Ask HN: Does your microwave interfere with Bluetooth? Mine does

Post by jodrellblank » Fri, Oct 06, 2023, 1:50 AM UTC

ethbr1 wrote: post #91

jcrawfordor wrote: post #74

Bluetooth and WiFi both borrow their spectrum from microwave ovens. It's typical and expected that microwave ovens will cause some interference with other users of the 2.4GHz ISM band that are very nearby. Microwaves operate at very high power levels and are required to be shielded for human safety, but the permissible leakage power is relatively high compared to typical WiFi and Bluetooth devices---there's a simple…

And on the follow-up, "Why use 2.4(5) GHz for microwaves?" Because it happens to be a convenient frequency that water absorbs readily, which is the easiest way of heating up what we'd want to heat with a microwave (read: food). https://en.wikipedia.org/wiki/Electromagnetic_absorption_by_... And once we'd polluted the frequency for any stable commercial use, why not use this weird carve-out for a little thing called W…

Post by londons_explore » Fri, Oct 06, 2023, 2:58 AM UTC

ethbr1 wrote: post #97

mikewarot wrote: post #3

There's about 1000 watts of RF inside the microwave, it has to be attenuated to less than a few microwatts on the outside to avoid congestion, as they use the same frequency band. I'm amazed WiFi or Bluetooth ever works at all. 8) You can thank Hedy Lamar for that. Try cleaning the mating surfaces around the door thoroughly. If that doesn't work, consider replacing the microwave or relocating the speaker.

> Try cleaning the mating surfaces around the door thoroughly. (I'm obviously not an electrical engineer, given this is 10x stuff) If we're talking a 2.45 GHz microwave signal, that's a 12.2 cm wavelength. But I thought for shielding you only needed to have gaps of Is there some fractional-wavelength propagation, or is my understanding of EM shielding off-base? How are microwaves noisy? E.g. https://physics.stackexch…

Post by londons_explore » Fri, Oct 06, 2023, 3:03 AM UTC

itishappy wrote: post #102

ethbr1 wrote: post #97

Earlier quoted context omitted.

> Try cleaning the mating surfaces around the door thoroughly. (I'm obviously not an electrical engineer, given this is 10x stuff) If we're talking a 2.45 GHz microwave signal, that's a 12.2 cm wavelength. But I thought for shielding you only needed to have gaps of Is there some fractional-wavelength propagation, or is my understanding of EM shielding off-base? How are microwaves noisy? E.g. https://physics.stackexch…

> Is there some fractional-wavelength propagation? "Propagation" is probably not the right word, but fractional wavelengths can "leak" some amount of field. https://en.wikipedia.org/wiki/Evanescent_field

Post by londons_explore » Fri, Oct 06, 2023, 3:14 AM UTC

callalex wrote: post #61

kpozin wrote: post #12

My data is anecdotal, but I've observed that Panasonic inverter ovens that I've used interfered in the 2.4GHz range, while models of other brands (e.g. GE) have not. (This is unfortunate because Panasonic seems to be the only brand that can actually adjust power output, whereas the others simulate lower power levels by cycling on and off.)

You can thank terribly written intellectual property laws for that exclusivity. It’s not like inverters are some kind of new technology, and yet here we are.

Post by a_t48 » Fri, Oct 06, 2023, 3:19 AM UTC

takinola wrote: post #80

There's a particular spot on a local highway that interrupts my wireless CarPlay connection if I spend too long in it (eg when traffic is slow). It's right next to an exit with a bunch of buildings (including a hospital) so I'm sure there is some massive emitter in one of those buildings. I'm still at a loss about what could cause that kind of interference inside a major city and still be legal.