See also: http://mentalfloss.com/article/515193/researchers-develop-ch... ("Researchers Develop a Cheap Way to Improve Wi-Fi Coverage With Aluminum Foil")
I amplified my home's Wi-Fi with aluminum foil
131–140 of 181 posts
Re: I amplified my home's Wi-Fi with aluminum foil
#132Earlier quoted context omitted.
> Light will come out parallel No it won't, it's diffraction-limited. The best you can theoretically do is an https://en.wikipedia.org/wiki/Airy_disk You cannot construct, with any arrangement of mirrors or lasers, a beam that does not diverge.
I was assuming geometric optics... because it was simple enough to get the point across. Which of course you knew, but took the liberty to 'correct' anyway. It's quite impressive how you can always count on HN pedants to deliberately go out of their way to technically-correct you while making sure to completely miss the actual point you're trying to make.
You're the one that started in by trying to wrongly "correct" the statement "every improvement in sending is completely equivalent in receiving for a system that uses the same antennas for both directions of communication" (which is actually correct).
The fact that you can't have perfectly collimated beams and must make do with antenna pattern "lobes" is actually important here.
Re: I amplified my home's Wi-Fi with aluminum foil
#133Earlier 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. Does this actually make sense to you? Gain is a factor; it needs to be multiplied by something. Here's the obvious thought-experiment: consider an (ideal) parab…
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 reduces the loss (due to distance, since everything else is assumed ideal as you already acknowledged) to ZERO. You literally cannot do better than reducing your loss to zero.
2. With the receiver at the focus and the sender farther away, the mirror DOES NOT even remotely reduce the loss due to the distance to zero. Loss is still ~1/r^2. Because the mirror only gets so much of the omnidirectional light. This should be very obvious.
I don't care how you slice and dice this, and I'm tired of arguing something this obvious, so I won't keep commenting. 1 is not equal to 1/r^2.
Re: I amplified my home's Wi-Fi with aluminum foil
#134Earlier 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…
Thanks for the reply. I'm on the move, in my phone, and has regretted on posting the comment as it is hard to elaborate further given the situation.
Re: I amplified my home's Wi-Fi with aluminum foil
#135Earlier quoted context omitted.
The trick here (in this Wi-Fi example) is that the end you control is the end with parabolic antenna - if you can make it to collect enough energy for RX from an omnidirectional source, you can also make it send enough energy towards that source for its antenna to pick it up. But you're right that "every improvement in sending is completely equivalent in receiving for a system that uses the same antennas for both dir…
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.
Re: I amplified my home's Wi-Fi with aluminum foil
#136Earlier 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…
> 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. Does this actually make sense to you? Gain is a factor; it needs to be multiplied by something. Here's the obvious thought-experiment: consider an (ideal) parab…
You are assuming the mirror is parabolic.
Re: I amplified my home's Wi-Fi with aluminum foil
#137Re: I amplified my home's Wi-Fi with aluminum foil
#138I 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, some devices can be extremely noisy. If you have a Chromecast or Google Home, for instance, turn Guest Mode off -- it creates a hidden network on the same channel as your AP.
My chromecasts have been acting up really badly recently, I've just gone and disabled guest mode on them all based on this information.
Re: I amplified my home's Wi-Fi with aluminum foil
#139If 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.
Does anyone know what program the author is using? It looks interesting.
Re: I amplified my home's Wi-Fi with aluminum foil
#140That reminds of an article written by Amit Agarwal in which advocated the use of aluminum foil to increase Wi-Fi signal. The more things change, the more they remain the same.