im working on dual band microstrip antenna. using two patchs

im working on dual band microstrip antenna. using two patchs and feed them by proximity feed. are the dimensions of the two patchs must be different to get two bands?

hey

it depends on the frequency bands. I made dual band patch using one patch, using two patchs, and using one patch and some passive elements.
if you want to use two patches it will be best if you will use different sizes, just be careful because the patch not radiating will introduce parallel impedance to the radiating one.