A Wideband High-Gain Circularly-Polarized Metasurface Antenna with a Large Element Spacing SIW Array at Ka Band

In this paper, a novel Ka-band circularly-polarized (CP) planar metasurface antenna is proposed, which is based on an innovation technique for suppressing grating lobes in antenna arrays featuring large element spacing (LES). It consists of two essential components: a substrate-integrated-waveguide (SIW) array with an element spacing of
$2\lambda$
and a metasurface lens (meta-lens). The LES SIW array and the compact transparent-like meta-lens are first developed separately, to achieve CP performance with grating lobes and circular-to-circular polarization transformation with continuous compensation phases, respectively. They are then integrated to construct the metasurface antenna, where the grating lobes from the SIW array are effectively suppressed and the gain is significantly improved. Simulations are carried out to validate the antenna design, yielding impressive results, including a peak gain of 26.92 dBic and an expansive 3-dB axial ratio (AR) bandwidth of over 23 %. This innovative antenna design provides an alternative way to realize high-gain antenna arrays, offering distinct advantages of design simplicity and the ability to overcome difficulties associated with processing, tuning, and reliability, especially in the millimeter-wave band.