Sharif University of Technology Scientia Iranica 1026-3098 Articles in Press 2025 12 20 Design Compact Dual Band EMSIW MIMO Antenna with Improved Higher-Order Mode Radiation Pattern 24109 10.24200/sci.2025.66423.10193 EN Nidhi Yadav Department of ECE, Malviya National Institute of Technology, Jaipur, India Rajendra Prasad Yadav Department of ECE, Malviya National Institute of Technology, Jaipur, India M. M. Sharma Department of ECE, Malviya National Institute of Technology, Jaipur, India 0000-0001-9892-636X Journal Article 2025 04 30 In this paper, a compact dual-band eight-mode substrate-integrated waveguide (EMSIW) MIMO (Multiple-Input Multiple-Output) antenna is presented for S and C band applications. By utilizing the EMSIW approach, the electrical size of the antenna is reduced to 1/8th of a conventional square SIW cavity resonator. The eight-mode configuration preserves the dominant mode at the same frequency, while significantly reducing the antenna size. The dominant mode resonates at 2.5 GHz, and a higher-order mode operates at 5.8 GHz by incorporating a slot in the design. To improve the radiation pattern at 5.8 GHz, the surface current nulls near the center of the EMSIW patch are reshaped, enhancing broadside radiation. The 2x2 MIMO antenna is designed to minimize mutual coupling by maintaining specific electric and magnetic wall configurations, ensuring minimal electric field interaction between the antenna ports. Fabricated on a low-cost FR4 substrate, the proposed MIMO antenna demonstrates excellent agreement between simulated and measured results. This compact design is a promising solution for satellite S-band and C-band applications, offering enhanced higher-order mode radiation performance and minimal mutual coupling. https://scientiairanica.sharif.edu/article_24109_e1d351219a44905eb5f80749d63ce379.pdf