The Hackers Lab - WiFi Dish

diy
wifi

([email protected] [email protected]) #1

Holy cow! A Satellite dish?!

Yup…You read that right!

Today, I’ll be doing a write up on creating your very own WiFi range extender using an old satellite dish!


Resources:

1. Build pictures
2. Results pictures


The finished product


How does it work?

Now, we’re going to try and explain this without the fancy mathematical equations that goes into the positioning and curvature of the dish.

At its base, a satellite dish is simply a parabolic RF (radio frequency) reflector. WiFi is a type of radio wave, similar to those being transmitted by a satellite that’s orbiting the earth.

The dish is comprised of three main things:

  1. A parabolic surface
  2. A feed horn
  3. An arm to hold the feed horn away from the surface of the dish

In traditional satellite dishes, the feed horn is called a Low Noise Blockdown converter. Or LNB for short. It amplifies the radio signal that bounces off of the dish and filters out signals that don’t have a television channel on them.

The way the parabola is shaped makes the dish point upwards even if it seems as though the dish is pointing forwards.


Cool, but can I see some visual Aids?

Absolutely!

Here we can tell that the parabolic dish doesn’t actually receive the best signal from having its center aimed directly at the source.

In order to understand this concept, think of a ball and a cone shaped bowl. If you throw the ball directly into the center of the bowl, all it’s going to do is bounce right back at you because of the flat surface in the bottom. However, if you throw the ball at the inside angle of the bowl just right, the ball is going to hit the side, then the middle, then it will come out of the bowl on a downward angle. Just like what we see with a satellite dish.


So…When are we going to build this?

Right now!

1.) To begin with, you’re going to want to acquire an old satellite dish. Usually you can get these from your local junkyard or on-line, but I got mine from my grandmother who had just gotten a new dish installed.

2.) There will be a set of coax cables inside of the arm of the dish. This is what was used to connect the LNB to the house. You’ll need to remove these and you can either toss them out or reuse them for another project.

Coax cables inside the arm

http://i.imgur.com/ELwuiYPg.jpg

3.) The next step will be to clean the dish in order to remove the dust and grime from weathering. You could use a Brillo pad to get everything off, but I didn’t bother since it won’t end up drastically changing the signal.

Cleaning the dish

http://i.imgur.com/5ItAlx5.jpg

4.) Afterwards, you’ll need to make a base for it. Feel free to get creative since it will most likely be a cylindrical mounting pole without any kind of bottom bracket on it. If I had the time or materials, I would have welded on a steel base. Make sure you have legs that extend out front. Otherwise your dish WILL fall forward.

5.) The next and final step is mounting your favorite WiFi card! I used an Alfa AWUS036NH external WiFi adapter with a parabolic antenna.
Since my card came with a sheath and a clip to go on the sheath, I simply clipped the card onto the arm and ran the cables through!

Clipped and ready to go!

http://i.imgur.com/0gsLBL9g.jpg


Results!!

Don’t worry! I didn’t forget.

I personally believe the results I received were exceptional, especially for a mis-configured dish. I went from 9 access points to a whopping 15! That’s 6 more access points than without the dish.

[details=Without the dish]http://i.imgur.com/572Yp8qg.jpg
http://i.imgur.com/QZAlVYqg.jpg[/details]

[details=With the dish]http://i.imgur.com/IbFVRwgg.jpg


http://i.imgur.com/WBLD20Og.jpg[/details]


Things to think on:

  1. Something that popped in my head while I was writing this article was wardriving. Imagine mounting this atop a van or something!

  2. What other things do you think you could use this for? Remember, all it really does is catch and reflect RF waves!

  3. Do you have any DIY WiFi or RF equipment? If so, what?


([email protected] [email protected]) #2

I will update the build pics soon. I needed to change around the order and text of some of the images.

EDIT: Build pictures are updated!! Feel free to check em out!


(Command-Line Ninja) #3

Sweeeet. I need to do this. I have the exact same alfa card but without the parabolic antenna, I have the omnidirectional one.

This would be cool if you were in a hotel, or in a place high up with no wifi (especially in the city). I often use to accompany this kind of mesh-network-esq wifi sharing with a cool script called create_ap in the AUR. It allows you create an access point super easily without messing with DHCP servers and airbase.

My only issue with using the alfa card would be weather proofing, mounting this on your porch outside for a period of time would likely lead to your card getting fried by the elements. Perhaps we could make some sort of enclosure? Or… Just get a waterproof parabolic antenna and connect it to the card :stuck_out_tongue:

Does anybody have any recommendations for network cards + antennas other than the Alfa?


([email protected] [email protected]) #4

Ah, I see where you’re coming from. A workaround could be to create your own antenna, and then feed the wire from your antenna down into your window leading into your wifi card that’s inside of your house. You would need to bend the wire into a U shape so that runoff water doesn’t reach the card.

Or the alternative would be to drill a hole in your siding/roof and feed the wire down through there :laughing:. You’d have to make some sort of a watertight seal though.

EDIT: The omnidirectional antenna ought to work, but maybe not as good as the parabolic one. I’m not 100% for sure because I’ve not yet tried the omnidirectional antenna.


(Not a N00b, but still learning) #5

What about the latency/throughput of those networks far away? Could you post some tests? :stuck_out_tongue:


(Command-Line Ninja) #6

I think if I put it inside a tin can it would make it parabolic.


([email protected] [email protected]) #7

I’ll leave that bit up to the reader! I’m not just gonna hand over everything. :smile:

@pry0cc Yea. I was actually thinking about exchanging the default parabolic antenna with a cantenna. I feel like it’d do better, but I’ll save that project for another day!


#8

Good article mate. This one feels less rushed compared to the arduino one but instead it reads more like a well thought of concept.
Keep it up.


([email protected] [email protected]) #9

Ay, I couldn’t really think of much for the arduino unfortunately. All the info was already out there within a less than 5 second google search lmao. I just felt like I needed to do it for the sake of completion. Thank you!


(system) #10

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