[ifh-hn]

So the question is how to do similar for 5ghz?

[avidiax]

Faster diode, like HSMS-2850 [1], and different leg lengths (tune for 5Ghz).

[1] https://datasheet4u.com/pdf-down/H/S/M/HSMS-2862_AgilentTech...

[ifh-hn]

Thanks. Appreciate the reply. From a brief look that might detect 2.4ghz too?

Really wish I was clever enough to do electronics!

[avidiax]

Depends on the length of the antenna. I'd bet you can get a length close enough to be a quarter-wave 5Ghz and 1/2-wave 2.4ghz antenna. Just buy a 2.4/5Ghz combo antenna and slap the diodes across it.

[ifh-hn]

I love simple solution like this. It'd be cool just wandering around being able to detect mobile and stuff with a tiny led.

This sort of thing is definitely why I come the HN.

[pixelpoet]

Just curious, what does your username stand for? :D

[ifh-hn]

Nothing. obviously the last bit stands for hacker news. Just randomly pressed letters.

[ninalanyon]

For 2.4 GHz each leg of the antenna should be 30 mm. For 5 GHz just under 15 mm.

See Dipole Calculator: https://www.omnicalculator.com/physics/dipole

And you need a faster diode.

[cluckindan]

Shorter antenna and faster diode. A Schmitt trigger would allow for much more sensitivity, but it would not be a passive device (requires a power source)