In this letter, a wide-beam (at two main planes) antenna is proposed. To broaden the 3-dB beam-width of the original antenna, a pair of parasitic patches with metallic vias is creatively arranged on either side of the original radiation patches. Based on the proposed antenna element, two linear phased arrays are fabricated and measured. Measured results reveal that the wide-angle scanning capability of both H-plane and E-plane arrays can be obtained. The scanning beam of the former can cover territories ranging from -90 to 90, with gain loss within 3dB (8GHz-11GHz). The scanning beam of the latter can cover territories ranging from -70 to 70, with gain loss of 3-5dB (8GHz-10GHz).

A novel integration strategy of microstrip antenna and metasurface is proposed to achieve low-radar cross section (RCS) and improved radiation performance simultaneously. Aimed at the applications in stealth cylindrical carrier, the antenna has a circular configuration, and the metasurface cells are closely arranged around the radiation patch in a concentric ring-type manner. Moreover, the mode analysis method is fully used to analyze the antenna's working mechanism and guide the optimization process. Owing to the addition of metallic vias, the original quasi-TM ₃₀ mode is altered to three series-TM ₁₀ modes and thus enhanced gain is achieved. Interestingly, the addition of vias also generates a new resonance which widen the antenna's impedance bandwidth. In another aspect, both in-band and out-of-band RCS reductions are obtained simultaneously. Finally, two prototypes are fabricated to validate the proposed design strategy. Good agreements between measurements and simulations are obtained. Measured results show that the gain of the proposed antenna is at least 3 dB higher than the conventional antenna in the entire operating band, and obvious RCS reduction is achieved from 4.0 to 8.5 GHz concurrently.

Radar cross section (RCS) reduction in the working band of antennas, likely leading to radiation performance change or deterioration, is quite difficult for both antenna elements and arrays. Aimed at this problem, this paper presents a novel design strategy of microstrip patch antennas with low in-band RCS. This strategy combines metasurface with antenna from the perspectives of both structure and electrical performance. To be specific, anisotropic metasurface is proposed to replace the conventional patch and behave as the radiating structure of the antenna directly, which does not increase the original antenna size. Through proper connection of the metasurface units, the novel antenna has the same radiation performance with conventional microstrip antenna but low in-band RCS for any polarized incidence. The radiation and scattering mechanism of the novel antenna is carefully elaborated, from which a frequency reconfigurable antenna is also derived by loading varactors. Furthermore, the different design strategies of low in-band-RCS antenna element and array are clarified. On the basis of which, a 4×4 array is developed to achieve in-band RCS reduction with radiation performance kept. Both numerical and experimental results are demonstrated and the reasonably good agreements verify the effectiveness of the proposed strategy.

In the conventional routes to obtain stealth array antennas, various techniques are used to reduce the radar cross sections (RCS) of existing antennas based on experience-relying trial-and-error and time-consuming optimizations. To address the issue, we propose a reverse thinking, i.e., low scattering performance precedes radiation performance, and present a universal and definite route to achieve low-RCS array antennas directly from metasurfaces rather than from antennas. A specific design method is carefully elaborated to illustrate this route. Firstly, a low RCS metasurface is designed. Then an interdigital arrangement of the metasurface and proper feeding techniques are exploited to excite parts of the metasurface cells to produce efficient radiations. These partially excited cells play twofold roles as the radiating structures for array antenna and as part of scattering structures for low-RCS property. As examples, one- and two-dimensional metasurface-based array antennas are elaborately designed and fabricated, in which good radiation performance and broadband low RCSs are achieved simultaneously. Both numerical simulations and experimental results verify the effectiveness of the proposed method. It suggests that the proposed route is more likely to speed up the design process and yield an integration structure and controllable performance.

An ultrawide-angle frequency beam scanning leaky-wave antenna (LWA) with a high scanning rate based on spoof surface plasmon polaritons (SSPPs) waveguide is proposed in this communication. A row of elliptical patches is placed periodically near the SSPPs waveguide, which can shift the fundamental mode of SSPPs waveguide to the fast-wave region and radiate electromagnetic (EM) waves. The simulated results show that the proposed LWA achieves an ultrawide scanning angle range of 172° over a narrow operation bandwidth of 9.8–12.28 GHz, which implies a high scanning rate. The simulated average gain of the proposed LWA is 10.13 dBi and its average total efficiency is 75.35%. The proposed LWA is fabricated and measured. The measured scanning angle range is 167° in the frequency band of 9.9–12.25 GHz, and the measured average gain is 9.73 dBi. Good agreements between the simulated and measured results are obtained, validating the proposed design.

Metasurfaces trigger great interests due to their potential ability to manipulate the propagation of electromagnetic (EM) waves. Plenty of fascinating EM phenomena have been generated using metasurface. However, two defects are hindering their development. The first one is that most metasurfaces only perform a specific functionality once designed, which means they do not possess tunable properties. The second defect is that most of them work either in reflection mode or transmission mode, leaving half of the EM space completely unexplored. Therefore, it is challenging to design metasurface with tunability and entire-space working modes simultaneously. Here, a tunable metasuface is presented to solve these problems. The proposed metasurface element is a multilayer structure which can manipulate EM waves in the entire-space. Concurrently, PIN switches are loaded on each element which can dynamically control transmission and reflection phases. Thus some intriguing EM modulation functions in the entire-space are realized, such as beam forming, anomalous reflection and diffusion. Simulated and experimental results prove the tunable metasurface. The proposed metasurface offers a feasible strategy to design tunable metadevices and for other related practical applications.