Wideband Phase-Gradient Metasurface Antenna With Focused Beams

A transmitting lens antenna with focused beams by employing four-layer phase-gradient metasurface (PGMS) is proposed. A wideband slot-coupled antenna is mounted close to the focal position of the PGMS acting as a feed. The electromagnetic wave radiated through the feed source is transformed to plane wave within a wide frequency covering from 9.4 to 10.6 GHz. The in-band measured gain is from 16.7 to 19.4 dBi and a 3-dB gain bandwidth of around 10% is achieved, which demonstrates that the proposed four-layer PGMS still has the ability to focus electromagnetic wave within a wide frequency band efficiently though its transmission phase range at some specific frequency bands does not meet 360°.