chosing patch antenna geometry

I'm a student and I must design an antenna that cover 3 bands
I read so much books about antenna
But my big problem is that I don't know exactly which geometry I must chose and why this one and not another one
i don't know how to start my design and what I'll depend on firstly
if anyone can guide me I will be grateful to him.
thanks

Hello Ahmad,
Firstly if you have gone through Antenna design books you should be well aware about the geometry and dimensions of the antenna. There are many books : Antenna Theory- C. Balanis is the one i would prefer.
Next you can try implementing that structure in any 2D-3D antenna simulator to verify the designed antenna covers your desired 3 bands. You can modify the geometry and can see its effects on your results.
Enjoy..

go through Antenna Theory balanis Chapter 14.

thanks
I tried to download this book but I didn't find any free copy
if there is any free copy please paste the address