Wifi antenna, DIY or not.

[The Dong]

If anyone is vaguely interested.
Poking about in the wifi neighbourhood is a passing interest ;)

I've recently built about 5 different wifi antenna, from directional 
biquad and various antenna, to omni, twisty, bendy wire and coax 
monstrosities.

None of them have been particularly successful, even the bought ones 
were pretty dire in general (cheap Chinese omnis claiming >5dBi are lies 
generally) One 5dBi one did work ok.

To test I used a modified PCI card to affix the antenna to.

The best of the bunch were two:

A simple 5dBi TP/link 'ducky' antenna with an adhoc parabolic reflector:

http://www.freeantennas.com/projects/template/

This simple foil reflector gave a meaningful boost of signals.


The best so far is a thing I knocked up from scrap yesterday and have 
finalised today. Made from 2mm mains flex solid ground wire, mdf, a 
strip of beech for rigidity, some bolts and scrap sheets of steel.
It is called the AMOS antenna and isn't too difficult to make, unlike 
most of the other designs out there that almost certainly need expensive 
equipment to get right. This has a wide beam of about 120 degrees. Real, 
measured with network stumbler, boost in SNR on a known signal was about 
10dBm above the cheap antenna with adhoc para' reflector!
So I guess it is working pretty much as it should.
Picks up much more of the surrounding AP's.
My brain is microwaving, can you see it wave? ;)

http://www.qsl.net/yu1aw/vhf_ant.htm

Supposedly the inverted AMOS is better and no more difficult.

A commercial equivalent that works would be rather expensive.