Wideband Circularly Polarized Substrate-Integrated Waveguide Aperture-Coupled Metasurface Antenna Array for Millimeter-Wave Applications

A wideband circularly polarized (CP) aperture-coupled metasurface antenna operating at millimeter-wave frequency spectrum in substrate-integrated waveguide (SIW) technology is proposed. The proposed metasurface antenna is composed of two substrates. The first substrate contains an end-shorted SIW section with a slot etched. The introduced metasurface is printed on the top of the second substrate. The metasurface is comprised of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$3 \times 3$</tex> unit cells, each of which contains two interconnected patches and two parasitic patches. The working mechanism of the proposed metasurface antenna is illustrated in details. The proposed metasurface antenna has wide impedance bandwidth and axial ratio (AR) bandwidth, which are 66.7% and 40%, respectively. Using the proposed metasurface antenna, a <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$4 \times 4$</tex> CP metasurface antenna array with an impedance bandwidth of 24%, an AR bandwidth of 30%, and a peak gain of 18.7 dBic in simulation is developed in this paper for millimeter-wave applications.