MetaSlot-MIMO: A Compact Dual-Band Four-Port MIMO Antenna with Metamaterial-Inspired Decoupling Structure for 5G Millimeter-Wave Applications at 28/38 GHz
Keywords:
MIMO antenna; 5G millimeter-wave; Dual-band antenna; Microstrip patch; Complementary split-ring resonator; Decoupling structure; Envelope correlation coefficient; Channel capacity loss; 28 GHz; 38 GHzAbstract
The rapid deployment of fifth-generation (5G) millimeter-wave (mmWave) networks demands compact, high-isolation multi-antenna systems capable of supporting massive MIMO configurations at the standardized 28 GHz (n257/n261) and 38 GHz (n260) frequency bands. Existing dual-band MIMO antenna designs suffer from trade-offs between miniaturization, inter-element isolation, radiation efficiency, and wideband impedance matching, often requiring complex decoupling structures that increase fabrication cost and overall footprint. In this paper, we propose MetaSlot-MIMO, a compact four-port dual-band MIMO antenna system incorporating a novel metamaterial-inspired complementary split-ring resonator (CSRR) decoupling structure etched into the ground plane. The proposed antenna is fabricated on a Rogers RT/Duroid 5880 substrate (εr = 2.2, tanδ = 0.0009) with a total footprint of 26 × 26 × 0.254 mm³. Each radiating element is a modified rectangular microstrip patch with an L-shaped parasitic strip that enables simultaneous dual-band resonance at 28 and 38 GHz. The CSRR decoupling structure suppresses surface wave coupling between adjacent ports without degrading radiation characteristics. Simulated and measured results confirm: return loss |S11| < −15 dB at both bands; port isolation |S21| > 35 dB at 28 GHz and > 38 dB at 38 GHz; peak realized gain of 8.7 dBi at 28 GHz and 10.4 dBi at 38 GHz; radiation efficiency exceeding 91% at both bands; impedance bandwidth of 2.4 GHz (26.8–29.2 GHz) and 3.1 GHz (36.5–39.6 GHz). MIMO diversity metrics confirm excellent performance: envelope correlation coefficient (ECC) < 0.003, diversity gain (DG) > 9.99 dB, channel capacity loss (CCL) < 0.08 bps/Hz, and mean effective gain (MEG) ratio within 0.4 dB at both operating frequencies. The proposed design is validated by comparison with eight state-of-the-art designs from the open literature and shows superior performance in isolation, gain, and compactness.
References
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