Hacking WiFi antenna on ESP32 - Page 1
Forum section: electronics / rf-microwave

author: HarryDoPECC
author_rank: Regular Contributor
timestamp: May 26, 2025, 02:31:53 am
content: Background: I'm fairly heavily invested in certain ESP32 based boards for automating irrigation and things on my farmstead, so changing boards is undesirable. Its an isolated rural environment, I'm comfortable that interfering with FCC certified designs will not have impacts outside the boundary, so am willing to live with those impacts.The issue is that some of the boards have had marginal WiFi signal, this was manageable until we recently put up some high wire mesh fences to keep the pests out, and the partial Faraday cage seems to have knocked the signal down enough to give unstable connection. The access point is decent and I thought that the ESP module's antenna may be a more fruitful place to look for improvements.The ESP community has already been in this space and I find two common mods: adding a connector for external antenna or hacking the PCB antenna for allegedly better performance. See pics. These modules have an F-antenna with meander pattern - the feed and ground are visible in one pic and the green wire in the pic shows the original antenna patternMod 1 is to disconnect the PCB antenna and add an external instead. Pics of exposed connections and soldered leadMod 2 claims to extend the antenna from 1/4 to 1/2 wave with generally improved results, especially after tweaking orientation and length. Wire antenna added following the original meander and extended off-board. Original antenna left intact.I'm a digital/linear guy and my RF is far in the past. I'd appreciate any general comments from the microwave sorcerers as to the general likelihood of 1 or 2 being useful, and a punt on which may be more likely to be useful. (I'm attracted to 2 for simplicity)Thanks in advance

author: Smokey
author_rank: Super Contributor
timestamp: May 26, 2025, 02:43:31 am
content: um...1) I think the holes in a fence would have to be smaller than about 1.25cm to have any appreciable attenuation of 2.4GHz Wifi. So your fence probably isn't acting as a "Faraday Cage". It's probably also not fully enclosed.2) They already make all those ESP32 modules with external antenna connectors:https://www.digikey.com/en/products/detail/espressif-systems/ESP32-WROOM-32UE-N4/11613136[]Just the first random google image result:https://www.elecbee.com/en-73350-esp32-wroom-32u-wrover-wifi-module-with-2-4g-antenna-development-board?gQT=2

author: HarryDoPECC
author_rank: Regular Contributor
timestamp: May 26, 2025, 03:16:24 am
content: Thanks, yes 20mm mesh so I thought some attenuation likely. Enough to push me from marginal into trouble. As I said, I have a few boards that are heavily plumbed in and the ESP32 is in turn attached to those boards. So I could change the ESP submodule, but if I am going to hack with the module I was tempted to try an antenna hack first.Hence looking for some advice as to how sensible these hacks look to the uwave people.

author: Smokey
author_rank: Super Contributor
timestamp: May 26, 2025, 03:41:33 am
content: The modules with external antennas are $7.50.. With the antenna and cable...

author: Poroit
author_rank: Frequent Contributor
timestamp: May 26, 2025, 07:07:53 am
content: G'day HarryDoPECC,An external antenna will certainly improve the range and those PCB's that@Smokeyhas suggested are probably way more cost effective than trying to retrofit an external antenna connector to the existing.Do you get many failures due to water damage?(attached)

author: tooki
author_rank: Super Contributor
timestamp: May 26, 2025, 07:32:15 am
content: Quote from: HarryDoPECC on May 26, 2025, 03:16:24 amModifying an existing module without an antenna connector (or at least without the solder pads for one) makes no sense. Especially given how fickle microwave radio is. (For example, a little bit of overhang on your antenna wire could act as a filter.) Just buy a module like the last image in Smokey’s reply.I’ve used that kind of module in several projects where I used an all-metal enclosure and thus would have had awful performance with an internal antenna.With the external antenna connector, you can then do things like using a large antenna, or one mounted in a better location.

author: A.Z.
author_rank: Super Contributor
timestamp: May 26, 2025, 08:32:55 am
content: Why don't you use LoRa board ? The antennas in such a case may be some relatively small/simple (and homebuilt) collinear or J-Pole and to further extend coverage, if needed, you may just add "repeater" nodes

author: HarryDoPECC
author_rank: Regular Contributor
timestamp: May 26, 2025, 11:12:55 pm
content: Thanks all, good suggestions for next steps.I’m still wondering if the hacks I have found may save me the need to take those next steps like replace the soldered ESP32 modules or change technology. I know they are ugly hacks but potentially so much easier than the proper solutions. In my area of expertise I can assess hacks as 1) ugly and uncertain but worth a try, or 2) nah, based on misconception, almost certainly waste of effort.I’m hoping someone with uwave experience could guide me between 1) and 2) on these hacks.Poroit: pics are not my gear, are illustrations of the suggested hacks. And yeah I see now that one of those boards looks like it’s developing a worse problem….

author: Smokey
author_rank: Super Contributor
timestamp: May 26, 2025, 11:21:19 pm
content: Quote from: HarryDoPECC on May 26, 2025, 11:12:55 pmDude.. Here you go. I think this is what you are looking for....I'm a "uwave expert". Your "idea" is amazing! you have my permission to solder wires anywhere you want. Actually if you solder like 4 wires I bet it will work 4x better. I guarantee it will work 103% of the time... It will increase your wifi signal strength, your length and your girth...or...You can listen to everyone that has replied here and just spend the $8 for new modules with external antennas, which should drop in to your existing stuff.

author: HarryDoPECC
author_rank: Regular Contributor
timestamp: May 30, 2025, 10:58:25 pm
content: Thanks all for your input. These ESP32 modules are built onto boards that are common in the automation community, WiFi signal problem are not uncommon and the two hacks above are floating around as suggested responses. I brought them here for opinion if either were likely to be useful. Since this forum is pretty well indexed I hope this information may be available to others in the automation community.My conclusions:- the "extension" with the green wire shown above belongs in the group of "misunderstands principles of slot/aperture antennas" So not a useful thing- hacking an antennal lead is the Wrong Way to do the Right Thing which is to replace the module with one having a properly engineered antenna connector. If this is truly impossible then adding a lead *might* be helpful but don't expect predictable or best results.Thanks again, I think we can call this done.