121–130 of 181 posts
For optimal results, place the reflector at distance d = c / 2f behind the antenna (half wavelength). Where c is the speed of light and f is the frequency of your wifi. For example, for 5 Ghertz signal, that will be 30mm.
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I've also achieved substantial improvement with simple parabolic shaped, ~40 cm wide aluminum foil constructions, but there always seemed a bit luck involved and it needed some tweaking. Not sure whether the foil mainly acted as shielding that reduces the noise floor from other directions. I've read in other forums that fiddling with aluminum foil is mostly luck because additional reflective surfaces also introduce i…
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.
How is the author drawing those diagrams? Can I map my room with the strength of wifi signals at different points?
I want to do these small hacks but also want to see the change validated in some way. Any pointers will be appreciated.
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Or if you get your ham license you have a limit of 1500W PEP[1], just plug your callsign into the router ID and away you go. However that means you're also subject to no encryption or business related traffic. [1] http://www.qsl.net/kb9mwr/projects/wireless/allocations.html
>However that means you're also subject to no encryption or business related traffic. how does that work? isn't all wifi traffic encrypted by something between devices and AP? (I skimmed your link and did a find for encry on it but saw nothing.)
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> 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…
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…
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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…
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.
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This seems great for sending but how does it work for receiving? Or did you somehow do this on both ends?
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…
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 transmitting system, launching electromagnetic waves outward. These two cases are equivalent because of time reversibility: the solutions of Maxwell's equations are valid when time is reversed."
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> 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…
> 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.