patch antenna for 100 MHz in HFSS

hi everybody i have designed a patch antenna in HFSS for 100 MHz i am getting fine RL at 100 MHz but the other antenna parameters gain, directivity etc. are not quite well , i am unable to understand this problem can anyone help me in this regard please, my email id in engineermohsinali@gmail.com, if any expert is interested i can send him my design for further analysis