In this chapter, a two-port reconfigurable electric-inductive capacitor (ELC) metamaterial multi-input-multi-output (MIMO) antenna for C-band applications is designed. A compact ELC metamaterial characteristics with dimensions of 0.1λ × 0.1λ are analyzed. The proposed MIMO antenna incorporates two-port compact ELC metamaterial configurations with a defected ground structure (DGS) to enhance bandwidth. A specific complementary split-ring resonator (CSRR) array is incorporated into the DGS ground plane to improve isolation between the radiating elements. Moreover, the CSRR array minimizes robust magnetic coupling among radiating elements by producing antiparallel currents at operational frequencies, boosting isolation greater than −25 dB. The proposed two-port ELC metamaterial MIMO antenna is designed with an overall footprint of 0.26λ × 0.38λ on a FR4 dielectric substrate (dielectric constant εr = 4.4). Reconfiguration is attained by inserting two PIN diodes between the capacitance plates of the ELC structure, allowing four unique states of the antenna response. Each diode state modifies the antenna’s electromagnetic properties, including resonance and isolation. The proposed two-port ELC metamaterial MIMO antenna covers the entire C-range (4–8 GHz) in addition to a lower range from 3 to 4 GHz, making it suitable for multiple C-band applications. The design satisfies with industry standards for MIMO performance, showing computed diversity metrics including an envelope correlation coefficient (ECC) below 0.01, diversity gain (DG) of approximately 10 dB, and total active reflection coefficient (TARC) under −10 dB, ensuring robust diversity performance for MIMO C-band applications.