A wide-angle frequency-controlled beam scanning antenna fed by the standing wave of spoof surface plasmon polaritons (SPPs) is proposed. The antenna is constructed by placing two rows of circular patches at both sides of an SPP waveguide. The waveguide is composed of two ultrathin corrugated metal strips with two levels of depth, which generate two cut-off frequencies. In the working band between two cut-off frequencies, circular patches are fed by standing waves. Simulated and measured results validate that the proposed antenna has a much wider scanning angle of 83° from 9.2 to 16 GHz than that in published results. The measured gains of the proposed antenna are greater than 10.3 dBi over the whole band. The proposed beam-scanning antenna has advantages in radar and wireless communication system because of its low cost, compact structure, and wide beam-steering.

In this paper, we propose an approach to generate and transform surface wave to orbital angular momentum (OAM) vortex wave using flat dispersive metasurface. The metasurface cell is a ring-surrounded bowtie patch which is specifically designed for controlling the phase of the scattered fields. The phase response of every metasurface cell is optimized to meet the phase compensation required for generating OAM wave. The metasurface array operating at 10 GHz for generating multiple OAM modes of $\ell=0,1$ and 2, respectively, are designed and fabricated. The simulated and experimental results demonstrate that different OAM modes can be generated. The near field and far field features of these arrays are measured, and the transmitting and receiving tests show that different OAM modes are isolated so that they can be used for channel multiplexing.

A deep-learning enabled discrete dielectric lens (DDL) antenna with terahertz hologram reconfigurability is proposed. The antenna is constructed by two cascaded discrete dielectric lenses, which are designed based on a diffractive deep neural network (D ² NN) with an improved loss function, fed by a static horn. The DDL antenna can achieve dynamic holographic imaging by a simple mechanical translation of the perfect electric conductor (PEC) mask attached to the first lens instead of locally controlling individual meta-atoms through incorporating active elements or phase change materials with complicated feeding networks. The phase profiles for the DDL antenna design are obtained by training four customized input field patterns and corresponding anticipated output target images with the modified D ² NN. Dynamic switching of four number images “1, 2, 3, 4” is demonstrated by both full-wave simulated and experimental results. The proposed DDL antenna and design strategy present a new approach to achieve wavefront reconfiguration, especially in the absence of tunable components at high frequencies.

An approach to producing the orbital angular momentum (OAM) based on spoof localized surface plasmons (spoof LSPs) in microwave frequencies is demonstrated both theoretically and experimentally. The fundamental and high-order modes of spoof LSPs occur when a textured metallic surface is excited with a microstrip line. Two orthogonal modes of spoof LSPs with $+90°$ or $-90°$ phase retardation are superimposed, resulting in a OAM-vortex mode. In the proposed design, two separate feeding ports are employed to excite the orthogonal resonant modes simultaneously, and a hybrid coupler is used to provide the required $\pm 90°$ phase retardation. By loading a circularly arranged dipole array on the spoof LSPs, the confined surface waves of the spoof LSPs can be converted into radiated vortex waves. To verify this idea, an OAM-mode emitter with indices of $\pm 3$ is fabricated and measured. Experimental near-field distributions and far-field radiation patterns show excellent agreement with the simulated results.

A unidirectional beam-scanning antenna is proposed. The antenna is constructed by placing a series of circular radiating elements on a 2-mm dielectric slab backed by a corrugated metal-insulator-metal (CMIM) ground. The CMIM structure is introduced not only as a ground but also as a waveguide for spoof surface plasmon polaritons (SSPPs). The beam-scanning function is realized through the phase difference of SSPPs fed to the radiating elements. In addition, the CMIM ground reflects downward radiation waves onto upward space, leading to a unidirectional pattern and enhanced radiation gain. Both the numerical simulation and experiment results demonstrate the good performance of the proposed antenna. They validate that the antenna achieves unidirectional radiation and scanning angle of 57° when the frequency varies from 6.2 to 9 GHz with the frequency sensitivity of 20.4°/GHz. The realized gains are higher than 8.11 dBi over the entire band. Compared with the published works, this paper provides a novel feed technology, a simpler structure, and higher frequency sensitivity. The high-frequency sensitivity is beneficial to reduce the bandwidth burden of the entire system. The antenna has potential applications in satellite communication.

Metasurface antennas (MAs) have been proposed as innovative alternatives to conventional bulky configurations for satellite applications because of their low profile, low cost, and high gain. The general method of surface impedance modulation for designing MAs is complicated, and achieving broad operation bandwidth remains a challenge because of its high dispersion response. We propose a novel and easy technique to control cylindrical surface waves radiated by a phase-tuning metasurface. Simultaneously, this technique exhibits a considerably wide working bandwidth. A detailed analysis of the radiation mechanism is discussed. A left-hand circularly polarized (LHCP) antenna and a right-hand circularly polarized (RHCP) antenna that are based on the phase-tuning metasurface are simulated and measured. The measured fractional 3-dB gain bandwidth and gain are higher than 17% and 15.57 dBi, respectively, which are consistent with the simulated results. Moreover, 30% 3-dB axial ratio is achieved for the LHCP and RHCP antennas. To the best knowledge of the authors, it is for the first time to realize a circularly polarized broadband MA by using the phase-tuning mechanism. The approach can be regarded as a new starting point for antenna design, thereby paving the way for the development of broadband and low-profile antennas for future satellite communication.