Two-Element Wideband CP Meta-Surface MIMO Antenna With H-Plane Coupling Suppression

Abstract

This work presents a novel wideband circularly polarized (CP) multiple-input-multiple-output (MIMO) antenna scheme featuring a two-cluster meta-surface structure with integrated shorting-pin vias, specifically designed for nextgeneration Internet of Things (IoT) applications. The proposed antenna consists of two substrate layers: the upper layer accommodates the 12 corner-truncated square meta-surface elements, while the lower layer implements a dual-element coplanar waveguide (CPW) feeding network. A strategically positioned shorting-pin via, acting as a magnetic wall, is incorporated between clusters to suppress H-plane coupling. The antenna prototype achieves a measured return loss bandwidth (RLBW) of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{4 6. 7 2 \%} \boldsymbol{(} \mathbf{4. 2}-\mathbf{6. 7 7 ~ G H z} \boldsymbol{)}$</tex>, an axial ratio bandwidth (ARBW) of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$11 \%(5.29-5.9 \text{GHz})$</tex>, and a peak realized gain of 5.82 dBic at 5.5 GHz. Furthermore, the design exhibits excellent isolation (<tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$&gt;25 ~\text{dB}$</tex>), an envelope correlation coefficient (ECC) below 0.002, and a diversity gain (DG) exceeding 9.99 dB. These results affirm the effectiveness and suitability of the proposed antenna scheme for IoT communication systems.