An omnidirectional compact antenna based on dual-band Split Ring Resonators (SRRs) for 2.45 GHz wireless local area network (WLAN) and 3.5 GHz worldwide interoperability for microwave access (WiMAX) applications is presented. Different and new properties of SRRs, such as dual-band or multi-band performance in the design of compact antennas, can be obtained by making the rings unequal and asymmetric. The dual-band SRR antenna is designed with a bandwidth control technique based on the stored electromagnetic energy in the resonator rings. The obtained results show that the SRR antenna has good omnidirectional radiation pattern for both bands and good impedance bandwidth. In addition, compactness and flexibility are obtained with a simple structure of the SRRs.