If you’ve purchased an ESP board without a connector for an external antenna and find you are pushing the limits of reception - all is not lost.
Also this is slightly easier than moving the 0603 sized resistor required to use the external antenna socket on some boards.
These parts can be found for a couple of dollars on ebay or Aliexpress:
Then do this:
Good to go:
Nice job, does the external antenna make much difference?
This was for a new project that I thought might be a bit ‘iffy’ signal strength wise but unfortunately I did not do a baseline test without the antenna first. I can say it is working well.
This sensor is surrounded by metal (sink and dishwasher).
It’s working and that’s the main thing. 
I did try something similar on a PiZero and actually found the external antenna gave less signal strength but I think it’s because the SMA lead I used was really long! Luckily I was able to reverse my mods, and the PCB antenna was good enough.
This could be really handy method for mounting ESP modules inside metal appliances also, just make a small hole for the SMA connector.
My NodeMCU has a different antenna layout similar to the one of the picture below. Do you know how to do it in this one?
Yeah keep the leads short. RG178 coax has a bit under half power loss (2.6dB) per meter at 2.4GHz.
Nice work Tom! I may need to use this approach when I build my letterbox node
I tried this approach but had mixed results in the end I used a D1 mini pro with its external antenna connector
Results will depend on the antenna used and the length of connecting coax.
I’ve got some more boards on the way from China and will do a before/after test next time.
Just wanted to add one more:
I found a TYWE3S module in a Tuya plug and replaced the PCB antenna with an external one. The approach is basically the same as in @tom_l’s original post, but the PCB antenna is mirrored on the TYWE3S.
I don’t have a before-after comparison. In my case the plug is used behind the pool where there is absolutely no Wifi signal, but with the above modification I could install an external antenna about 1 metre above the pool water level and ESPHome now reports around -72 dB signal strength.
