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Metasurfaces have gained a considerable amount of interest in the past decade for their capabilities to manipulate electromagnetic (EM) waves in different manners. They have offered multiple functionalities in terms of wave control depending on the given application. In terms of wave control, particularly EM beam splitting, it can be challenging compared to the given literature review, to achieve a wide number of beam-splitting reflections and coverage for multiple incident angles simultaneously. In this paper, we focus on the design of a metasurface based on the methodology of high periodicity supercell design (5.76 λ) and impedance modulation to achieve a various number of beam-splitting angles, while maintaining the same coverage at multiple incident angles for millimeter-wave (mm-Wave) frequencies. Following the generalized phase law of reflection alongside proper optimization of the surface impedance, the proposed reflective anomalous beam splitter (RABS) metasurface is designed to be polarization independent, and high reflection efficiency is achieved with a wave beam split into 11 different directions while operating for multiple incident angles simultaneously, making it a promising candidate to overcome challenges for various mm-Wave communication applications, especially in expanding 5G coverage in non-line of sight regions at a 28 GHz frequency band. The performance of the RABS metasurface is evaluated using both full-wave simulations and experimental measurements, which demonstrate its effectiveness in achieving 11 efficient reflective anomalous beams with a reflection efficiency of up to 96.65% and 97.36% in TE and TM modes at 28 GHz. [ABSTRACT FROM AUTHOR]

Electromagnetic (EM) RF (radio frequency) energy harvesting in dynamic ambient environments is a challenge for conventional energy harvesting systems such as rectennas. The main challenges are the low efficiency of the collector and low ambient power levels, which makes it hard to consider in industrial applications. Several research works have focused on the design of high-efficiency antennas to achieve an efficient and maximum possible level of RF EM energy harvesting. Their main objective is to improve the EM energy harvesting system by overcoming the low efficiency of the collector, which is the main part of the rectenna system. In this work, we propose and investigate a methodology in terms of EM energy harvesting based on the concentration and focusing of EM energy in a small zone where it can be easily collected and transferred indirectly to the rectenna system. It consists of a focusing device and a methodology to associate the latter with existing RF energy harvesting systems. We demonstrate a focusing metasurface design implemented alongside an off-the-shelf rectenna device at 900 MHz, where an enhanced energy harvested power level up to a linear gain of 8 is achieved compared to the case when only the rectenna is used. Numerical results as well as measurements results in an anechoic chamber are shown. Experimental power received levels are given both in the focusing plane and in time for the validation of the concept. [ABSTRACT FROM AUTHOR]

In this paper, a cascaded retrodirective metasurface is designed and demonstrated to operate simultaneously at a wide range of incident angles from − 30 ° to − 10 ° and 10 ° to 30 °. It is based on the design of several retrodirective super-cells following the generalized Snell's law of reflection, where each super-cell is designed to redirect an incoming wave back in the same direction with high efficiency. This metasurface is a very good candidate as a retroreflector for radar cross-section (RCS) enhancement of targets with poor backscattering. Retrodirective topologies have been a subject of interest, and several engineered topologies exist, such as the corner dihedral. Despite their good performances at a range of incident angles, their 3-dimensional bulky structure makes them hard to implement for different applications and they do not address extreme incident angles. The metasurface proposed can be a complementary solution to existing topologies for addressing extreme oblique incident angles while being more compact due to its two-dimensional subwavelength structure design. The monostatic radar cross-section (RCS) performance of the designed metasurface of dimensions 8.163 × 56.23 cm 2 has been compared to that of a conventional corner dihedral of dimensions 8 × 15.5 × 7.75 cm 3 , and a gain of up to 50 dB of monostatic radar cross section (RCS) in the ranges − 30 ° to − 20 ° and 20 ° to 30 ° was obtained. Comparable performances are observed in the ranges − 20 ° to − 10 ° and 10 ° to 20 ° between the designed metasurface and the corner dihedral. Experimental results are shown to be in good agreement with simulation results. [ABSTRACT FROM AUTHOR]

A novel compact coplanar waveguide (CPW)-fed planar monopole antenna with triple-band operation is presented for simultaneously satisfying the LTE 2600, WiMAX, WLAN and X-band applications. It is printed on a single-layered FR4 substrate. In this paper, the proposed antenna, which occupies a small volume of 3 0 × 2 8 × 0. 8 mm3 including the ground plane, is simply composed of a CPW-fed monopole with U-, L- and T-shaped slots. By carefully selecting the lengths and positions of both L-shaped and U-shaped slots, a good dual notched band characteristic at center-rejected frequencies of 3.10 GHz and 4.50 GHz can be achieved, respectively. The T-shaped slot is etched on the radiating element to excite a resonant frequency in the 7 GHz band. Then, to prove the validation of the typical design, a prototype model is fabricated and measured. The experimental result shows that the three frequency bands of 2.31–2.80 GHz (490 MHz), 3.37–3.84 GHz (470 MHz) and 5.04–7.94 GHz (2900 MHz) can successfully cover the desired bandwidths of LTE2600/WiMAX (3.50/5.50 GHz)/WLAN (5.20/5.80 GHz) and the X-band communication systems (7.1-GHz operation). The principal applications of the X-band are radar, aircraft, spacecraft and mobile or satellite communication system. Nearly omnidirectional and bidirectional radiation patterns of the triband antenna are observed in both H- and E-planes, respectively. In addition, a reasonable gain over the operating bands has been obtained. Indeed, the good agreements between simulation and measurement results have validated the proposed structure, confirming its potential for multiband wireless communication services. [ABSTRACT FROM AUTHOR]