For PTP820 NA customer, we use Commscope Valu-line dish, and Radiowave HP dish.
If you know the antenna size and frequency. For example, 11 GHz, 3 ft, you will be able to find a general spec from manufacturer's web page, which will tell the antenna gain, pattern, etc.
http://www.commscope.com/catalog/wireless/2147485870/product_narrow_antmicro.aspx?id=441
Basically you choose the antenna size, frequency, then choose the antenna type, (VHLP for Andrew, HP Parabolic for Radiowave), you will get the spec and other technical document related to this antenna.
thanks
Allen