How to add an external antenna to an ESP board

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:

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Nice job, does the external antenna make much difference?

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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.

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This sensor is surrounded by metal (sink and dishwasher).

It’s working and that’s the main thing. :slight_smile:

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.

Cant see your image @FunkyBoT

I found the information online.

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Nice work Tom! I may need to use this approach when I build my letterbox node :slight_smile:

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.

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Thank you! Works well!

Proof of performance boost. Exact same location in my lawn boosted this mi-flora BLE sensor from -90 to -65dBm. It’s not a little antenna though.

Screenshot_2019-11-17%20Home%20Assistant

Also worth pointing out that this is kind of illegal. Now that the device’s effective radiated power has changed the FCC certification is no longer valid.

In this case it’s probably ok as it is a long way from my property boundary and the signal drops off to the noise floor before it gets there.

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Does anyone have experience with adding an external antenna to a Wemos D1 Mini (non-Pro)?

Scratch away some of the insulation from the on-board antenna. Connect the signal/core of your coax to this point using solder, and be very short/neat about the connection. Connect the shield/ground of the coax to GND on your board. There ya go!

A nodeMCU wasn’t connecting at all in my shed so I tried attaching an aerial from an old router I had laying around.

Baseline as stock, upstairs.

With aerial, upstairs.

With aerial in the shed. Sorted!

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I modded a MagicHome RGB LED strip controller tonight and embedded it inside the metal case of a cheap RGB led floodlight.
Rather than cut the antenna cable, I scraped away the solder mask on the antenna trace, and the ground plane and added a surface mount UFL connector.

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Wow. That’s fiddly work.

After I (succesfully, mind you) modded a standard D1 Mini with an antenna flylead, I now use D1 Mini Pros when I need an external antenna, as that already has the socket in place. Still need to move a super-tiny 0603-size zero ohm resistor from one set of pads to another though.

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Did you measure the signal before and after the mod? What kind of results did you get?

I have been doing more research on this and on the board you have both traces are connected. So, ‘the experts’ are claiming that you need to connect one wire of the external antenna to ground on the board and the other wire of the external antenna to the antenna trace on the board. Do you have any comments about that?

Thanks for your posting

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