aerials, Square(ials) etc

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Leonard Payne

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Mar 30, 2017, 8:58:11 AM3/30/17
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Hi guys

In my other thread regarding GL-AR150s and working with them, I raised the question of long distance wifi working.

I had a very fruitful conversation with Anish Mangal regarding his experiences with either Cantennas or Cantenna/Satellite Dish Combos, both of which have proved to give some good distances.

There are plenty of instructions online regarding the building of a cantenna and in the fitting to an old satellite dish, you simply replace the LNR, which is the bit pointing to the centre of the sat dish -- replace it with the cantenna.

Question
Now I know full well that if I take any tools to an old can, I am likely to lose my hand :-(

I've bought 2 of these little units

http://www.ebay.co.uk/itm/like/2-4Ghz-14dbi-Antenna-Panel-WiFi-Wlan-Long-Range-Extender-Directional-Router-SMA/301109590854?hlpht=true&ops=true&viphx=1&_trksid=p5197.c100068.m2280&_trkparms=ao%3D1%26asc%3D20140211125758%26meid%3D4aed8e7aa50146e2ab3b8f1000daf197%26pid%3D100068%26clkid%3D3599631265393282273&_qi=RTM2108002

Flat 2.4 aerials --- at that price I couldn't resist --- Do you think they will give me some distance.



Question 2
Obviously if I do connect some units at one end and connect them to another couple at some distance, they still logically are the same 'network'. How would you consider the distant Lan as seperate apart from the 10.n.n.n
space? What does the Duo firmware do?

Best
Leonard


T Gillett

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Mar 30, 2017, 9:29:22 PM3/30/17
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Leonard

It's not hard to get 10dB gain from this kind of "patch" antenna in a practical application so they can be a useful addition for directional use.
The cheap units are sometimes of poor quality construction with lossy coax cable which can easily negate any gain from the antenna itself.

Extending the network with higher gain antennas does not change the LAN parameters.

The Duo firmware is designed to allow the use of a second radio, plugged in as a USB device. It supports common devices in both Atheros and Ralink chipsets. There is some information about it on the VT Wiki page here:

    http://wiki.villagetelco.org/Using_USB_WiFi_Devices_for_Dual_Radio

You can set it up so that the internal radio runs the AP and the external radio runs the mesh, or vice versa.

There are some interesting "antenna" devices (like the one in the link below) that have the radio circuitry mounted inside the antenna housing right next to the patch antenna. This means that there is no RF loss in a connecting coax cable. The device then connects to your PC (conventionally) or SECN-Duo device via a (longish) USB cable. This allows you to position the unit in a good location for signal.
It is a little bit of a gamble buying these units as you often don't know what chipset is used. But most of them use the common Ralink chipsets and work OK with the SECN-Duo firmware.

Regards
Terry

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Steve Song

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Apr 1, 2017, 11:43:29 AM4/1/17
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Hi Leonard,

Just a short note to say that there is a lot of "caveat emptor" with antennas that can be purchased on eBay.  Your mileage may vary wildly in terms of promised vs actual performance.  If you are interested in DIY antenna design, I recommend watching some of Andrew McNeil's youtube videos.  


He does a number of teardowns of the kind of inexpensive antennas you can find on eBay.  The results are informative.  :)

Cheers... Steve



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