Where i can get formulas for microstrip patch "element pattern" or "element factor"?

Hello! I used formulas for calculating AF (antenna factor), and after some trial and error get results that match measurements very well. For example, side beams angular position. To calculate approximate radiation pattern i must multiply AF by element pattern. I am unsure how this thing called. When element pattern can cancel out AF side beams, or AF pattern cancels out element side beams. I want to find some approximation formulas of single rectangular patch radiation pattern, or maybe circular patch radiation pattern. Thanks!

p.s. I found similar question without answer here. He explained problem better than me:
Thread link: https://www.edaboard.com/thread171869.html



i found an answer here:
http://www.antenna-theory.com/antennas/patches/antenna.php
and here:
http://valab.det.unifi.it/new/material/UNIFIvallecchi02/Rectangular_patch.pdf