Dual-Band Printed Near-Field Metasurface with Independent Phase Transformation for Enhanced Antenna Gain

This letter proposes a near-field dual-band printed metasurface (DBPM) to realise a high-gain front-end antenna for full-duplex Ka-Band communication systems. The base of the antenna is a shortened horn, and DBPM is placed on its face to improve uniformity in its near-field phase distribution. The fundamental cell of the DBPM uses two distinct resonating elements, a cross slot, and a square slot, to have independent phase control at both frequency bands, increasing the gain of the horn and resulting in half the length of the antenna system as compared to a conventional horn antenna with a similar gain value. Measurements of the prototype reveal outstanding radiation performance, with a wider 3-dB gain bandwidth of almost 15% at the lower frequency band and 3% at the higher frequency band. Furthermore, the antenna gain is increased by 12-13 dB in each band. The total longitudinal height of the antenna, including the DBPM, is $2.5\lambda _{L}$ and $3.75\lambda _{H}$ , where $\lambda _{L}$ and $\lambda _{H}$ are the free space wavelengths at the lower and higher frequencies, respectively, while the aperture diameter is 8.4 $\lambda _{H}$ . The motivation of this research aligns with the demands of modern connectivity solutions, providing a simplified manufacturing approach for designing compact and full-duplex high-gain antenna systems.