No / A novel printed diversity monopole antenna is presented for WiFi/WiMAX applications. The antenna comprises two crescent shaped radiators placed symmetrically with respect to a defected ground plane and a wideband zigzag neutralization line is connected between them to achieve good impedance matching and low mutual coupling. Theoretical and experimental characteristics are illustrated for this antenna, which achieves an impedance bandwidth of 54.5% (over 2.4 – 4.2 GHz), at a reflection coefficient < −10 dB, mutual coupling < −16 dB. An acceptable agreement is obtained for the computed and measured gain, radiation patterns, and envelope correlation coefficient. These characteristics demonstrate that the proposed antenna is an attractive candidate for the multiple input multiple output (MIMO) portable mobile devices.