Low-Profile Dipole Antenna Integrated With Wideband Polarization Converter

This paper presents the design of a low-profile dipole antenna integrated with a wideband polarization converter metasurface. The antenna consists of a modified dipole structure that includes two parasitic patches placed on the bottom side of a single-layer, ultra-thin substrate in a coplanar configuration. A 2 x 2 metasurface array is positioned on the top side of the substrate to convert linear polarization to circular polarization. Each unit cell of the metasurface consists of a complementary patch structure formed by etching out two diagonally oriented striplines from the metal square patch, resulting in a distinct chiseled pattern. These diagonal striplines are essential for creating 90 degrees phase difference and achieving near-equal amplitude between orthogonal polarization components. The proposed antenna achieves a wide axial ratio (AR) bandwidth of 42.1% (4.06-6.22 GHz) and an impedance bandwidth of 44.2% (4.06-6.36 GHz), with a peak gain of 3.2 dBi at 5.2 GHz and a radiation efficiency of over 95% within the AR bandwidth.