help antenna project hfss

hi everyone,i have a project in hfss , i get good wsvr and s11 values but i cant have directivity and gain as i want. i uploaded my project here can anyone say what is wrong with my project ? Project9,101.rar

one more question , while s11 value of a frequency point is big , gain is same proportional small. why is ti like that ?

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i meaned for example at 5.5ghz s11=-20db gain is about 0.8 at 6.00 ghz s11=-3db gain is about 2