In this paper, a miniaturized dual-band planar monopole antenna is studied. The aim of this study is to incorporate two different communication standards in a single device. The simulation analysis was performed using the HFSS which is based on Finite Element Method (FEM) and CST which is based on Finite Integration Technique (FIT). The proposed antenna is formed by a CPW feed line and a rectangular ring monopole with a vertical strip. The designed antenna has a small overall size of 19 mm (width) × 36 mm (length) × 1.6 mm (thickness). A prototype of this antenna was fabricated. The measured results indicate that the antenna has the impedance bandwidths of 650 MHz (2.30-2.95 GHz) and 2460 MHz (3.40-5.86 GHz) at the first and second bands, respectively with a reflection coefficient less than -10 dB covering all the WLAN bands (2.4/5.2/5.8 GHz) and WiMAX bands (2.6/3.5/5.5 GHz). In addition, the nearly omni-directional and bi- directional radiation patterns are also achieved in both H- and E-planes, respectively. It is also noticeable that a good antenna gain over both operating bands has been obtained. Hence, it can be inferred that this simple compact planar monopole antenna with multi-band characteristics is suitable for WLAN and WiMAX communication applications.