Ultra-Wideband Reconfigurable X-Band and Ku-Band Metasurface Beam-Steerable Reflector for Satellite Communications

A continuously reconfigurable metasurface reflector based on unit cell mushroom geometry that was integrated with a varactor diode is presented in this paper. The unit cell of the metasurface was designed and optimized to operate in the X-band and Ku-band, improving satellite communication’s quality of service. The losses mechanisms of continuous control over the unit cell phase reflection in beam steering resolution are considered and the analysis results are presented. The unit cell design parameters were analyzed with an emphasis on losses and dynamic reflection phase range. The unit cell magnitude and phase reflection are shown in the wide frequency bandwidth and showed a good agreement between all the measurements and the simulations. This metasurface enabled a high dynamic range in the unit cell resonant frequency range from 7.8 to 15 GHz. In addition, the reflection phase and absorption calibration are demonstrated for multiple operating frequencies, namely, 11 GHz, 12 GHz, and 13.5 GHz. Furthermore, design trade-offs and manufacturing limitations were considered. Finally, a beam-steering simulation using the designed metasurface is shown and discussed.

A HIGH GAIN AND HIGH BANDWIDTH REFLECTARRAY ANTENNA FOR 5G COMMUNICATION

This paper presents the design of high gain and bandwidth reflectarray for 5G networks operating in Millimeter-wave (mmWave) at 28GHz and 38GHz. A polymer benzocylobutene (BCB) is used as substrate material having a dielectric constant of 2.65, and low tan δ ≤ 0.0008. The unit cell is optimized to achieve full phase reflection of 334o over the operating band. Enhanced gain, wider bandwidth and full phase reflection are achieved by making air holes in the substrate. A 15×15 elements reflectarray based on the optimized unit cell is designed to enhance the gain. The reflectarray is excited through horn feed having a gain of 15dB with a feeding distance of 165mm and 00 offsets. A gain of 23dB was observed at lower operating frequency (i.e 28GHz) and 25dB at upper operating frequency (i.e 38GHz)with a bandwidth of 2GHz at both operating frequencies.

Dynamic Control of Ultrathin Electromagnetic Absorber Using Active High Impedance Metasurfaces

In recent years, active metasurfaces have induced more interests, which provides great freedom of wave manipulation and gives rise to many novel phenomena. High impedance metasurfaces are a kind of artificial structures characterized by the in-phase reflection at the resonant frequency. It works as a magnetic mirror and can be applied in subwavelength cavity, low profile reflector antenna, etc. When introduce in tunable components, it possesses versatile functionalities and broader application. In this paper, we proposed an active high impedance metasurface which exhibits highly efficient absorption to the electromagnetic incidence. As an array of diodes are loaded between the gap of periodic gratings and applied with positive bias, the absorption frequency can be dynamically controlled by the level of bias voltage. At the resonant frequency, the reflection from the metasurface can be less than 1%, implying that most of the incidence is absorbed by the magnetic resonance of high impedance metasurface. When the bias voltage is tuned from 0 to +1.33 V (the forward voltage), the resonant peak rises from 8.5 to 9.1 GHz, providing a flexible control of electromagnetic wave absorption in X band.

Влияние поляризации считывающей волны и циркулярного дихроизма на дифракционную эффективность отражательной голограммы в кубическом оптически активном фоторефрактивном поглощающем пьезокристалле

In the approximation of slowly varying amplitudes, a system of coupled waves equations is obtained, which is applicable for describing the diffraction and coupling of elliptically polarized light waves on a volume phase-amplitude holographic grating formed in a cubic optically active photorefractive absorbing piezoelectric crystal. The dependence of the diffraction efficiency of the phase reflection hologram on the ellipticity of the readout wave and the thickness of the Bi12SiO20 crystal of the (001) and (111) cuts was studied. The regularities of the effect of circular dichroism on the diffraction efficiency of the phase reflection hologram are analyzed. It is shown that for crystal of (001)-cut the maximum diffraction efficiency of the reflection hologram depending on the crystal thickness can be achieved using a readout wave both with linear polarization and with elliptical polarization. For crystal of (111)-cut the highest diffraction efficiency is achieved using a linearly polarized readout wave. It has been established that the effect of circular dichroism on the intensity of the reconstructed wave depends on the cut of the crystal, the ellipticity of the readout wave and the thickness of the crystal.

A Square Patch with L and Inverted L shaped slotted AMC structure for Wi-Fi Applications

To improve the antenna characteristics in terms of bandwidth, gain and its radiation characteristics without providing any phase reflections, Artificial Magnetic Conductor (AMC) are used in antenna designing. This paper initially designed AMC structure for 2.4GHz frequency. The proposed AMC structure consists of three L shaped and inverted L shaped slots and provides zero degrees phase reflection at 2.4GHz resonant frequency. This proposed AMC structure is incorporated on conventional micro strip square patch antenna and results are simulated in High Frequency Structure Simulator (HFSS) software. The Proposed AMC incorporated patch antenna, return loss is improved from -16.16dB to -31.75dB, VSWR is from 1.42 to 1.05, the band width is increased from 16.5 MHz to 348.1 MHz This design resonates at a frequency of 2.4GHz and applicable to Wi-Fi applications.

Multiband Printed Koch Antenna Unified with Hilbert Split-Ring Structure for Better Front-to-Back Ratio

A multiband printed Koch antenna integrated with multi-band high-impedance surface (HIS) is proposed. The antenna can operate at three frequencies like 11.725 GHz, 26.155 GHz and 39.22 GHz which covers application in frequency bands namely X-band (8-12 GHz), K-band (18-27 GHz), and Ka-band (26.5-40 GHz). In order to achieve a modest design with better front-to-back ratio (FBR), gain, directivity and radiation efficiency a multi-band Hilbert split-ring HIS is presented as a reflector. The proposed HIS has an array of slotted square patches based on Hilbert curve. This arrangement provides in-phase reflection at the operating frequencies and can be presented as an artificial magnetic conductor (AMC). The antenna when integrated with HIS has an incorporated uniform profile thickness of 2 mm for different frequencies of operation. The printed Koch antenna is simulated, analyzed for various substrate thickness and is finally integrated with Hilbert split-ring HIS to obtain good FBR and radiation efficiency in all the three bands.

Design of a Low Scattering Metasurface for Stealth Applications

The design of a metasurface with low radar cross section (RCS) property is presented in this paper. The low scattering of the metasurface is achieved by applying the artificial magnetic conductor (AMC) unit cells in three different configurations. Two different AMC unit cells with an effective phase difference of 180 ± 37° are first designed to analyze the out of phase reflection in a wideband frequency range from 5.9 to 12.2 GHz. Then, the unit cells are placed in a chessboard-like configuration, newly constructed rotated rectangular-shaped configuration, and optimized configuration to study and compare the RCS reduction performance. All designs of the metasurface with different configurations show obvious RCS reduction as compared with the metallic plate of the same size. However, the relative bandwidth of the optimized metasurface is larger than the chessboard-like configuration and rotated rectangular-shaped configuration. To certify the results of the simulations, the metasurface with the optimized configuration is fabricated further to measure the RCS reduction bandwidth. The measured results are in good accordance with the simulated results. Therefore, the proposed metasurface can be a good option for applications where low RCS is desirable.