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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

#81

Post by NicoJuicy »

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

It will dissapear more slowly here: http://handlr.sapico.me/Home/ByTag?Name=diy :p ( unfinished webapp)

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

#82

Post by jacquesm »

arghwhat wrote: post #56

If you want to to do this "properly", see http://ham-radio.com/k6sti/wifiyagi.htm When messing with antennas, things like distance needs to be thoroughly calculated. Foil can help in many ways, but it can also make things worse—antenna calculations are tricky.

> antenna calculations are tricky.

Especially at high frequencies. One of the first things I did when I got access to a computer as a kid was to write an antenna calculation program for Yagi antennae.

Impressive gain by the way, a factor of 8 (almost 9 dB) from that super simple mod.

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

#83

Post by jacquesm »

oleh wrote: post #30

Do not tilt the antenna though. Maximum emission of an dipole is perpendicular to its axis.

On occasion, going against the grain (in case of interference from another transmitter) can help if you can polarize the signal somehow.

https://en.wikipedia.org/wiki/Dipole_antenna

Of course you'd have to do the same thing at the receiver.

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

#84

Post by jacquesm »

agoodthrowaway wrote: post #69

Slight nit there's no amplification here just focusing to make the field more directional.

Gain is effectively the same as amplification, any kind of gain achieved in a passive manner indicates some kind of directional compromise.

It also should work equally well when receiving and transmitting, whereas an amplifier would work for only one direction (so you'd need two, one to output more power, another to amplify the received signal).

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

#85

Post by jacquesm »

gerdesj wrote: post #78
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.

Could you tell me where the /4 comes from, please?

Quarter wavelength. Waves will flow around something smaller than 1/4 of their wavelength almost without interruption.

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

#86

Post by throwaway613834 »

mrtksn wrote: post #37

It can work surprisingly well, I made a "dish" with an aluminum foil that was able to connect to a Romanian Wi-Fi hotspot from Bulgaria, according to Google Maps it should be something like 20KM distance. I should note that I had direct view of the town as I had significantly higher altitude. The hotspot was some kind of public service provided by the Romanian town as it's name suggested. The ip WhoIs also confirmed…

This seems great for sending but how does it work for receiving? Or did you somehow do this on both ends?

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

#87

Post by j1elo »

sp332 wrote: post #27
dukes_haven wrote: post #16

Earlier quoted context omitted.

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".

Wow. I'm one of today's lucky 10,000. Thanks!

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

#88

Post by gerdesj »

jacquesm wrote: post #85
gerdesj wrote: post #78

Earlier quoted context omitted.

Could you tell me where the /4 comes from, please?

Quarter wavelength. Waves will flow around something smaller than 1/4 of their wavelength almost without interruption.

Thanks. Could you point me in the direction of some reading material?

That has the look of a rule of thumb, which as a civil engineer that ended up in IT, sounds a bit familiar.

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

#89

Post by logicallee »

ars wrote: post #71
logicallee wrote: post #67

theoretically, are there any regulatory issues on a piece of aluminum sold (and marketed) for this purpose? if not, why aren't there cheap and effective such designs on alibaba - why have to DIY?

No regulatory issues. The aluminum acts to increase the antenna gain (i.e. concentrate the signal in a particular direction). The total power does not increase instead you take some from one place and add it to another. There are tons of products for sale. You can get a replacement antenna that is a directional dish for example, instead of the typical omnidirectional dipole (stick).

This was interesting, thank you. Given that we're literally talking about a piece of aluminum foil, I'm surprised this isn't more common.

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

#90

Post by vvanders »

gerdesj wrote: post #88
jacquesm wrote: post #85

Earlier quoted context omitted.

Quarter wavelength. Waves will flow around something smaller than 1/4 of their wavelength almost without interruption.

Thanks. Could you point me in the direction of some reading material? That has the look of a rule of thumb, which as a civil engineer that ended up in IT, sounds a bit familiar.

I've heard good stuff about the ARRL antenna book, although it's pretty large and spendy.
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