New design of microstrip patch antenna at 28 GHZ and $$4\times 4$$ MIMO configuration with improved characteristics for IOT applications

This paper presents the design and analysis of a high-performance microstrip patch antenna operating at 28 GHz, along with a multiple-input multiple-output configuration optimized for beyond 5G and IoT applications. The proposed MPA incorporates a rectangular patch with two symmetrical L-shaped slots and a central rectangular slot, enhancing impedance matching and radiation characteristics. Fabricated using Rogers RT5880 substrate with a dielectric constant ( $${\varepsilon }_{r}$$ ) of 2.2 and a loss tangent of 0.0009, the antenna achieves a return loss of − 33.04 dB, ensuring minimal signal reflection and efficient power transfer. The simulated gain reaches 10.11 dBi, and the voltage standing wave ratio (VSWR) is measured at 1.04, indicating excellent performance. To further enhance system efficiency, a MIMO configuration is implemented, improving parameters such as return loss, isolation, and diversity gain. The MIMO system achieves gains of 10.2, 9.91, 10.2, and 9.84 dBi for individual elements, with a diversity gain of 10 dB, ensuring robust signal performance and increased data throughput. The design was fabricated and experimentally validated using a vector network analyzer, demonstrating strong agreement between simulations and measurements. These results confirm the antenna’s suitability for high-speed wireless communication in next-generation IoT networks.