Range Increase with Cantenna???

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MacTavish
DD-WRT Novice


Joined: 05 Feb 2010
Posts: 2

PostPosted: Fri Feb 05, 2010 20:34    Post subject: Range Increase with Cantenna??? Reply with quote
Hey all,

I will be very upfront with everyone here by being the first to say that I have very limited technical skills when it comes to wireless networking. So if you throw some technical jargon into this thread please place a corresponding link, thanks. However, I am not a total noob. I did successfully upgrade my router with the DD-WRT firmware on the first try without bricking it. Alright, now that we're all clear, here's my project:

I currently have no internet access where I live, so I am attempting to connect to the public library's unsecured wireless network. I live only 1 block away from the library and I have a clear line of sight to it from my window. Unfortunately, I cannot see the network from my house. I think I am just outside of its range. So, my project is to create an antenna of sorts (as cheap as possible) to increase my range.

Does anyone have experience creating and hooking up a homemade antenna to their router to receive free wireless internet? I am considering either the cantenna method (which I am still unsure how to do) or using an old direct tv dish in my backyard to fashion some sort of uber antenna. If anyone has any advice, links, etc that would help me in this project I would be much obliged. I currently have a WRT54GS v7.50.0 Wireless Router that was successfully flashed and upgraded to the latest version of DD-WRT.

Thanks!
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Nekota
DD-WRT Novice


Joined: 30 Mar 2008
Posts: 14

PostPosted: Fri Feb 12, 2010 8:38    Post subject: Range Extenders Reply with quote
A bowtie antenna is much better than the cantenna style, is not so hard to aim and if you don't want to make one you can find them already made on ebay. With the dish you can use the bowtie to 'illuminate' the dish and get even more range but you have to have a better aim. It's important to keep the cable short and using a larger diameter coax reduces the signal loss. The largest part of the expense is the rf connector to attach to the router - the rest of the antenna can be constructed from a 4x6 single sided copper clad pc board (radio shack), I used 18" of RG58 and a brass tube insert for the antenna standoff from the pc board. Probably about $15 worth of parts with almost half in the connector.
MacTavish
DD-WRT Novice


Joined: 05 Feb 2010
Posts: 2

PostPosted: Fri Feb 12, 2010 18:45    Post subject: Reply with quote
Ok ok, good advice. Thanks. I plan on making the bowtie dish antenna setup instead of the more primitive cantenna. However, I'm still foggy on the exact materials and connectors:

-12 gauge copper wire? (to create bowtie)
-thin copper sheet or copper plated circuit board
- A female N-connector (to mount in the antenna)
- RP-TNC Pigtail????? (N-connector to Linksys WRT54GS removable antenna slot)
- What else?

Will this connection work??? : modified bowtie dish antenna > wireless Linksys router WRT54GS > My computer via ethernet cable.

And if that will work, what settings do I need to put my router in? Client Bridged mode? Repeater? Repeater bridge?

Any comments welcome! Thanks!
TinCanWaveguide
DD-WRT User


Joined: 05 May 2008
Posts: 62
Location: Near Area 51, Nevada

PostPosted: Tue Apr 13, 2010 14:17    Post subject: I love cantennas Reply with quote
Or tin can waveguides, I have built dozens of them. The dimentions of these are critical to their effectiveness, the diameter should be between 80 and 90mm, I prefer the large us sauce cans, that are 3.25 inches (same as a tuna can), and the taller the better. Those work out to about 83mm, they are the only cans that are anywhere close, but they are perfect. The element needs to have 30mm exposed inside, and last, and most critical, is that the element needs to be 2.5 inches exactly, from the back or bottom of the can.
http://www.educypedia.be/electronics/antennacantenna.htm
http://kioan.users.uth.gr/wireless/cantenna/
http://www.turnpoint.net/wireless/cantennahowto.html
http://www.saunalahti.fi/elepal/antenna2.html
http://www.saunalahti.fi/elepal/antenna2calc.php
Those links should get you going on the right track, but the dimentions I gave you are as close as you will ever get to the perfect cantenna. Use as little coax as possible, usb adaptors can be directly attached, and can the bullet2hp, mine loves the cantenna. Mine gets 3x the signal of even my best vertical antenna, and mounting it appropriately on an old sattelite dish got 3x more than that, connecting to a hotspot over a mile away, once.

_________________
Perfect Cantenna: Use the big spagetti sauce cans, 3-1/4" diameter. Make the element 31mm long, and place the element exactly 2-1/2" from the bottom of the can. The dimentions are critical, and these are perfect.
Buns
DD-WRT Novice


Joined: 11 Apr 2010
Posts: 5

PostPosted: Sat Apr 17, 2010 10:16    Post subject: Reply with quote
My thoughts MacTavish`

Can you see the radio? If so, go here;
Code:
http://www.terabeam.com/support/calculations/fresnel-zone.php


Things too know;
distance, radio type ~Brand-Model, height of radio, down tilt if any, inside/outside, etc.

If the Library uses 2.4ghz 802.11g/ODFM or b.

You will like the Ubiquiti NS2 Loco, easy setup, cat5e, signal strenght indicator build in, etc.

I know I left a lot of unanswered questions, the Fresnel Zone cal will give you an idea of what you need too do.
canclan
DD-WRT Novice


Joined: 13 May 2010
Posts: 25

PostPosted: Thu May 27, 2010 1:34    Post subject: Reply with quote
I made two of these:
http://www.freeantennas.com/projects/template/

which were easy and fast and bumped up my signal between 10 and 20db, but that was *not* over a block.
Also, you could try:

http://binarywolf.com/249/diy-parabolic-reflector.htm
http://24.106.181.178/geocorona/index.html

They all attach directly to a router antenna, which may or may not be what you are looking for (especially if you do not have a convenient line of site to the library. You could setup the router as a wireless bridge (I think it is called) perhaps (?)

As far as the dish network setup goes, I think the LNB is setup for a specific range of GHz frequencies and filter out others. I am not sure how sensitive the LNB would be in the router's range. The dish size would be awesome for signal collection though!

Anyway, my two cents.
TinCanWaveguide
DD-WRT User


Joined: 05 May 2008
Posts: 62
Location: Near Area 51, Nevada

PostPosted: Mon Jun 14, 2010 14:45    Post subject: Reply with quote
The dish isn't band specific, it's like a magnifying glass, only reflective: The curve of the parobela focuses all the energy that reflects off of it's surface to concentrate at a single focal point. This is where the collector head of the original feed is. Mount the cantenna at the same angle, with the opening at the exact same place as the original head was, point the whole dish at the signal, should 3x the signal.

Attaching directly to the radio eliminates the loss inheirant to the coax, which increases with frequency, it gets bad at 2.4ghz, so less coax or coax with less loss it a plus.

_________________
Perfect Cantenna: Use the big spagetti sauce cans, 3-1/4" diameter. Make the element 31mm long, and place the element exactly 2-1/2" from the bottom of the can. The dimentions are critical, and these are perfect.
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