That being said, it's a clever bit of engineering.
I was going to make it the centerpiece of the living room but my girlfriend vetoed that.
As with the original link, the antenna is directional (and since it's a reflector, probably even more directional), so you lose out on flexibility. It'll be quite good if you don't plan on moving the other point, though.
But if the clients are all near each other, you have some money to spend (~$100), and don't mind being stuck with one band (2.4 GHz or 5 GHz), I'd recommend one of these:
https://routerboard.com/RBSXTG-2HnD
https://routerboard.com/RBSXTG-5HPnD-SAr2
https://routerboard.com/RBSXTG-5HPacD-SA
They're really meant for outdoor installations but they work well for indoors with a cluster of clients far from the AP.
[0] https://en.wikipedia.org/wiki/Equivalent_isotropically_radia...
Basically APs on 2.4 GHz are only allowed 36 dBm (4 W) EIRP, no matter what antenna shape. This is usually not a problem though, since stations tend to have weaker transmitters anyway, but will still benefit from the AP's enhanced antenna gain.
http://w5vwp.com/wifihams.shtml
(Of course then you are subject to all the Part 97 restrictions like no encryption, no commercial use, etc)
1: http://hraunfoss.fcc.gov/edocs_public/attachmatch/DA-00-2225...
That being said if you're using this in your home/office on a legal channel it would be really difficult to even tell from outside you were using it and almost certainly not worth the FCCs time to even try to watch for it. It's not that much extra gain over the stock antenna.
The antenna is not supposed to be replaceable, hence the reverse SMA connector on most modems.
Modifying the antenna in any way invalidates the type approval.
Because it's illegal, is why.
You can buy directional APs if you want, but they're usually used for outdoor point-to-point links, or as sector antennas. e.g. I just installed one of these today: https://routerboard.com/RBSXTG-2HnD in a place that needed a signal far from where the AP was. Usually patch antennas (like this product) are preferred over Yagis for microwave links due to their smaller footprint, and capability of dual polarization in a single package.
Better is if your indoor AP can transceive in more of a "pancake" shape, like this: https://routerboard.com/RBOmniTikU-5HnD Note that's almost the same gain as this home-grown Yagi (7.5 dBi vs. 8.5 dBi) but with a more useful directionality.
It's not all that useful indoors though as 2.4 and 5GHz signals bounce off of walls really well so you lose much the directionality at the very first wall it hits.
1: Actually there is a total ERP requirement, but most routers with external antennas are already close to that requirement, so more than about 3dB gain will often put you over.
The trade-off is worse performance perpendicular to the extra elements.
When you pull on a chain or a rope, it doesn't matter if the other side is "receiving" the pull, or "sending" it. The two sides are physically coupled.
Similarly, antennas are physically coupled to each other. Increase the gain on one side, the other side still benefits. You're physically connecting a "rope" of electrons over the air.
Pragmatically, this means it's only really an option on routers with external whip antennas. Lots of routers have internal antennas, at which point you're going to have problems attaching the thing. Also, if the internal antennas aren't dipoles, it's not an option at all without significant redesign.
There's tons of free and/or open-source software (of varying quality) for modeling antennas and such as well.
[0]: http://www.arrl.org/antennas
[1]: https://www.arrl.org/shop/ARRL-Antenna-Book-23rd-Softcover-E...
In my university we had several courses on "analog electronics" which covered topics like free space path loss and RF concepts (e.g. bandpass filters).
2. Use Google or another search engine (DDG) to find the book in PDF or EPUB version.
3. Enjoy reading the book without forking over hundreds of dollars to a greedy publisher.
-beamforming
-split 2.4ghz/5ghz/5ghz-wave2 antennas
if your router is using those three antennas for beamforming, you might trigger some strange behavior if you yagi a single one of them. if run into issues and can turn beamforming off, you should be able to yagi a single one no problem.
if your router pumps each antenna into a separate radio, then you can reliably pump a single radio into that corner of your house w/ a yagi. however, you won't have seamless roaming between the 2.4ghz and 5ghz networks when you move into and out of that corner of your home.
i recommend getting a mesh network, they're the bees knees and are a huge step above the traditional access point + range extenders model
http://www.tomsguide.com/us/how-to-bluesniper-pt1,review-408...
