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.

A broadband low-profile high-gain folded transmitarray antenna (FTA) is proposed to generate orbital angular momentum (OAM) with circular polarization. A chiral metasurface is employed as the top layer with the function of reflecting anticipant circularly polarized (CP) incident waves while transmitting the orthogonal ones. The geometric phase is then introduced to achieve 360° coverage of the transmission phase without affecting the reflection one. To obtain a high-gain and compact planar source, a 2 × 2 patch antenna array, integrated with the bottom metallic ground, is selected as the feed. Two proof-of-concept prototypes for vortex beam generation are constructed and experimentally measured. Both simulated and measured results demonstrate that l =–1 and l =+1 OAM mode beams can be generated from 8.7 GHz to 9.5 GHz, and the measured maximum gains for l =–1 and l =+1 reach 18.1 dBi and 18.3 dBi with the corresponding peak aperture efficiencies of 6.1% and 6.4%, respectively. Meanwhile, the axial ratios (ARs) of the peak of far-field patterns are less than 3 dB over the entire operating frequency range, providing broadband CP vortex beams. The proposed high-gain low-profile broadband FTA antenna shows a promising perspective in OAM-based wireless communication.

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.

This paper presents a wideband millimeter-wave (MMW) fan-beam antenna with a flat-top, rapid cutoff radiation pattern and beam scanning capability through the use of 3-D printer technology. The proposed antenna, consisting of several periodic structure that composed of dielectric and air slabs, is fed by the WR-28 waveguide. By tunning the ratio of dielectric slab thickness to that of unit cell, the effective permittivity is controlled flexibly. The phase distribution on the aperture is carefully modulated in this way to devote high-quality flat-top patterns. Additionally, the beam can be continuously scanned within the angle range of 70° without scarifying the gain performance dramatically. For demonstration, a prototype with boresight fan-beam radiation is first fabricated and measured. The proposed antenna achieves an impedance bandwidth of 50% from 24 to 40 GHz. Measured results indicate that the wide beamwidth patterns show flat-top and sharp cutoff performance. Both E-plane and H-plane patterns draw low cross-polarization (smaller than -22 dB). Another prototype, aiming to verify the beam scanning capability, is investigated. Measured results demonstrate the performances of the proposed antennas. With such favorable electrical performance, simple structure, and low-cost fabrication, the proposed antenna is a promising candidate for 5G MMW and satellite applications.

With the increase of system complexity in wireless communications, higher requirements on miniaturization and integration are put forward for future antennas. Antennas of different frequency bands need to be placed together to achieve multiple communication goals. However, when a large-sized antenna operating at a low-band (LB) is used alongside a small-sized antenna operating at a high-band (HB), the radiation from the former can block the latter, thereby impacting the overall functioning of the antenna system. In this work, we propose a novel method for designing electromagnetic (EM) transparent antennas based on Drude metasurfaces. A dipole antenna made of Drude metasurfaces can maintain the radiation pattern of nearby HB antenna without compromising on radiation performance compared to the conventional metal-based one. An interconnected metasurface is designed to ensure low surface conductivity at HB yet high surface conductivity at LB, thus providing low radar cross section (RCS) compatible with the HB antennas. A prototype of the EM transparent dipole antenna is experimentally demonstrated and microwave measurements verify its capabilities in strong radiation and suppressing scattering at the LB and HB, respectively. Our results demonstrate an alternative way of solving EM blockages in multiband antenna systems by replacing conventional antennas with Drude-type meta-antennas.