How to design an antenna to operate at 3 and 5 GHz?

i am working on microstrip patch antenna...i gonna design antenna to operate at 3 and 5 GHz...but my design gives just 2.3 and 4.5....i want to shift or modify s11 to the desired values 3 and 5 GHz..
is there any suggestion to solve such case....
here attachment for s11 graph on hfss 15.

If you want to get two resonance with patch antenna, the best way would be to first design a patch resonating at 3 GHz and then add a slot to make it dual band. The dimensions of the slot can be so adjusted that the antenna has a second resonance at 5 GHz

thnx a lot Umar608 the substrate thickness and material type were the most important parameters.

you need to reduce dimension patch antenna.

it s impossible to achieve this BW at this frequency
try other antenna

Try smaller patch dimensions.