A Wideband Beam Steering and Beamwidth Reconfigurable Antenna Using Coding Metasurface

This paper presents a wideband beam steering and beamwidth reconfigurable antenna operating at a center frequency of 3.5 GHz. The proposed antenna consists of a cross-slot serving as the source element, a 19 x 19 artificial magnetic conductor (AMC) acting as a reflector, and a 9 x 9 transmissive coding metasurface (TCMS) functioning as a phase gradient. The cross-slot antenna offers a wide bandwidth and produces a bidirectional radiation pattern. Incorporating a 19 x 19 AMC beneath the source antenna achieves a high gain unidirectional radiation pattern. Additionally, positioning a 9 x 9 TCMS above the source antenna enables control over the antenna radiation characteristics. The TCMS comprises individual unit cells integrated with PIN diodes. By controlling operating states of the PIN diodes, the proposed antenna achieves beam steering and beamwidth reconfigurability in the yz-plane. Main beam of the antenna is steered from -57 degrees to +57 degrees. The proposed antenna offers flexibility in beamwidth reconfiguration, operating in wide beam and narrow beam mode. In wide beam mode, the antenna exhibits a 3-dB beamwidth of 140 degrees providing broader coverage. Conversely, in narrow beam mode the 3-dB beamwidth narrows to 60 degrees resulting in a more focused radiation pattern. The overall impedance bandwidth of the antenna ranges from 3.09 to 3.70 GHz (17.96%) with peak gain ranging from 5.8 dBi to 8.47 dBi. The simulated and measured results of the proposed antenna are found to be in good agreement.