A novel and compact design of dual-band antenna, based on substrate integrated cavity is developed. The antenna comprises a half-mode cavity, an open-ended longitudinal slot, and a printed inset-feed mechanism. Finally, the proposed design is fabricated and its results are validated. It shows the measured impedance bandwidths of 3.51% and 1.40% at 8.8 and 11.2 GHz, respectively. Their corresponding peak gain values of 5.04 and 5.01 dBi. The results of the fabricated antenna in terms of bandwidth, gain, and radiation patterns are in close agreement with their simulated counterparts. On the account cavity-backed design, the antenna exhibits unidirectional and stable radiation patterns in both bands. Moreover, the uniplanar design gives additional flexibility of easy integration with other active/passive circuits. The proposed antenna can be a suitable candidate for dual-frequency operation in X-band (8-12 GHz), especially where small frequency-ratio is stringent. © 2020 Wiley Periodicals LLC