Due to the recent developments in the domain of wireless network, the demand of multi frequency antenna has increased significantly. Wi-Fi has become a very popular choice available to the end users, providing them broadband connectivity and an alternative to cable and digital subscriber line, while X band finds extensive use in RADAR and satellite communication systems, and the proposed design can be put to use where there is a need for integration of both technologies. In this study, the authors have developed a novel U-shaped slot antenna for Wi-Fi and X band applications which gives a significantly higher gain and better performance than the existing antennas aimed for the same application to validate the model the structure was simulated in HFSS and operating frequencies for the proposed antenna were in compliance with the IEEE 802.11 WLAN protocol and the X band range. The structure has a fairly simple design and is having a fairly compact dimension of 40 mm × 40 mm × 1.6 mm. Moreover, the obtained radiation pattern demonstrates that proposed antenna has a significantly unidirectional pattern in both E-plane and H-plane. In addition to the unidirectional radiation pattern, a significant reduction in conduction loss was obtained. © 2018, Springer Nature Singapore Pte Ltd.