Abstract—In this research, a novel dual-band antenna is proposed to operate at resonant frequencies of 28 GHz and 38 GHz, which are significant for millimeter-wave 5G applications such as smart cities and the Internet of Things (IoT), utilizing an FR-4 substrate. This study employs a Complementary Split Ring Resonator (CSRR) in conjunction with a Defected Ground Structure (DGS) to achieve dual-band resonant frequencies. This innovative approach enhances key performance metrics, facilitating efficient operation across multiple frequency bands, particularly bandwidth and S11 value. The proposed antenna demonstrates significant improvements, offering an impedance bandwidth of 4.63 GHz and 4.66 GHz for the 28 GHz and 38 GHz bands, respectively. Notably, we obtain an S11 value of −25 dB in the first band (28 GHz) and an S11 value of −70 dB in the second band (38 GHz), demonstrating excellent performance. The directional characteristics of the antenna are evident in the E-plane pattern, focusing the signal in a specific direction. Conversely, the H-plane layout provides omnidirectional coverage, ensuring signal dispersion in all directions. Furthermore, to introduce reconfigurability, Positive Intrinsic Negative (PIN) diodes are integrated to alter the resonant frequencies and radiation pattern direction, enhancing the antenna’s adaptability. The design process utilizes Computer Simulation Technology (CST), with validation performed using High Frequency Simulation Software (HFSS) to ensure the accuracy and reliability of the results.