Hello
There are a set of design equations for length and width of the patch
Resonant Frequency=(3*10^8)/(2*Length*sqrt(epsilonr))
you should be able to calculate the length from here,in the above equation epsilonr represents the dielectric of the material.
Thickness of copper affects your impedance values,so matching can be a issue.but this is only for higher frequencies. at around 2GHz the impedance difference between .5 ounce and 1 ounce is around 2 ohms
Hope that was helpful.
Regards
Sajid Mohammed.