Design and analysis of a high-isolation metamaterial-inspired MIMO antenna with defected patch structures for improved sub-6 GHz band performance in 5 G wireless applications

• A compact 4-element MIMO antenna is designed using CSRR-based metamaterials and defected patch structures for enhanced sub-6 GHz 5G performance. • Achieves high isolation (>23 dB), low ECC (∼0.0029), and high diversity gain (∼9.98 dB), ensuring robust spatial diversity and minimal mutual coupling. • Offers consistent performance across key metrics—TARC (< -10 dB), CCL (< 0.4 bits/Hz/sec), ME (∼0.65), and group delay (< 1.5 ns)—making it ideal for high-speed wireless communication. • Experimental validation confirms strong agreement with simulations, endorsing the antenna's reliability for practical 5G MIMO applications. This paper presents the design, experimental validation, and comprehensive performance analysis of a compact 4-element Multiple-Input-Multiple-Output (MIMO) antenna with the dimension of 0.80 λ×0.48 λ×0.027 λ, specifically optimized for Sub-6 GHz 5G wireless applications. Operating at a central frequency of 5 GHz, the proposed antenna leverages vertical columns of periodically arranged Metamaterial unit cells, each embodying a Complementary Split Ring Resonator (CSRR) structure, to significantly enhance inter-element isolation. The design directly addresses the persistent challenge of minimizing mutual coupling while maintaining compactness and high radiation efficiency in multi-element antenna systems. The fabricated prototype demonstrates a measured peak gain of 5.04 dBi at 5 GHz, achieving excellent isolation (>23 dB) and a high diversity gain (>9.98 dB) across the entire operating band. Furthermore, the mean effective gain (MEG) consistently remains within the acceptable range of ±3 dB. Rigorous analysis of scattering parameters, radiation patterns, surface current distribution, and key diversity performance metrics—including Envelope Correlation Coefficient (ECC), Total Active Reflection Coefficient (TARC), Channel Capacity Loss (CCL), Multiplexing Efficiency (ME), and Group Delay (GD)—confirms the antenna's robust performance and suitability for high-speed, reliable wireless communication. The strong agreement between simulated and measured results validates the design's accuracy and its potential as a high-isolation MIMO solution for next-generation wireless systems.