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I amplified my home's Wi-Fi with aluminum foil

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Re: I amplified my home's Wi-Fi with aluminum foil

#21

Post by 0xcde4c3db »

sarreph wrote: post #13
ohazi wrote: post #11

Earlier quoted context omitted.

speed of light / 5 GHz / 4 ~= 1.5 cm. If you can keep the size of the largest crease/feature/defect in your foil smaller than this, you should be okay.

Wow, thanks for this — I did HS-physics but much of my knowledge has since left me... :) Would love to dig into the science behind this a bit more — I don't really know where to start — i.e. why you're dividing by four. So as not to waste your time, is there a named phenomenon that you can link me to to learn more about this? Thanks again!

I don't know if there's a specific name for it, but a quarter wavelength shows up as an important feature size in a bunch of RF (and acoustic) formulas. The exact physical reasons seem to vary by context.

Re: I amplified my home's Wi-Fi with aluminum foil

#22

Post by blackguardx »

sarreph wrote: post #13
ohazi wrote: post #11

Earlier quoted context omitted.

speed of light / 5 GHz / 4 ~= 1.5 cm. If you can keep the size of the largest crease/feature/defect in your foil smaller than this, you should be okay.

Wow, thanks for this — I did HS-physics but much of my knowledge has since left me... :) Would love to dig into the science behind this a bit more — I don't really know where to start — i.e. why you're dividing by four. So as not to waste your time, is there a named phenomenon that you can link me to to learn more about this? Thanks again!

It has to do with quarter wavelength features making good antennas.

I would say that you want to be less than 1/10 of the wavelength to minimize the effect though.

Re: I amplified my home's Wi-Fi with aluminum foil

#23

Post by nugi »

niwde wrote: post #3
kleer001 wrote: post #2

Put 'em just behind the antenna like a dish aimed toward where you want to bend the signal to. It's not great, but it's cheap and easy.

Have you tried something similar before? Does it work?

I have, it is hit and miss. But was enough pf a hit to stay in use for over a year back in the 802.11b days. Grounding the reflector should also help iirc.

Re: I amplified my home's Wi-Fi with aluminum foil

#25

Post by mikestew »

sarreph wrote: post #13
ohazi wrote: post #11

Earlier quoted context omitted.

speed of light / 5 GHz / 4 ~= 1.5 cm. If you can keep the size of the largest crease/feature/defect in your foil smaller than this, you should be okay.

Wow, thanks for this — I did HS-physics but much of my knowledge has since left me... :) Would love to dig into the science behind this a bit more — I don't really know where to start — i.e. why you're dividing by four. So as not to waste your time, is there a named phenomenon that you can link me to to learn more about this? Thanks again!

As a quick off-the-top-of-my-head calculation, I take 300,000,000, the speed of light in meters/second (approximate), divide by cycles per second, you get wavelength in meters. In this case, parent calculates a quarter wavelength. A full wavelength is about 5.9cm. It’s easy to get off by an order magnitude in your head, but if through sheer repetition you know 28Mhz is about 10m, you’ll know you’re off if your 30Mhz calculation gives you 0.98m. And you can do the math from there to figure out that 14Mhz is about 20m, etc. Do it enough and you can mentally move some decimal points in your head to get a pretty good approximation for about any frequency. I learned it at some point fiddling with amateur radio, but here’s a page that I think explains it well: http://www.digitalairwireless.com/wireless-blog/t-5ghz/calcu...

Re: I amplified my home's Wi-Fi with aluminum foil

#26

Post by godelmachine »

ourmandave wrote: post #18
cipherzero wrote: post #7

Earlier quoted context omitted.

Lookup cantenna which was popular back in the day for catching WiFi from further away spots.

Saw a vid on youtube where a guy uses a metal kitchen strainer as a dish antenna for his laptop wifi out in the middle of farm field. The 'available networks' list shrinks and grows as he points it in various directions.

Would you kindly post link to that video?

Re: I amplified my home's Wi-Fi with aluminum foil

#27

Post by sp332 »

dukes_haven wrote: post #16
sarreph wrote: post #13

Earlier quoted context omitted.

Wow, thanks for this — I did HS-physics but much of my knowledge has since left me... :) Would love to dig into the science behind this a bit more — I don't really know where to start — i.e. why you're dividing by four. So as not to waste your time, is there a named phenomenon that you can link me to to learn more about this? Thanks again!

I would also like to know this. I don't know if there's a save function in h.news or not so leaving a comment

If you click through to the comment, you can "favorite" it and then it shows up in https://news.ycombinator.com/favorites?id=dukes_haven&commen... which you can also find on your profile page under "favorite comments".

Re: I amplified my home's Wi-Fi with aluminum foil

#28

Post by bonzini »

niwde wrote: post #3
kleer001 wrote: post #2

Put 'em just behind the antenna like a dish aimed toward where you want to bend the signal to. It's not great, but it's cheap and easy.

Have you tried something similar before? Does it work?

When I had my WiFi router in the basement I placed it in an aluminum oven dish, so that the reflection went towards the ground floor. It was a small but noticeable improvement.

Re: I amplified my home's Wi-Fi with aluminum foil

#29

Post by bagels »

mikestew wrote: post #25
sarreph wrote: post #13

Earlier quoted context omitted.

Wow, thanks for this — I did HS-physics but much of my knowledge has since left me... :) Would love to dig into the science behind this a bit more — I don't really know where to start — i.e. why you're dividing by four. So as not to waste your time, is there a named phenomenon that you can link me to to learn more about this? Thanks again!

As a quick off-the-top-of-my-head calculation, I take 300,000,000, the speed of light in meters/second (approximate), divide by cycles per second, you get wavelength in meters. In this case, parent calculates a quarter wavelength. A full wavelength is about 5.9cm. It’s easy to get off by an order magnitude in your head, but if through sheer repetition you know 28Mhz is about 10m, you’ll know you’re off if your 30Mhz…

300 000 000 m/s
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