In this paper, a co-axial fed double L-shaped slotted micro-strip patch antenna array is proposed for multi-band operation satisfying WLAN (Wireless Local Area Network) and WiMAX (Worldwide interoperability for Microwave Access) application. A single micro-strip rectangular patch antenna is designed with center frequency at 3.6 GHz for WiMAX application and it also reduces the resonance frequency using double L-slot on the patch from 3.6 GHz to 2.6 GHz, which is also suitable for WLAN (IEEE 802.11b standard frequencies from 2.23 GHz to 5.35 GHz) applications. A measured 7 dB gain is achieved with array (1×2) antenna. The bandwidth is increased up to 60% at upper band of operating frequencies than the single patch antenna. The simulation results such as radiation pattern, VSWR, gain, and return loss are simulated using Ansoft HFSS. Measured and simulated results of return loss for both single patch and array antenna are analyzed and presented.