Highly compact size serpentine‐shaped multiple‐input–multiple‐output fractal antenna with CP diversity

Abstract

A novel multiple-input-multiple-output fractal antenna was proposed in this study. The proposed antenna consisted of two symmetrical radiating elements placed on opposite sides to achieve spatial diversity with a highly compact size (8 × 8 × 0.8 mm 3 ). Each radiating element is configured by a process of three iterations, and an additional semi-crescent structure scaled down in each iteration placed in a cascade arrangement. This arrangement generated circularly polarised radiation with an axial ratio bandwidth of (2.2-3.2) GHz, which was about 24% of the entire operational range of (0.1-4.3) GHz that can be used for many wireless communications such as long-term evolution, radio-frequency identification, wireless fidelity, and worldwide interoperability for microwave access applications. The envelope correlation coefficient, mutual coupling, circular polarisation (CP), and current distribution were studied and analysed to improve the design process. Compared to other related antennas, the proposed antenna can improve many radiation characteristics such as diversity (left-hand CP) and (right-hand CP), wide axial ratio bandwidth, and acceptable gain in a small antenna size.