A Beginner's Two-Component Crystal-Style Wi-Fi Detector
Key topics
A DIY Wi-Fi detector project has sparked a lively discussion about microwave oven interference, with some users sharing their own experiences of Wi-Fi degradation when their microwaves are in use. Commenters are divided on whether this is a cause for concern, with some pointing out that a malfunctioning microwave's radiation leakage could be the culprit, while others downplay the risk, citing legal requirements for microwave emissions. One practical solution proposed is to switch devices to 5Ghz Wi-Fi to avoid interference, although others note that many non-computer devices still only support 2.4Ghz. As users share their own network configurations, the conversation highlights the ongoing relevance of Wi-Fi interference in our increasingly connected lives.
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Dec 31, 2025 at 8:00 AM EST
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A friend of mine has a microwave that noticeably degrades his wifi when it is in use.
Edit: I see no reason this wouldn’t work, however?
I had to put the phone close to the microwave to detect this. The degradation was obviously stronger when the phone was closer.
If your friend experiences noticeable degradation regardless of the distance within the room, it might be worrisome.
But I think it's normal to have some interference. That doesn't necessarily mean enough of the 2.4 GHz radiation escapes the microwave to be harmful to an animal, as Wi-Fi, Bluetooth and so on are very weak, comparatively.
Funny thing is, after putting my phone inside a closed turned off microwave, it got Wi-Fi, although very weak. I didn't try that with all the microwaves, but with 2 or 3 of them.
I think the Faraday cage around the microwave was built to be good enough for safety, but it wasn't built with Wi-Fi interference in mind.
Disclaimer: I might be wrong, as I don't have enough background to make any bold claims.
Probably not. I recall calculating it once, and the legal requirements for microwave oven shielding still allow it to produce a few watts of 2.4Ghz leakage. This is contrasted to 50mW typical WiFi AP power, and 5-50mW BlueTooth powers.
A few watts is totally non-dangerous to humans, especially diffused across the entire door.
On 2.4 GHz in the US you're allowed up to 36dbm, 30 of that can be transmitter, the remaining 6 can be a higher gain antenna.
(I imagine it's a much lower cost to only handle 2.4GHz?)
The 16 are 4 computers (2 Macs, a Surface Pro 4, and an RPi 4), 3 mobile devices (iPhone, iPad, Apple Watch), 3 media devices (Fire TV, Nintendo Switch, and Kindle Oasis), one smart plug, a Brother printer, 3 smart speakers (Google Home Mini, two Echos), and an EV charger.
They have am much lower current and voltage requirement, so might me more sensitive. You can also do tuning to use different sized antenna. However that strays into analogue eletronics, which I've not really touched for 15 years.
"you can build a tiny “crystal detector” that responds to 2.4 GHz Wi-Fi, Bluetooth, and even microwave oven leakage"
[1] https://datasheet4u.com/pdf-down/H/S/M/HSMS-2862_AgilentTech...
Really wish I was clever enough to do electronics!
This sort of thing is definitely why I come the HN.
See Dipole Calculator: https://www.omnicalculator.com/physics/dipole
And you need a faster diode.
https://en.wikipedia.org/wiki/Energy_harvesting
high-speed [1N5711] Schottky diode
and an LED — you can build a tiny “crystal detector” that responds to
2.4 GHz
Wi-Fi, Bluetooth, and even microwave..."
That is interesting!
I never knew that a Schottky diode could rectify at 2.4 GHz -- that's pretty darn impressive!