In this article, we propose a microstrip-fed printed meandered log-periodic monopole array (PMLPMA), and its dual-port configuration incorporating an octagonal ring frequency selective surface (FSS) layer. The dual-port PMLPMA antenna system has a compact structure with a total dimension of 18.75 × 18.75 mm2 and is designed to operate in the 5G n257 (28 GHz) band. The proposed PMLPMA radiator consists of five log-periodic monopole array elements, and the dual-port antenna system comprises two identical PMLPMAs placed vertically next to each other. Additionally, an octagonal ring-shaped single-layer FSS was implemented on the proposed antenna system to increase the gain across the operational band. Simulation results demonstrate that the dual-port PMLPMA antenna achieves a peak gain of about 3.5 dBi without the FSS layer, while a peak gain of 7.35 dBi is achieved when the FSS layer is augmented on the antenna. Moreover, isolation levels exceeding 30 dB are obtained for both cases between the 26.5–29.5 GHz frequency ranges. To verify the simulation results, the dual-port PMLPMA antenna system, and the octagonal ring-shaped FSS layer are also prototyped. The measurements align closely with the simulations in terms of performance criteria such as gain, bandwidth, and radiation patterns. Thus, the 28 GHz band antenna system exhibits great potential for 5G mobile applications.