESP32 manual with an inductor and two capacitors is a pi match. The version on the LilyGO board is not. It is a pity that there is no information from them.

I will research this some more as I too need to use an external antenna. For now I hope that I have been of some help.

visicon-masc commented 3 years ago

I will research this some more as I too need to use an external antenna. For now I hope that I have been of some help.

Any news on this topic? Has anyone any expirience in using IPEX antenna without populating C17 and L4? Has anyone gained information about values for C17 and L4 for correct matching? (Talking about v1.7)

LiveRock commented 3 years ago

I asked my supplier and he said only a resistor bridge is needed. I tried but it does not work. I am asking him to double check with the manufacturer. Thanks

heol-files commented 2 years ago

Any news on this? After looking at my boards the above suggestion that I have to add extra capacitors/Inductors after moving the link R16 -> R23 seems to be the way to go to me. And change C18 to match the 2nd schema maybe?

LiveRock commented 2 years ago

@heol-files Did you add extra capacitors/inductors? Or, just move the R link? Did it work?

heol-files commented 2 years ago

@LiveRock Have not tried it yet, missing components. But I have IPEX connectors so I will try mount one on a TTGO T7_V1.4 instead and move the link R15 -> R14 to see if that works. Last picture in this thread: https://github.com/LilyGO/TTGO-T7-Demo/issues/3

visicon-masc commented 2 years ago

I have several T8 boards here and did a quick camparism: external antenna produces way worse RSSI than the soldered "3D antenna"... :-( And yes, I switched the "link" to IPEX.

Has anyone similar expirience or even new insights?

Bye, Marc.