Planar Reflectarray Antenna Research Articles

Broadband, Low-Profile, Planar Reflectarray Antenna Based on an Achromatic Metasurface

This paper presents a broadband, low-profile, and planar reflectarray antenna based on an achromatic metasurface. The achromatic metasurface has advantageous broadband focusing capabilities compared to conventional reflectarrays. Six types of unit cells offering versatile phase responses are employed to design an achromatic metasurface optimized by a convolutional algorithm. A broadband achromatic reflectarray antenna with a diameter of 270 mm is simulated, fabricated, and tested. The test results agree well with the simulated results. Notably, the 3-dB realized gain of the reflectarray antenna reaches a fractional bandwidth of 58.2% at a range of 8.9 GHz to 16.2 GHz. Furthermore, the reflectarray antenna significantly enhances the feeding antenna’s gain from 7.3 GHz to 17 GHz. The reflecting metasurface also has a low profile of 0.11 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</sub> , where λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</sub> is the wavelength in free space at 7.3 GHz. With excellent broadband performance, high gain, low profile and ease of fabrication, the developed reflectarray antenna serves as a promising device for long-distance integrated communication systems.

Design of a Wideband Flower-like Shape Metamaterial Reflectarray Antenna

In this paper, a planar reflectarray antenna is designed. The designed structure consists of new types of metamaterial unit cells. Two different flower-like shaped unit cells were studied at the center frequency of 12.5 GHz. The reflectarray contains multi cells with varying sizes of flowers. A metal plate and an air gap layer are placed behind the metamaterial sheet. A standard Ku band horn antenna feeds the structure. The F/D ratio is unity for the designed reflect array. Compared to previous reflectarray antennas, the designed reflect array consists of a limited number of cells, i.e. 121. Also, a new method without any try-and-error process is presented. The width of the designed reflector is so compact. This proposed method can be used for a reflectarray antenna with gain in the range of 20 to 30dBi with acceptable radiation efficiency. The CST software is performed to simulate and optimize the proposed structure. There is a good agreement between simulation and measurement results.

A Single-Layered Broadband Reflectarray Employing 0.15-Wavelength Elements

A single-layered broadband reflectarray antenna employing 0.15-wavelength elements is proposed and investigated in this letter. The unit cell is constituted by a ring patch inserted with an interior concave arm and arranged in a grid size of 4.5 mm × 4.5 mm, corresponding to only 0.15 wavelength at 10 GHz. Despite such a small grid spacing, a linear phase close to 360° can still be obtained by changing the height of the embedded concave arm, without adjusting the external ring size. A planar reflectarray antenna composed of 2116 unit cells is designed, manufactured, and tested. According to the measured results, the 1 dB gain bandwidth of the reflectarray antenna is 29%, while the peak aperture efficiency is 66%. Besides, satisfactory sidelobe and cross-polarization levels are also achieved. These promising features show a good overall performance of the proposed array and also successfully demonstrate the feasibility of employing 0.15-wavelength element for wideband reflectarray designs.

High‐gain side‐fed reflectarray antenna based on metasurface using sidelobe reduction optimization

This article proposes and designs a low-sidelobe planar reflectarray antenna based on particle swarm optimization (PSO). It is composed of a feed antenna and a plane reflectarray based on metasurface, and the center frequency is 5.8 GHz. The operating frequency range of the feed antenna is 5.4–6.3 GHz, and the maximum gain is 6.3 dB. The planar reflectarray based on PSO is composed of reflector elements of different sizes. The planar reflectarray antenna optimized by the PSO achieves the optimization goal of sidelobe level less than −30 dB, and the sidelobe level can be further reduced as the number of iterations increases. The antenna array adopts a side-fed feed mode to achieve a maximum gain of 22.6 dB, and 1 dB gain relative to the bandwidth accounted for 15.8%. It has great application value in scanning and multi-beam radiation for wireless communication.

Broadband Electronically Scanned Reflectarray Antenna With Liquid Crystals

In this letter, an electronically beam scanning reflectarray antenna is implemented using nematic liquid crystals (LCs). By loading a tunable phase shifter with a delay line structure in the resonance unit, the phase shift is achieved by tuning the dielectric constant of the LCs with a fixed structure through an external dc bias voltage for each unit. In doing so, dynamically controlling the reflection phase of each independent unit is realized. The experimental results show that the plane reflectarray unit can obtain a phase shift exceeding 360° with good linearity, and the maximum reflection loss is 7 dB. Moreover, a 10×10 LC-based planar reflectarray is fabricated and measured, and the bias voltage is loaded by a 100 outputs field-programmable gate array voltage module. In the frequency range of 22.1-26.1 GHz, its 3 dB relative bandwidth is 16.7%, the maximum gain of the main lobe is 20.2 dBi, and the maximum scanning angle is ±45°. The results verify the 2-D scanning functionality and the feasibility of improving the bandwidth of planar reflectarray antenna using LCs.

Gain enhancement for low cost planar reflectarray antenna using hybrid elements

By using a hybrid configuration of reflective elements of at least two different types, the gain of a planar reflectarray antenna is successfully enhanced. According to the calculated phase-shift distribution, the reflecting surface is covered mainly by traditional low-loss element such as square patches (SPs) in the first. Then the blank cells, of which the required phase-shift exceed the operational range of the SP, are covered by other elements having large phase-shift, for example, the three-ring patches. As a result, the antenna efficiency is kept in a high level because the low loss elements are in majority. Meanwhile, the main beam efficiency is kept high because the sidelobe level is suppressed by large phase-shift elements. For verification, an experimental array is fabricated on an inversely suspended, low cost FR4 substrate. The simulated result shows that the sample antenna is advanced in high gain and low sidelobe level, comparing with its traditional counterparts with only one type reflectarray elements. The measured result agrees well with the simulations, which show the gain of the antenna is higher than 26 dB, while the sidelobe suppression is lower than −19 dB. The aperture efficiency reaches about 47.04% at 14.0 GHz, which achieves the performance of high-cost reflectarray antenna.

RCS reduction of reflectarray using new variable size FSS method

This study focuses on the reduction of the Radar Cross Section (RCS) for planar reflectarray antenna by using Frequency Selective Surface layers. For this study, a novel broadband reflectarray antenna is designed. The designed reflectarray antenna is composed of a broken circular ring and a cogwheel geometry. With variable size geometry, the proposed unit cell has more than 400° phase range which provides a broader bandwidth of the antenna. The RCS reduction of the reflectarray antenna is provided using variable size elements of the FSS technique and modification of reflectarray antenna ground plane. Therefore, the backscattering RCS of FSS backed modified reflectarray antenna is reduced up to 10 dB in the whole frequency band. This RCS reduction cost a reduction in terms of antenna gain level. The scattering characteristics, radiation patterns and RCS of both metallic grounded and FSS backed antennas are simulated and experimentally verified.

Design and characterization of millimeter wave planar reflectarray antenna for 5G communication systems

This work provides design and characterization of millimeter wave reflectarray antenna based on unit cells as well as periodic reflectarray design at 26 GHz. Diverse unit cell design configurations have been investigated based on simulations and scattering parameter measurements for feasibility of designing an optimum performance 5G reflectarray antenna. It has been demonstrated that the rectangular patch element provided minimum reflection loss of 1.02 dB and maximum bandwidth of 560 MHz. However, the phase error for rectangular patch element was observed to be 80°, which is much higher as compared to 10° and 13° in the case of rectangular ring and circular ring elements respectively. Periodic reflectarray antennas were also designed with main beam focused at 40° in the azimuth plane achieved with tilted array instead of using an offset feed. Radiation pattern measurements were carried out for further characterization where a maximum gain of 26.7 dB was provided by reflectarray designed with circular ring elements with variable radius. On the other hand, rectangular patch element array provided higher 1 dB gain drop bandwidth of 13.6% as compared to circular ring element reflectarray, which demonstrated a bandwidth of 13.1%. However, side lobe levels were observed to be higher at −18.4° for rectangular patch element reflectarray as compared to −19.4° in the case of circular ring elements based reflectarray antenna.

Low-RCS Reflectarray Antenna Based on Frequency Selective Rasorber

We design a low-radar-cross-section (RCS) planar reflectarray antenna by using a frequency selective rasorber (FSR). Due to the metal-backed configuration and focusing effect of the phase modulation surface, the RCS of a planar reflectarray antenna is generally quite high. Besides, an out-of-band signal focused by the reflector may cause serious interference to the system and affect the performance of facilities. To reduce the RCS of the reflectarray and suppress out-of-band interference, the FSR with a transmission window is designed and covered in front of the reflectarray. Simulation results show that the out-of-band RCS of the reflectarray is significantly reduced without affecting the radiation performance. To verify the benefits of the structure in antenna's RCS reduction (RCSR) and interference suppression, the reflectarray, the FSR, and the horn antenna work at 8.9 GHz are designed, fabricated, and measured. Measurement results show that the gain of the proposed low-RCS reflectarray antenna has only 0.3 dB decrease compared with the gain of non-FSR configuration. Meanwhile, the RCS of the proposed structure is remarkably reduced, and the –10 dB RCSR is obtained from 4 to 12.5 GHz.

Design of beam scanning metamaterial antenna

A beam scanning metamaterial planar reflective array antenna is designed by combining square and octagonal rings. Compared with the traditional array antenna design, this array antenna adopts a new phase compensation method thus by combining the phase curve obtained by the reflective array unit when the material of the dielectric substrate is different, the phase compensation from 0~360 is realized, so that the phase curve of the array unit need not to completely cover 0~360, and Hermite interpolation way is used to make up for the poor linearity of the phase characteristics. The advantage of this method is its universality, which reduces the design requirements for the array unit. Using this method, several single-layer plane reflectarray antennas were designed. The simulation results show that the direction of the reflected beam is consistent with the expected setting, and the side lobe and the main lobe are at least 15 dB apart. By adjusting the range of the solid-state plasma excitation region of the metamaterial to change the resonance structure of the array unit, beam scanning in different spatial frequencies is achieved, which provides a new method for the design of the planar reflectarray antenna.

A novel broadband reflectarray antenna with lattice stubs on square element for Ku‐band application

ABSTRACTIn this article, a single layer unit cell reflectarray antenna comprising a fixed square patch to which is attached a lattice of symmetric open ended stubs is proposed. The phase response of the proposed unit cell element is governed by the length of the lattice, providing more than 600° of reflection phase variation. The unit cell element of 0.54λ0 × 0.54λ0, has a thin dielectric substrate thickness of 0.036λ0 and is placed above an air layer making the overall unit cell thickness of 0.126λ0. A 15 × 15 elements Ku‐band reflectarray antenna is designed with an area of 18 × 18 cm2. The reflectarray is center fed by a linearly polarized pyramidal horn antenna. The planar reflectarray antenna is fabricated and has wide −1 dB gain bandwidth, about 20% covering 12.1–14.8 GHz. The measured antenna gain at 13.5 GHz is 25 dB which is equivalent to 39% efficiency. The proposed unit cell and the reflectarray antenna are simulated through CST and HFSS software packages. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:2699–2702, 2015

DIELECTRIC RESONATOR ANTENNA REFLECTARRAYS MOUNTED ON OR EMBEDDED IN CONFORMAL SURFACES

Abstract—In this paper, reflectarrays mounted on or embedded in cylindrical and spherical surfaces are designed, analyzed, and simulated at 11.5GHz for satellite applications. A unit cell consists of a square dielectric resonator antenna (DRA) mounted on or embedded in metallic conformal ground plane is investigated. The radiation characteristics of the designed reflectarrays are investigated and compared with that of planar reflectarray. A 13×13 planar reflectarray antenna on the x-y plane was designed. By varying the length of the DRA element between 2 mm and 6.2 mm a full range from 0◦ to 360◦ phase shift can be obtained. The size of each element is equivalent to a compensation phase shift. A maximum directivity of 24.3 dB was achieved while the side lobes were below −12.94 dB in E-plane and −15.79 dB in the H-plane for planar reflectarray. A Full-wave analysis using the finite integration technique (FIT) is applied. The results are validated by comparing with that calculated by transmission line method (TLM).

Modeling a Low-profile Reflect Array Antenna

The theoretical analysis of a planar reflect-array antenna consisting of a rectangular microstrip patch radiators is presented. Such an antenna is to be designed to convert spherical wave radiated by feed horn antenna into plane wave by phasing of reflected wave due to adjusting the patch sizes and arranging them by principle of Fresnel mirror. The modelling of array antenna is based on the modelling of elementary equivalent waveguide cell consisting patch radiator at the interface between superstrate and grounded substrate layers. Spectral Domain Approach (SDA) of Method of Moments is used to analyse the characteristics of elementary waveguide cell. Theoretical and experimental results are compared.

A C/Ka Dual Frequency Dual Layer Circularly Polarized Reflectarray Antenna With Microstrip Ring Elements

This paper reports a dual frequency dual layer circularly polarized reflectarray operating in the C and Ka bands. A 0.5-m right-hand circularly polarized planar reflectarray antenna is designed using microstrip ring elements of variable rotations to achieve a cophasal beam at broadside. The microstrip ring elements are more compact than the traditional reflectarray elements and can minimize blockage for the multilayer multifrequency applications. The highest efficiencies measured are 46% at 7.3 GHz and 38% at 31.75 GHz. The tested cross-polarization levels are -21 dB at 7.3 GHz and -29.2 dB at 31.75 GHz at the broadside direction. The tested results show that the designed ring element is suitable for both the single and dual layer applications with good bandwidth and circularly polarized performance.