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.
Pictures are from this site starhill.org
Interesting design as You can see.
There are four stacked biquads or bicircles over a corner reflector.
Here is a PDF file whit a dimensions of this wifi antenna : 12dB_sektor_antena.pdf
Interesting moments are grounding and feeding of the circle elements - you can see this here :
I never sow biquads to be grounded or feeded like this.
Some photos of my 5ghz slotted waveguide antenna project - never finished and tested due lack of proper hardware to test.
Made from aluminum tube and calculated whit hlssa program.
This is ten slots dual side design.
As I maybe mentioned in my previous post hlssa program gives some very strange results about thickness dimensions of the waveguides. The program says that is passable to build slotted waveguide whit an only 100mm to 25mm tube or waveguide for 2.4ghz band.
Till now I was unable to find anything that confirm this, but now I sow several interesting pictures :
Pictures are from here : www.starhill.org
Look at this - there is NO WAY that this is be 100×50 mm this looks like more like 20 or 25mm !!! 
So this will make passable to use other, more easy to be found on the market tubes.
More pictures :
And finally one more thing - 20 to 22dbi omni directional slotted waveguide 25mm thin PDF file whit specification
