Extend omni-antenna campus wifi 150m with DIY yagi

[progrange]

Hi there,
I'm just about to move in 150m(~500ft) from the institute where I study, and I would love to get some input on whether my plan to extend the university network to my house will work. Please bear in mind that I'm one of those cheap-ass students that try to do this with as much DIY as possible, both for the sport of it and economy.

The uni network has a bunch of high-end routers, each with 4 'ducky' antennas scattered around the building. I have access to turn these antennas to align them with mine or vice versa. Some of them are close to the windows towards my house. There is clear line-of-sight, but some small trees as seen in this picture (taken from the campus building)

My initial plan was:
- make a ~15dbi yagi antenna like the one showed here at ab9il.net . (I have access to a workshop with more precise tools)
- Hang this antenna in the window or outside [EDIT: of my house] pointing towards campus
- align it with the antennas on campus
- connect antenna to a wireless router #1
- connect router #1 to another router #2 through ethernet
- router #2 sets up the in-house wireless network to which we connect our computers

Unfortunately I don't know yet what type of routers will be used as I haven't sourced them yet, and I don't know the model used on campus, but I can find out later.

So if any of you have ideas on whether this would work or not, I'd really appreciate it! I know it's not possible to give definite answers with such a loose plan and with many variables, but at least to know whether you think it will be enough or if I have to set up for instance a point-to-point bridge system. Seems you guys have tons on knowledge, so it's good to get input from others before I begin making stuff

Thanks!

 

[COLGeek]

Do you have permission to re-orient the school's antennas? If not, don't even chance it. Also, when you adjust equipment, as suggested, you may impact other students. You are better off, for the good of all, leaving this stuff alone.

If you have clear line of site, you may be able to access the network with your own directional antenna without messing with the school's equipment. As long as you are an authorized user, and can get a clear signal, you should be fine.

 

[Pooneil]

It's a plausible design if you can use an N150 router with one external antenna and can keep the antenna wire very, very short.

I understand the need for students to be economical and also to want to hack things. But an alternative if the build your own doesn't work would be to use a directional bridge from Engenius. You can usually buy from Amazon with a decent return policy in case it doesn't work. Just be ready for the installation when you order so you don't run out of time.

If you build your own, please post back and let us know how it worked.

 

[progrange]

Thank you for your answers, both of you!

COLGeek, your concern for impacting the other students is a good one, but there is really plenty of routers and coverage, as much so that the networking guys don't even bother to orient the antennas. And yes, the idea with the directional antenna is to install the stuff in my own house so that I don't mess too much with the institute's stuff.

Pooneil, thank you for the bridge idea, I will definitely consider it. And yes, that's the good thing about having a separate router for just relaying the signal to ethernet; it can be attached centimetres from the antenna
I see some routers have two or three antennas. Would it work to use one of those and connect one directional antenna and two omnis and let it just forward wireless to wireless, or would it impede performance?

I'll post the result when I get it done!

 

[Pooneil]

I see some routers have two or three antennas. Would it work to use one of those and connect one directional antenna and two omnis and let it just forward wireless to wireless, or would it impede performance?

My understanding is that multi antenna routers need use all of them to operate properly. For instance, one is for sending and another for receiving. So attaching a single directional antenna will not necessarily work for for both send and receive. There may be some routers that would work, but one would have to know which specific models will work, which I do not. Thus the KISS principle recommendation of the single antenna 150N system as the most likely to work. If you want to experiment with a two or more antenna model, well that's what hacking is all about. But prove the antenna first with a simple system.

 

[progrange]

So I've finally got hold of a N300 TP-Link router for free (TL-WR841ND), which I'll try without any mods first, but a new question struck me:

I've just assumed that in order to get the highest possible speed and capacity out of this setup I should use it in client bridge mode and connect it by ethernet to another wifi router which sets up the in-house network. I have a feeling that having a dedicated wireless connection working only between the two houses is beneficial. Is this correct, or will I get the same result by just using it in repeater bridge mode? I suspect more talk between devices may slow things down as well?