Hi,

I’m looking for some help in a field that is super technical and I don’t fully understand.

I’m planning on using a bunch of these seeed studio Esp modules for some home automation projects, especially because they have a lipo battery charger making it great for portable stuff.

The thing is the the ESP32s have U.FL SMD antenna connectors. Most of the antennas that you can buy with U.FL connections while are reasonably small, come with 50-150mm leads, which sort of makes the small size of the module a little less valid.

What I’d like to do is get a female U.FL SMD connector and make a small daugherboard with an 2.4GHz SMD antenna on it, for instance a Janson 2450AT42B100 or a Molex 479480001.

They go over the circuit board requirements quite thoroughly so I don’t think designing it will be too difficult, but what I don’t know is, they say that you need impedance matching on the circuit, and I see that there appears to be something that looks like it on the ESP circuit diagram, but I’m not actually sure if it is or not:

You can see it in the middle near the bottom of the diagram here: Seeeduino-XIAO-ESP32C3-SCH

So my questions are:

1: Is this a dumb idea, having a direct plug-on SMD antenna?

2: Is that an impedance matchning circuit between LNA_IN on the ESP chip and U.FL-R-SMT-1?

3: If I can’t get a female U.FL SMD connector, would using one with a lead and shortening it to make the daughterboard able to be much closer to the connector affect anything? Do I need to ensure that the lead length matches the wavelength at all?

Edit: Found this SMD female U.FL, so they do exist.

  • elmicha@feddit.deEnglish
    4·
    1 year ago

    Is this not the same ESP32 with an antenna? Although I don’t know how the nRF52840 from your question comes into play here. Don’t you normally use an ESP or an NRF, and not both at the same place (with the exception of a gateway maybe)?

    • KyuubiNoKitsune@lemmy.blahaj.zoneOPEnglish
      3·
      1 year ago

      The nRF was a useless inclusion tbh, sorry for the confusion. The nRF already has an smd antenna.

      The thing with those antennas is the size of the antenna vs the size of the module, it’s almost twice the size, negating any benefit of having such a small module.

      Hence my desire to use an SMD antenna on a small board instead.

      • elmicha@feddit.deEnglish
        3·
        1 year ago

        So you have these boards already? Or could you just get other boards with an ESP32 and LiPo charger? Because many already have a printed or ceramic antenna built-in.