making 2.4ghz pringles cantenna.

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thecrazzyman

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Hi. new to this forum but have been reading everything i can get my dirty little paws on for the last couple days. I am currently building a cantenna. just like this
http://www.turnpoint.net/wireless/cantennahowto.html
my dimensions are a bit different but im trying to figure out how they got to the length of the probe to be 1.21 inches long. where are the formulas also does it make a difference what the probe is made of? what if it was square rod? or oval? what about a grid made from smaller copper wire? is there any advantages? im just trying to always improve and find different ways to get the same thing or better.


Thank You
 

mancow

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I made one from two bean cans. I used a panel mount N connector with a piece of wire stuck in the center connection that was about that same length. It worked fairly well.

The best antenna I have ever used for 2.4 Ghz is a helical. I found a program to design them when I was looking to make one for 1.5 mhz for Inmarsat reception. I just entered the figures for 2.4 and tried one for that band.

I went to Home Depot and got one of those clear tubes they sell in the lighting section that is used to slip over flourescent light tubes for shatter security. I had some 1/4 inch or smaller copper tape used for stained glass hobby stuff. I found it at the local stained glass and modern art stop by and spew your liberal drivel coffee shop.

Anyway... I just wrapped it around the tube at the proper spacing. I used a compact disc as the reflector and some aluminum duct tape to hold it on. I put a panel mount BNC in the disc and soldered it to the helical copper end where it met the bottom.

I can pull in stuff with that antenna that I couldn't get with an expensive hi gain mag mount made for wardriving. The best part is that it's circularly polarized so it doesn't matter what the orientation of the signal is.

I think I left it at work since we use it mainly for 2.4 ghz camera work but when I run across it I will post a picture.

I forgot to ad this too.

Check out the Slinky JR toys. They are the mini version of the regular slinky. Why they exist I don't know but they happen to be almost the exact diameter for 2.4 ghz. I made all my 1.5 ghz helicals from regular slinkys and they work great. The best part is the slinky is easy to work with, maintains even spacing, and is very strong. The JR model is even easier to work with due to its size. I plan on making a better 2.4 ghz model from one when I'm not lazy.


Here's an example of the 1.5 Ghz Slinky helical Version 2.0. It is made from wooden dowels. They supports are dowels that were placed into holes drilled into the center dowel shaft with a drill press. This antenna performs much better than the one with the aluminum center L boom. I assume it's due to the interaction the metal boom had with the coil.

IMAG0068.jpg


IMAG0069.jpg
 
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thecrazzyman

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wow good idea.
i plan on mounting this to a big seatel tracking tv dish i got that is going to be controlled by the computer. the plan is to have the dish scan one line at a time and have the computer record the signal strength that is comming back. so one pass from bottem to top then one step right then down would spit out numbers like at the bottem all of thies would be taken from what ever software shows me a signal strengh meter. in the end i want it to show up like a picture and assign numbers a color. so 0 is black and 50 is red. then make a radio map of my area. its a bit of a project to take on and im quite lost at the moment but it will be so fun.
76
46
45
56
64
10
87
56
23
00
sorry for spellin and that stuff. i just am busy and too many things to do. i do try some.
 

mancow

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Yea, I don't know how the cantenna would compare with the helical as far as directional selectivity goes but I think the helical would probably be quite a bit tighter. I can tell you that with satcom stuff it's within a few degrees that the signal rapidly fades to nothing at all. I would think with 2.4 it would be that much tighter. It might be something to consider if you are looking to get as accurate readings as possible when it comes to direction of signal.

Or, you might just spring for a 2.4 yagi. I would hate to see your research go to heck due to an antenna that isn't directional enough.
 

thecrazzyman

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its always fun to learn new things so looking up yagi's could be fun. the only reason i used the cantenna is its 7.7 inches long so its not sitcking up the parablic dish that much. so its not so huge. the dish is 32 inches so its already big.
 
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