Calculattion of gain versus frequency of patch antenna?

Hello,

I just have a question about calculating the gain versus frequency for a single rectangular patch antenna with a resonance frequency of 3.8 GHz by using CST MICROWAVE STUDIO 2009 software. I think I should use one discrete port for the single patch antenna as well as using some field monitors, but I am not sure if I should use farfield broadband calculation as well. In addition, sometimes I achieve negative gain which is a bit strange.I am wondering if anybody can guide me about it.

Thank you

Maryam

hai ... yes u should select broadband farfield monitor from macros and then u give start and stop frequency and step size, then simulate it will give u the gain for different frequech according to ur step size.

if resonance is not there it will show negative gain also, in that frequency.

Hi Jamesanton,

Thanks very much for your useful reply. Do you also suggest that I also go to Result/Template based processing and I choose farfield (broadband), then I start the simulation or there is no need to choose farfield(broadband) from template based processing?
In order to find the result of simulation should I look at the 2D/3D Results/Table?

I still have problem in understanding the reason of achiving negative gain.