I don’t like Yagi antennas /sorry/, and I never try to make one , but this look interesting – it is only one side pcb design that differ from the most dual sided similar.
On the side is said that this antenna is a clone to a commercial one, but not a name or model is mentioned.
The dual sided board is needed to make the feeding point of the yagi antenna – here we have something very interesting and different to be able to make all needed parts on one sided PCB board. In fact this is dipole.
Link to the page : http://www.aribg.it/Tech/WiFi/Yagy24ydm/yagi24ghz.htm
Here is schematic :
Here some pictures whit dimensions :
On the second picture You can see haw to assemble the dipole – this is the interesting part. This antenna is feeded by dipole not whit loop like most Yagi antennas. Here they make a balun whit the stripped coax and the pcb board.
There is also one aluminum disk used to hold the board that is used as reflector :
On the site is said that this antenna have 11.5dB gain. And for last there is a SWR test for this antenna pretty good results I thing :
The peek is little out of wifi band but we still may get very good results for wlan applications.