compact microstrip patch antenna with two U-slots shape is presented. Detailed simulation and experimental investigation are conducted to understand the behavior of the two U-slots. The proposed antenna generates three resonant frequencies at 2.7, 3.3, and 5.3 GHz. It can, therefore, be used in Worldwide Interoperability for Microwave Access compliant communication equipment. The proposed antenna has two U-slot shaped and two bridge elements to connect both shapes together to adapt the structure to the desired interest operating frequency. A comprehensive parametric study has been applied to understand the effect of each U-slot on the antenna's performance. Moreover, the current distribution for the three bands is investigated to give further understanding of the antenna behavior. The proposed antenna is verified experimentally and the simulated and measured results are in good agreement.