CST - Broadband gain is not matching with a single freq. plot

Hello community,

I am simulating farfield from an antenna, and I also want to calculate broadband gain. I have defined the broadband monitor and post-processing template as shown in the attached pictures. But, the gain from a single frequency polar plot (pic. attached) does not match the broadband gain plot (pic. attached) at the same freq. Is there something I am doing wrong here?

Regards

Saurav

CST Studio Suite