ESP32-C3 SuperMini antenna modification

Posted by ta988 1 day ago

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Comments

Comment by bArray 1 day ago

Antenna design is a dark art, I like simple hacks like this.

> The two parts of the antenna are intentionally designed to create an omnidirectional radiation pattern without a pronounced directionality.

I worked on a project a while back to try to utilize this to detect the arrival direction of WiFi signals approximately based on received strength. Do this for enough base stations and you have a very crude positioning system.

Comment by TGower 21 hours ago

I'm doing something similar, using the directionality of the antenna to turn an ESP32 into a high RPM gyroscope for use in a combat robot. Standard gyro chips top out well under 1000 RPM, and are much more expensive than an ESP32 board, plus the ESP can serve as the radio control link and brain of the bot at the same time.

Comment by Joel_Mckay 23 hours ago

It also immediately invalidates FCC modular component compliance, and may be illegal if operating on dual-use bands like 5G wifi.

Remember the rules limits use the ERP, and EEs may have added a crappy antenna on purpose to meet the legal limits.

https://en.wikipedia.org/wiki/Effective_radiated_power

There are also medical radiofrequency exposure guidelines, and they mitigate deep tissue burns or "G5 Mind control beams" concerns. lol =3

https://www.canada.ca/en/health-canada/services/health-risks...

Comment by spacedoutman 23 hours ago

You can just ignore the FCC.

They are completely toothless.

Comment by chemeril 22 hours ago

As an individual this is mostly true unless you're touching broadcasting proper. As a business this is absolutely not true and noncompliance is a ticking time bomb that will bankrupt you.

Comment by bikezen 20 hours ago

As someone in Southern California who uses HAM, this is both true and not true. There's an older gentleman who has already spent time in jail for sitting on frequencies without a license repeatedly. After he got out, he jumped right back on it. He's got tens of thousands if not more in unpaid fines, but as far as I'm aware they cant get blood from a stone.

Another anecdote, dozen or more years ago a friend had a fault cable modem that was spitting out radio traffic I assume on some important frequencies in a dense area. They got a knock on the door from an FCC team who were tracking the interference down.

Comment by ikidd 15 hours ago

HAM-is-not-ham

And your example must be one of those weirdos on 80m. What a pack of crazies.

Comment by jubilanti 17 hours ago

The author is German and lists German contact information. They're a lot stricter in the EU about this.

Comment by 22 hours ago

Comment by vkdelta 23 hours ago

Exactly… they would have added crappy antenna as they likely meet emission, spurious or harmonics requirements..

Engineer might be messing with other 2.4GHz devices by doing this

Comment by dgacmu 20 hours ago

This seems very unlikely compared to the obvious answer that they added a crappy antenna to keep their BoM and assembly costs low.

The radios on these are weak and adding an Omni antenna is exceptionally unlikely to violate EIRP.

Could this design accidentally radiate something it's picking up from the board outside of 2.4ghz? Sure.

But practically it's quite unlikely to in this context.

Comment by tylerflick 22 hours ago

2.4GHz is already incredibly crowded and prone to interference (in urban environments). I remember once picking up emissions on a Bluetooth headset from a leaky microwave oven.

Comment by sscaryterry 15 hours ago

That isn't how this works. There is no change in emission power, the antenna doesn't add power.

Comment by BenjiWiebe 11 hours ago

Well mostly true.

You can replace an inefficient (turns power into heat) antenna with a more efficient antenna which will then radiate more.

And some frequencies are regulated by effective radiated power, where they basically care about the strength of the signal in the strongest location, so a more directional antenna could push you over the limit.

Comment by wolvoleo 14 hours ago

The antenna on these cheapo modules is bodged anyway. They don't get a good signal out and it's not just because of the size. I have other modules from waveshare that use the same antenna and they work way way better.

So yeah I also do this if I really need the WiFi or Bluetooth. Usually I don't though.

Edit: oh I see he goes into that later. Like the way they don't leave a copper free space around the antenna. Exactly. They are a bit compromised but they are so so cheap.

Comment by minimaltom 20 hours ago

Silver-coated wire? I don't have that lying around.

Comment by fluxflexer 19 hours ago

Nothing special about it. https://amzn.eu/d/06dMTm5c

Handy to garrot werewolves too

Comment by minimaltom 11 hours ago

Hell yeah!!

Comment by DarkStar851 2 hours ago

Paperclip has worked fine in my experience. I've got a bunch of these and the stock antenna really is just awful.