Here one very interesting antenna - La Fontenna Clone.
It was interesting what is inside FON antenna. On site specs they give it 7dbi or 6.5dbi with 3m low loss coax.
On one Italian blog I found dimensions for building a clone of La Fontenna.
Quasi Log Periodic End Fire Array (QLP) Feed Antenna
Specification :
http://www.calamp.com/pro_mmds_130093-130120.html
Page 5 lan23.ru
http://www.lan23.ru/forum/showthread.php?t=5&page=5
http://www.wireless-homebrew.com/wireless/page04.html
russians again
http://www.nag.ru/2003/0110/sirco-text.html
some pictures :
http://hft.uni-duisburg-essen.de/INICA2007/2003/archive/inica_2003/P06_Ibrahim.PDF
One of these build on lan23.ru
Here dimensions of my one :
http://www.digdice.com/2008/02/07/qlp-antenna/
How to make our own reflector :
http://www.digdice.com/2007/08/31/diy-hi-gain-antenna-on-cheap/
What is Polaplexer ?
“… The Polaplexer is a microwave antenna, or antenna feed, which supports two
simultaneous inputs or outputs that are independent and isolated from each other by use
of orthogonal (at right angles) linear polarization. The isolation can be as much as 30 -
35 dB. Its main use is to permit full duplex operation with a single antenna, in which one
port is used to transmit and the other to simultaneously receive. As long as the transmit
power input to the Polaplexer is limited to 100 milliwatts or so, the receiver input stages
are unlikely to be damaged by the transmitter’s continuous output. …”
I never met this thing before it just came out from no were ! If anybody was tried this please post a comment.
http://www.ham-radio.com/sbms/sd/ppxrdsgn.htm
For me is interesting can I use two wifi cards working on different channels with one antenna and this thing?
QLP Antenna
Freq around 2.4GHZ 
and back side 
