The rapid growth of technology increases the demands of low profile and compact antennas, supporting different wireless systems standards in mobile devices. Recently, several multi-band antenna designs have been proposed for mobile devices due to the current advancement of antenna technology. In this paper, a multi-band circular ring with a double L-shaped monopole antenna for Wireless Local Area Network (WLAN) and Worldwide Interoperability for Microwave Access (WiMAX) applications is presented. The proposed antenna consists of a circular-shaped and rectangular strip connected with two inverted L-shaped trips. The H-shaped-strips are attached within the rectangular-strips. The antenna is fed by a 50 Ω micro-strip line, and it operates at three resonant frequencies, which include 2.4 GHz and 3.5/5.5 GHz for WLAN and WiMAX applications, respectively. The antenna has been simulated using CST Microwave Studio software. The proposed antenna achieved impedance bandwidth of 284 MHz, 368 MHz, and 1120 MHz for 2.4 GHz, 3.5 GHz, and 5.5 GHz frequency bands, respectively, while the corresponding antenna gains are 1.28 dB, 1.78 dB, and 2.78 dB. The antenna has a compact dimension size of 18 x 28 x 1.6 mm3 when printed on the FR-4 substrate of dielectric constant 4.3.