A filtering-enhanced MIMO antenna architecture for next-generation multi-user satellite communication

In this paper, we present an innovative approach to interference mitigation in ultra-wideband (UWB) antennas through passive filtering techniques. The proposed design focuses on selective frequency rejection to ensure signal integrity across the 3–9 GHz spectrum. By implementing a dual-notch configuration, unwanted interference is effectively suppressed. Specifically, the first notch band, covering the 3.4–3.7 GHz range (WiMAX band), is achieved by embedding a complementary split-ring resonator (CSRR) within the radiating patch. The second notch band, covering the 5.8–7.2 GHz range (WLAN/Wi-Fi band), is realized using a split-ring resonator (SRR) etched in the ground plane. The design process begins with the development and optimization of a basic UWB antenna, validated through reflection coefficient and gain analyses. The CSRR cell is introduced in the radiating element to generate the first notch without degrading the wideband performance, while the SRR is strategically placed in the ground plane to establish the second notch. The resulting dual-notch configuration successfully reduces interference while maintaining strong performance across the remaining UWB bandwidth. The study is further extended to a multiple-input multiple-output (MIMO) antenna system comprising two elements. To enhance overall performance, particular attention is given to minimizing mutual coupling, a critical factor for high efficiency and signal integrity in MIMO configurations. An isolating structure is integrated between the antennas, significantly reducing mutual coupling and preventing undesired signal interference. These enhancements enable the MIMO system to support multiple simultaneous data streams, making it well-suited for modern wireless technologies, including 5G, Wi-Fi 6, and other high-data-rate applications.