this post was submitted on 12 Sep 2023
1261 points (97.7% liked)
Memes
45625 readers
1375 users here now
Rules:
- Be civil and nice.
- Try not to excessively repost, as a rule of thumb, wait at least 2 months to do it if you have to.
founded 5 years ago
MODERATORS
you are viewing a single comment's thread
view the rest of the comments
view the rest of the comments
I'm about 62% sure this is a joke...
Please help, I'm clueless about this kind of stuff.
Look up the DIY parabolic reflectors people used to use on their WiFi antennas, they did actually work! I used one and recorded a marked improvement in WiFi strength at the furthest point in my home that was previously a low connection quality spot.
Radio waves come out of an antenna and just go in every direction, so a router against your outer wall is wasting a lot of its energy just directed into the neighbour's house. If you can reflect some of that back in, you get improved signal reception. It's very cool :-)
But if waves transmit information, and the same information comes at all sides, won't the signals that bounce off the reflector arrive after the waves with a direct line and thus transmit redundant information?
Yes. They will.
When creating a reflector, you want to place it a specific distance from the focal point, so the waves are in sync with the waves going direct to the device, they will be offset one or two full wavelengths, but that hardly matters. About a half wavelength away from the emitter/antenna is ideal.
There's also a way to calculate the parabolic arc you want to make the signal very directional (the way a satellite dish works, but in reverse. Those dishes collect and concentrate the signal, in this case you want to redirect the emission in the same direction - think about it like a flashlight, where the majority of the light is in a small cone in the middle, but there's still some light going everywhere that isn't blocked by the mirror reflector dish in the flashlight).
There's a hundred different ways to get this done, tons of antenna designs to work with, but in general, wifi uses beamforming, which is a method to use multiple antennas that are transmitting the same signal, but they have the exact waveform slightly offset from eachother, which makes the signal much stronger in the complementary direction. It basically generates a beam the hard way. Wifi has gotten very good at doing this, so reflectors and directors, and all that fancy antenna design stuff isn't really required.
The only real improvement to be made, given wifi's current complexities, is to put in larger antennas; most wifi antennas are quarter wavelength or often smaller.... "Upgrading" to well matched full wavelength antennas may yield some benefit, but there's a lot of nuance there too. It's a deep subject so I'm just touching on how things go. I find it fascinating, I'm sure not everyone does.
Waves can bounce off of everything, wifi/Bluetooth/cellular automatically compensate for this effect. There is a lot of signal processing involved with wireless data transmission to filter noise and correct errors. This is part of the reason why it's taken decades to reach this level of wifi speeds and why Bluetooth has a real hard time matching wired audio.
I have one against an outside wall to get service in my standalone garage. Success.
I think mirror won't work, but this might:
It's the same principle of al satellite dish and it works, but I'm 86% sure that mirrors won't affect wifi, so we're still not at 100% but getting there.
Depends on what frequency your "mirror" mirrors.
A traditional one reflects higher frequency of electromagnetic rays (visible light) than what you need for wifi (in the microwave frequencies)
So you're saying the walls of an old microwave might do the trick
Jokes aside, anything made of metal will be a good enough reflector for most consumer use.
A coke can cut vertically in half makes a great parabolic relfector. Pepsi can maybe. Dr pepper not recommended.
Actually yes.
Microwave ovens work by exciting water molecules using many hundreds of watts of ~2.45 GHz microwaves.
This specific frequency has a heating effect on water, so when you blast enough of it at food, which is often very saturated with water, it will heat up. The heat energy will transfer to the rest of the molecules in the food by contact.
That's the general idea at least.... I'm sure there's more interactions that happen, water is just the most significant, to my knowledge.
So the protection in the microwave is capable of reflecting (for the purposes of containment) 2.4Ghz microwaves very well, and bluntly, does a good job with many other radio waves too, across a pretty broad band of frequencies.... so the material that makes up the protective chassis of a microwave is ideal for making a reflector for wifi, since it was constructed with the idea of reflecting 2.4Ghz frequencies. Microwave ovens create the signal fairly crudely with a magnetron, but the underlying concepts are the same.
If it's a silver layer on a glass/plastic pane (like basically any mirror) and it's big enough (more than idk, let's say 20 cm to be safe) why wouldn't it mirror the lower frequencies too?
Not enough interaction with the waves.
I'm not fully versed on all the physics of it, but to my understanding, the layer of silver that makes up the reflective surface of a mirror is crazy thin, like, less than the thickness of paint.
The basic concept I was explained is that the longer the wavelength (lower frequency) the easier it is for it to penetrate obstacles, specifically things that are relatively opaque to radio waves. The very high frequency (small wavelength) waves of light, are so small that almost everything interacts with them; so when they make it to the silver layer, despite that silver layer being impossibly thin, the >100THz waves, will bounce. When dealing with stuff that's much lower frequency (like 2GHz to 5Ghz, many orders of magnitude lower frequency), there's not enough of the material to interact with the wave to have any significant effect on its propagation, so it passes right through.
This is a good observation and a great question. I'm sorry I couldn't be more specific, I'm just not as well versed in the physics of it all to really get into the details; but I hope this helps.
Oh yeah probably but it might absorb some or even more thant it reflects
So, wifi is made up of radio waves, specifically micro waves, which are all sub-classifications of electromagnetic waves.
There's another common electromagnetic wave you've certainly heard of: visible light.
While the wording is a bit awkward, the previous poster isn't wrong. Just, in radio, it's referred to as a reflector, not a mirror. Same principle, different area of technology.
EM is incredibly interesting especially since all data communication, with the exception of copper wires, is EM. Fiber optic is light, which we've established, is EM, and wifi is radio, which is also EM. Apart from the copper in your ethernet/DSL/Coax cable, it's all EM. It's fascinating to me that we use EM for so much, and fiber is considered the pinnacle of data connections, yet, light propagates slower through glass than radio propagates through the atmosphere, so technically, wifi can get a signal from A to B faster than fiber can.... and we put that stuff in our house.
All EM is at, or near, the speed of light. Glass, used in fiber, tends to slow the light down about 30% or so.... that's fascinating because the internet is largely fiber, and so the information for this or anything else on the internet is being delivered to your device at, or very near the speed of light.
Anyway, I'm off topic. I'm just a gigantic nerd about this stuff.