power requirement for S band radar

I have to design an antenna for s band radar application, I have selected the stacked patch antenna for this purpose. my boss is asking me to take into account the power requirements of s band radar as well, how can i do this along with other parameters of antenna

thanks

What you need is a detailed knowledge of radar system. Antenna is only one part of it.

Read Skolnik or another radar textbook. On the forum it makes no sense to write long explanations.

Help on how to calc the patch antenna power handeling ?
Pls

How about simply check on FCC / ETSI limitations for your product, and use nearly maximum allowed power. You can always attenuate. And, as it says somwhere on the net, "remember, gain is cheap!" =)