Enhancing Radiation Characteristics of Antenna Arrays Over a Sparse Area

This paper presents the design of a 2×2 Circularly Polarized (CP) patch array operating in the X-Band frequency range. The array incorporates a Sequentially Rotated (SR) phase feed and utilises a metasurface-based superstrate fed by a parasitic aperture-coupled feeding network. The superstrate comprises an 8×8 array of asymmetric square metallic patches etched on a dielectric substrate, positioned at half-wavelength from the CP array. The proposed design offers significant advantages, including a broad 3-dB Axial Ratio (AR) bandwidth of 39%, high-directivity of 15 dBi, and wide 3-dB directivity bandwidth of 42.5%. Moreover, this antenna design leverages the use of sequentially rotated slots in superstrate-based antennas, making it suitable for implementation over sparse areas.