Here one small antenna witch I have from a long time. I am happy from it – I use it on 5.3ghz band and it works well – it gives what is promised.
Not like omnidirecional trendnet antenna – whitch I do not like
Some specs :
Name : Dual-Band 11a/g 8/6dBi Indoor Directional Antenna w/ Mounting TEW-AI86DB / mine is not with mounting but the PCB and specs are the same /
Gain : 802.11b/g: 8dBi 802.11b/g: 6dBi
VSWR : 2.0:1
Polarization : Linear, Vertical
Horizontal : 802.11a: 50° 802.11b/g: 75°
Vertical : 802.11a: 60° 802.11b/g: 70°
Dual-Band 802.11a/g 8/6dBi Indoor
You can find documentation on trendnet site.
And some scans of the pcb of this wifi antenna