Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

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

jiffchat.com

Post reply on HN
Print view View original

141–150 of 181 posts

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

#141

Post by aylons »

throwaway613834 wrote: post #135
aylons wrote: post #126

Earlier quoted context omitted.

No, as long as antennas and signal power is concerned, I stand by what I said: every improvement in transmission power has a equivalent improvement in receiving power. If you have a more specific doubt, please, feel free to ask.

> If you have a more specific doubt, please, feel free to ask. Unless by "feel free to ask" you mean "I don't plan to answer", this doesn't really seem like a sincere suggestion. I already did this and you didn't answer.

I'm still on the move, but I'll answer eventually. Your previous post did not contain any questions.

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

#142

Post by lpmay »

For the antenna case (and I believe for the optics case too, but I'm not an optics guy) the beam disperses as 1/r^2 in both cases.

In transmit , the reflector provides focusing, which puts more power in less of the volume. In receive, the increased aperture allows the antenna to capture a greater area of the incoming wave giving more receive power. The effects are equal and usually just thought of as"gain" which is reciprocal for transmit and receive.

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

#144

Post by stordoff »

godelmachine wrote: post #4

I am using my neighbors WiFi, which I can only catch in my balcony. He stays above me, but diagonally opposite, so the source is quite away. Any way I can amplify the WiFi strength? So I need the source to be around in order to amplify?

The repeater suggestion is exactly what I did at university. There was a network I could _just_ pick up most of the time on my laptop that I wanted to use (run by the central university rather than my college so it had fewer usage limits). Putting a DD-WRT router by my window which connected to it as a client, then shared the connection over Ethernet, got me a rock solid connection.

It also lets you put your devices on their own subnet/NAT, which is nice from a security perspective (I've do this at home quite a lot - re-purposed router connects the main network on 2.4GHz and treats it as a WAN, then provides its own connections on 5GHz).

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

#145

Post by dpark »

throwaway613834 wrote: post #133
friendzis wrote: post #118

Earlier quoted context omitted.

Yes, it does make sense to me. I think conclusions drawn from this thought experiment are not entirely correct. Under your experiment when sending you spatially create a beam - there is this beam as wide as parabolic dish and no light anywhere else. With zero interference (using the word quite freely) this beam "will be just as strong no matter how far away the receiver is". With roles reversed, you do not necessaril…

> With roles reversed, you do not necessarily get directional transmitter. I don't get why you put "necessarily". You do not, period. > [...snip...] but the claim was "every improvement in sending is completely equivalent in receiving for a system that uses the same antennas for both directions", key word improvement . Yes, the claim is wrong : 1. With the sender at the focus and the receiver farther away, the mirror…

> I'm tired of arguing something this obvious

You're arguing a scenario that is impossible both practically and theoretically and then calling others pedants for pointing out the fundamental flaws in your thought experiment. You're literally arguing against the textbook and then asserting that your thought experiment is close enough to make your point. It might be time for you to stop assuming that everyone else is an idiot and entertain the notion that you might actually be wrong.

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

#146

Post by stordoff »

pishpash wrote: post #50
Aloha wrote: post #49

I don't think this is working the way he thinks it does. What he's likely do is shielding the wifi receiver from co-channel interference, which is likely reducing the noise floor at the AP - which is giving him effectively more range, because now the AP can hear stations that are further away with greater ease. I don't think this is giving expanded tx coverage lobes as his diagram indicates, its likely a function of…

Yeah, something so imprecise isn't likely to work as he thinks. Proper shielding can do a lot more. If you made your house/apartment a Faraday cage and eliminated neighbors' AP's that would already solve most problems.

I can see this working well, unless LoS goes through one of those walls. There's a metal mesh in most of the walls of my house (putting two routers directly opposite each other on either side of an internal wall will cut the signal strength to about 60%), and trying to get a reliable signal because of the shape of the house (roughly L-shaped) was a nightmare (line of sight was through two external walls).

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

#147

Post by kijin »

westmeal wrote: post #123
kijin wrote: post #115

Earlier quoted context omitted.

A wok (Chinese stir-fry pan) works surprisingly well for this purpose. It's roughly parabolic, and has a smooth surface that helps you avoid irregularities in the shape of your foil. It gets even better if you drill a hole in the center and stick an antenna vertically in there. Now you've got a wi-fi antenna with all the advantages of a satellite dish! The Chinese call it wok-fi.

Huh... no kidding. I'm going to have to try that out some day. How was the signal like on the wok with the antenna through the center?

I haven't personally tried sticking an antenna through a wok (just putting one behind the router was enough for my purpose), but rumors say that you can achieve a range of several miles if you do it right.

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

#148

Post by [deleted] »

pjc50 wrote: post #128
aylons wrote: post #94

Earlier quoted context omitted.

It's not needed to do it in both ends. Naturally, improving both antennas is better than doing in only one, but every improvement in sending is completely equivalent in receiving for a system that uses the same antennas for both directions of communication. So, if a new antenna in client side improves signal reception by 3dB, it also improves transmitted power by 3dB. If you used the same antenna on the other side, t…

I don't know why people are arguing so much with this when it's straight out of textbook antenna theory. Evidently it's very HN to work things out inaccurately from first principles. Edit: http://www.cv.nrao.edu/course/astr534/AntennaTheory.html "An antenna can be treated either as a receiving device, gathering the incoming radiation field and conducting electrical signals to the output terminals, or as a transmittin…

[deleted]

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

#150

Post by madengr »

Just keep in mind you need some antenna diversity for the MIMO to work. Adding the foil increases the directivity, which you don’t want for MIMO. Though it improves fringe reception, it may reduce the data rate for devices that already have sufficient SNR.
Post reply on HN