A dual-sense CP MIMO antenna using decoupling structure with improved isolation

This paper aims to design and fabricate a circularly polarized MIMO antenna with opposite rotating senses and use a new decoupling element to improve the isolation between the antenna ports. The proposed design includes two pairs of crossed-dipoles fed by two branch-line couplers to accomplish a dual-sense CP MIMO antenna. The elements used in this design are printed dipole antennas with balun feeding. As a validation, an antenna prototype is fabricated and measured. The experimental results show that operating bandwidths of the antenna are 32.98 % (1.95–2.72 GHz) and 29.17 % (2.02–2.71 GHz) with |S11| < 10 dB for Port-R and Port-L respectively, with axial ratio bandwidth of 1.97–2.51 GHz at the two ports. Furthermore, measured results approve that by employing the decoupling component, at least 15.2 dB isolation between the ports with an ECC value of less than 0.0037 in the operating frequency band is achieved. According to the results, the proposed design in this study is a good candidate for 2.4 GHz frequency ISM and WLAN applications with CP operation.