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Good directional antenna for AWUS036NH?

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caissyd

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Post Thu Mar 28, 2013 8:59 am

Good directional antenna for AWUS036NH?

Hi everyone,

I am looking for a good directional antenna for my AWUS036NH wireless card.
I currently own this kit and I like it a lot: http://www.amazon.ca/gp/product/B0035BGNWU/ref=oh_details_o00_s00_i00?ie=UTF8&psc=1

But I now want to practice finding specific MAC addresses. For example, if someone is using my "very secure" WEP based access point and I want to find out where he physically is. Another example would be to find a rogue AP. So I figured out that a good directional antenna will greatly help me find those devices.

So, I did some research and found these directional antennas:
- 16 dBi Yagi antenna (http://www.aliexpress.com/item/NEW-16-dBi-16db-16dbi-2-4-GHz-2-4G-802-11b-g-Wifi-Yagi-Antenna/498207056.html) This is made to be permenantly mounted outside
- Yagi 12dBi Compact Directional Antenna (http://www.aliexpress.com/item/Yagi-12dBi-Compact-Directional-Antenna-For-WiFi-RP-SMA-Router-Switch/499155533.html)
- 2.4GHz 18dBi SMA High Gain Dish Directional Antenna for WiFi/Wireless Network (http://www.aliexpress.com/item/Free-shipping-2011-Latest-2-4GHz-18dBi-SMA-High-Gain-Dish-Directional-Antenna-for-WiFi-Wireless/373762221.html)
- WIFLY-CITY 2.4GHz 10dBi R-SMA Directional Antenna for WiFi/Wireless Network (http://www.aliexpress.com/item/WIFLY-CITY-2-4GHz-10dBi-R-SMA-Directional-Antenna-for-WiFi-Wireless-Network/339263021.html)

And there are way more out there!

So, do you guys have any suggestions for me?

Thanks in advance!
OSCP, GPEN, GWAPT, GSEC, CEH, CISSP
(aka H1t.M0nk3y)
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Matthias2012

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Post Fri Mar 29, 2013 12:00 pm

Re: Good directional antenna for AWUS036NH?

Hi,

maybe I can help you...
Working in an institute for research and development of antennas and all other em-stuff I will ask my colleges about your ideas... Give me a little time to find out who is the best I can talk to..
If you like to take a little look.. www.imst.com

Regards
Matthias Dörfer
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eCPPT - C|EH - MCITP
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caissyd

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Post Wed Apr 03, 2013 7:52 am

Re: Good directional antenna for AWUS036NH?

Great, thanks Matthias2012!
OSCP, GPEN, GWAPT, GSEC, CEH, CISSP
(aka H1t.M0nk3y)
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Matthias2012

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Post Thu Apr 04, 2013 12:09 pm

Re: Good directional antenna for AWUS036NH?

Hi,

I've asked my college and now I try to translate what he said to me. I remember you told me that the german language is not your favorite.. ;-)
The idea of a directional antenna is right but it is only just the first of three steps. If you buy an AP the build-in antenna is nearly omnidirectional, that means the electromagnetic output goes everywhere. If you are searching for an AP or a user that uses your AP remember he can be everwhere within the reach of the AP. In a few weeks we organize another recruiting day and give them a change to build a WLAN antenna by there own. My college gave me some papers about the last one and I find for you an similar in the net.
http://martybugs.net/wireless/biquad/
I`ll send you the two pdf, nevertheless they are in german look at the pictures. In wlanprojekt.pdf the first two pictures shown on page 7 you will see the result..
Just the picture below shows one of the steps next after you mount a directional antenna on a tripod.
Why? Open the other pdf and look on the outputcharacteristic of that antenna on page three.
What is the trick on it? So the trick is it is directional!
So your choice of http://www.aliexpress.com/item/Free-shi ... 62221.html will work fine for this purpose on an tripod. You can turn it with the tripod an in/decline by itself. The next step, I told you before, is to measure signal strenght and link quality each heading and inclination (like they did with D-LinkAirPlus shown in the picture below the result pictures last pdf) and then you have to move your point of view with the tripod to do a crossbear!
In the second pdf you can also see a solution with a satellite reflector and something that looks like a "pringle role"
I hope I could help you...

Regards

P.S. how can I send attachment PDF larger than 128k?
Matthias Dörfer
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eCPPT - C|EH - MCITP
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Mightygreen

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Post Fri Aug 16, 2013 8:12 am

Re: Good directional antenna for AWUS036NH?

Finally something I may be useful in...

Anyways I'm not sure of your experience with antennas, RF theory, or the like so forgive me if I say things you already know.

First off be wary of dBi - decibles isometric is there to make antennas look better than they are...I believe it's 2.5 dBm higher than the actual gain of the antenna (i.e. a 9 dBi gain antenna is actually 6.5 dBm) dBm is a much more reliable figure (stands for decibles milliwatt) and there are many calculations you can do with it (complicated and simplified) to determine distance, signal strength, power output, etc.

Secondly Yagis are great directional antennas, along with them are LPAs (Log Periodic Antenna) and Bi-Quads. Any higher gain antennas would probably be parabolic dishes which would be your best bet, but generally very expensive. Also parabolics tend to be more secure due to small side lobes in their RF propagation and a thin beam-width.

Lastly if you are going with anything but a parabolic (the calculations for correct measurements and the different styles tend to get complicated) I would recommend to just make it yourself, most pre-fabricated antennas are over-priced especially when with some cardboard and copper tape you can make a very good yagi (I believe one of the ones I have made in the past was 14 dBm gain over the quadband monopole we were using) for a couple dollars. Yagi calculations can get complicated but I have a calculator in excel that does everything but make it for you (can supply if needed once I figure out how to on the forum). LPAs get complicated and are more for directionality on a wide range of frequencies. Bi-quads are also very easy, simply each side is 1/4 lamda (wavelength) with a 1/8 lamda distance between the antenna and a reflector (small sheet of metal larger than the antenna) and then you connect the positive and negative of the coax to the antenna (in the middle part of the 'figure 8', each to a side, top and bottom respectfully), I have noticed that people tend to use bi-quads due to their simplicity over yagis for wifi, also they are a little more compact.

Sorry if this is not exactly what you were asking for (which may have just been advice on the antennas you scoped out) but I was happy that I found a thread I knew something about (being near-total n00b with Linux and programming, currently learning through research, luckily I have a lot of time to read at the moment). If this is not what you were asking for I hope that at least I shared some knowledge you or others may not have known that may save someone some money.

If you have any questions PM me or post here, may take me a few days to respond, so if there is a delay please be patient.

;D

EDIT: I kind of took it as implied, but all these antennas are great for DF.

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