help needed in design of reflectarray antenna

hi, i am working on a paper titled
"Design of a Near-Field Focused Reflectarray Antenna for 2.4 GHz RFID Reader Applications
Hsi-Tseng Chou; Tso-Ming Hung; Nan-Nan Wang; Hsi-Hsir Chou; Chia Tung; Nepa, P.;
Antennas and Propagation, IEEE Transactions on Antennas and Propagation...

i am using CST studio, since iam new to it i need some help in simulating the reflectarray. can anyone help me by giving any example of reflectarray antenna which was simulated....thanks in advance...