High-Gain OAM Antenna With Low Profile Utilizing Integrated Reflective Metasurface

Orbital angular momentum (OAM) generated by metasurface has recently drawn many attentions. However, due to the hollow phenomenon in the direction of the OAM beam far-field pattern, the gain of the OAM beam decreases, which makes the sidelobe level (SLL) of the OAM beam increase. In this letter, we propose an integrated-feed OAM antenna with high gain. First, we designed a reflective metasurface working in X-band, which can generate cross-polarized EM wave, and the relationship between convergence angle of the Bessel beam carrying OAM mode and SLL is investigated. Then, a high-gain small volume antenna is designed as feeding source. Finally, the antenna is integrated with the metasurface to form the OAM antenna with the polarized plate. By applying the method proposed in this work, the gain can be maintained above 16.7 dBi within this working frequency band and the maximum gain reaches 17.6 dBi at 10 GHz, and the SLL of OAM antenna is reduced to below −16 dB in the frequency band from 9.8 to 10.3 GHz and −16.5 dB at 10 GHz.