big problem in designing unique microstrip(pat(ch)) antenna

hi
I have a very very big problem for designing a microstrip antenna. I have to design a unique shape of antenna that didn't design before.
I read so many papers and some book about microstrip antennas but.. !
unfortunately there is no a general way or general equations to desgin microstrip.
for example, I found some shape like bow-tie, E-shape, U-shape and etc. but there isn't any walk through in this papers.
in fact, my question is that how I can design a patch antenna ?

for example I want to design a circular antenna whit U-slot in the top and substrate FR4 ( lossy ) with ε=4.9 and substrate thickness of 1.6 mm. in frequency range of 1 to 6 GHz. how could I determine antenna dimensions, substrate size , U-slot size, slot location, type of feeding and feeding size and location so on ?!
Is there any software that calculate these for me ?
please help me. I have to simulate with CST and afterward fabricate it until next month.
best regards