I suppose it really depends on how you design the patch antenna, and it is also related to the feed point of the signal.

But how to find positional theta and phi

It depends on the direction in which antenna is radiating...By selecting E and H plane (0 or 90) u can vary vary the values of theta to find out your answer

If you want to do it manually and get a clear picture of the radiation pattern:

1) generate a 3D polar plot of dB(GainTotal)

2) visually locate the theta and phi position(s) of maxima

3) generate a far fields report of db(GainTotal) vs theta for specific phi values (e.g. 0, 90 deg), which effectively gives you vertical 'slices' of the 3D contour - you can overlay these in a single plot

See the attached figures.

Geoff.

thanks Yiming Huo and Geoffrey Knott

Rahul Agrawal JI E AND H PLANE DEPENDS ON MODES OF ANTENNA, IS IT TRUE

In hfss, go to result>far fields report>rectangular plot>antenna params>peak gain(dB)>new report. U will get the peak gain at specified solution frequency...

Or if u want to plot gain vs freq; Ist plot the gain vs theta (sweep) or gain vs phi(sweep) and locate the phi and theta points from the plot for which the gain is max...Now selecting those values for phi and theta, plot the gain vs freq curve and u will get the peak gain at different freq. points.