why do you need the group delay of the antenna??

In order to understand the pulse distortion in UWB antenna  transmission, I need  it

i know just this way. is it ok for you?

 in project manager window, right click results->create modal solution data report -> rectangle plot. category group delay primary sweep frequency.

Thank you for your response.  I need to find the group delay in terms of S21.

so i think you should dfine a new variable in hfss and write its equation  according to the s_21 phase. 

Hello, azita gudarzi... To find the group delay i have taken two identical UWB antennas separated by a distance of 30 cm with face to face orientation. after simulation i did the following steps  results->create modal solution data reports-> rectangular plot->group delay-> groupdelay(2,1)-> abs-> new report. is that correct ? or should i use the Matlab to find out the group delay from the standard expression.

Dear Harsha,

The procedure you mentioned is correct.......

You must select group delay with S(1,2) or S(2,1) since we need delay from port 1 to port 2 or vice versa.