resonence

hi............frnds
....i m working on designing of microstrip antenna of 2.4 Ghz
having some problems
1st...is there any effect of cell size on the -ve reflection response?
2nd..i have calculated all dimenssins of patch, feedline and transformer..for a resonent freq 2.4 ghz but still getting response at 2.35 ghz ........
by changing which parameters in design i can shift my response at 2.4 ghz....

thanks...