SADEA-optimized metasurface antenna for broadband circular polarization in sub-6 GHz 5G systems

In this work, a high-gain broadband circularly polarized (CP) metasurface-based printed monopole antenna is proposed for sub-6 GHz 5G covering ambient RF energy harvesting applications & next-generation wireless connectivity links. It starts from a λ_o/4 linearly polarized (LP) printed monopole and attains its CP by connecting parasitic conducting strip (PCS-L) to partial ground plane with a metallic shorting strip. Thus, this perturbation changes the distribution of surface currents and makes it possible to excite degenerate orthogonal modes with quadrature phase. With a couple of metamaterial unit cells embedded on the monopole radiator & metasurface (MTS) layer as a reflector that is optimized by using self-adaptive differential evolution algorithm (SADEA), it is meant to improve 10-dB impedance and 3-dB axial-ratio bandwidths, with broadened CP gain at the same time. The SADEA-driven optimization effectively navigates high-dimensional MTS design space, resulting in enhanced performance while simplifying the entire design process. The MTS is placed at a height of 20 mm below the radiator. This changes near-field coupling & phase evolution, which offers the broadband CP radiation with directional features. The final antenna is printed on FR-4 substrate with dimensions of 80 × 59.5 × 1.6 mm³ shows a measured 10-dB impedance bandwidth of > 45%, a 3-dB axial-ratio bandwidth of > 15%, an average CP gain of > 8 dBic, a radiation efficiency of > 80%, & a front-to-back ratio (FBR) of > -21 dBic, validating the effectiveness and scalability of the proposed methodology for the designing of broadened CP printed monopole antennas aimed for sub-6 GHz 5G systems.