Nonuniform Modulated Holographic Antenna With Wide Gain Bandwidth and Scanning Angle

The holographic antenna is an impedance-modulated periodic leaky-wave antenna. The radiation efficiency is higher in the region closer to the feed because of uneven leaky-wave radiations and thus limits the overall aperture efficiency. To alleviate this issue, this paper proposes a nonuniform proportional impedance modulation method. By employing directional-fed topology and controlling the leakage rate in different regions on the aperture surface, the aperture efficiency is significantly improved without sacrificing bandwidth. To validate the proposed idea, a reflector-based scalar holographic antenna is analyzed, simulated and experimentally validated. The measurement results show 3 dB gain bandwidth of 49% within 14.8–24.4 GHz and a maximum aperture efficiency of 27.5%. Moreover, the beam scanning range is 5°–61° within the 3 dB gain bandwidth. The proposed method is promising to realize a holographic antenna with wide bandwidth, high aperture efficiency, and planar integration simultaneously.