Reflectarray Antenna Research Articles

Wideband millimeter-wave reflectarray antenna with reduced cross-polarization

Abstract A novel wideband reflectarray antenna (RA) is designed for 5G millimeter (mm) wave communications in the frequency range of 26.5–36 GHz. The proposed unit cell is constructed using a grid periodicity of 0.52 ${{\lambda }_0}{ }$ that offers 636° phase change through phase delay lines (PDLs) ( ${{\theta }_{\text{s}}}$ ). These PDLs are attached to the outer end of the unit cell comprising semi-circular rings. Bandwidth enhancement is achieved by incorporating a corrugated slot technique and a suitable air gap beneath the substrate. The proposed center-fed reflectarray is composed of 513 elements distributed in a circular aperture (13.46 ${{\lambda }_0}$ ). Using mirror-symmetrical distribution of the unit cells, a cross-polarization reduction as low as −50 dB is realized. At 30 GHz, RA has a measured peak gain of 28.2 dBi, a sidelobe level of −14.3 dB, and an aperture efficiency of 31.4%. The prototype antenna is fabricated, and the simulation results are experimentally validated. The measured 1-dB and 3-dB gain bandwidths of the proposed reflectarray antenna are 31.3% and 41.6%, respectively. The proposed broadband reflectarray can be a potential choice for inter-satellite services like inter-satellite networking/satellite positioning and control; fixed satellite services such as GPS satellite synchronization and data direct to home TV; and satellite position fixing.

High-power Broadband Reflectarray Antenna with Height Adjustment

To enhance the power capacity and bandwidth of antenna arrays, a high-power broadband reflectarray antenna with height adjustment has been proposed. The high-power reflectarray comprises reflective elements, a beam scanning control system, and a high-power feed source. In the design, the high-power feed source horn radiates GW-level high-power microwave radiation onto the reflective elements, which adjust their relative height through the beam scanning control system to compensate for phase shifts, enabling the beam to be steered in any direction. The reflective elements utilize a novel total internal reflection form, offering a simple structure that ensures the power capacity and aperture efficiency, as well as bandwidth of the antenna array. Full-wave simulation results demonstrate that this phased array can achieve a 360° phase shift, two-dimensional ±50° beam scanning, an aperture efficiency of 81%, a -1dB bandwidth of 10.8%, and a power capacity of 14GW.

Compact Dual-Circularly Polarized Reflectarray Antenna Using Semicircle Strips Elements With Independent Focus and Beam Directions

Compact Dual-Circularly Polarized Reflectarray Antenna Using Semicircle Strips Elements With Independent Focus and Beam Directions

A High Aperture Efficiency 1-bit Reconfigurable Reflectarray Antenna With Extremely Low Power Consumption

A High Aperture Efficiency 1-bit Reconfigurable Reflectarray Antenna With Extremely Low Power Consumption

Modern Reflectarray Antennas: A Review of the Design, State-of-the-Art, and Research Challenges

Modern Reflectarray Antennas: A Review of the Design, State-of-the-Art, and Research Challenges

Composite anisogrid lattice toroidal shell: Application to a load-carrying rim of the spacecraft reflectarray antenna

A novel design of the composite transformable/foldable rim of the spacecraft reflectarray antenna is presented in the paper. The rim is made in the form of anisogrid lattice toroidal shell split into six parts that are jointed using hinges containing helical springs. The springs create the moments required to deploy the antenna in orbit. A dielectric flexible flat membrane with reflective radiating elements generating a radio signal with required directivity is stretched on the rim. An algorithm of the finite-element model generation is developed for the toroidal rim using a typical finite-element unit cell of lattice structure. The lattice toroidal shell is modelled as a three-dimensional frame composed of curvilinear ribs. The results of design analysis of the lattice rim delivering a minimal mass to its structure subject to constraints imposed on the fundamental frequency, values of stress, and the buckling load factor are presented in this work. The corresponding set of design parameters of lattice structure, including the angle of orientation of helical ribs, number of helical ribs of one orientation, and size of the ribs’ cross section are identified based on these results.

Transmission–Reflection‐Integrated Metasurface with Simultaneous Amplitude and Phase Controls of Circularly Polarized Waves in Full Space

AbstractIn recent years, manipulations of amplitudes and phases of circularly polarized (CP) waves using metasurfaces have attracted significant attention. However, most of the current works are limited to operating in reflection or transmission space, and the amplitude manipulations are mainly achieved through polarization conversion or resistive loss, which will inevitably lead to cross‐polarization pollution and energy waste. Here, a transmission–reflection‐integrated metasurface that can manipulate the amplitudes and phases of the CP waves simultaneously in full space, which can not only realize arbitrary amplitude allocation of transmitted and reflected CP waves but also independently manipulate their phase responses is proposed. As proofs of concept, two integrated metasurfaces are designed and demonstrated, including a CP reflectarray antenna with simultaneously low side‐lobe level and low cross‐polarization level, and a meta‐grating that can arbitrarily control the intensity of transmitted diffraction wave while focusing the reflected wave. Both simulated and measured results agree very well with the theoretical predictions, demonstrating the powerful ability of the proposed metasurface to control the CP waves in full space, which is promising to be applied in future satellite communications, photonic meta‐devices, and so on.

Multibeam digital metasurface reflectarray antenna for 5G millimeter wave applications

AbstractA phase‐graded multibeam high gain digital metasurface reflector array (DMSRA) antenna for 5G millimeter wave communication is proposed in this letter. The DMSRA unit‐cell element is composed of a dipole loaded with endstubs. The variation of load across the diploe manipulates the reflection phase response of the incoming electromagnetic wave. A discretized phase state of 0° and 180° is obtained for an optimized loaded dipole. The phase states mimic the binary meta bit‐0 and meta bit‐1. The metabits are distributed along the reflecting surface using a digital coding sequence to form multiple beams in the desired direction. A coding sequence of 010101… is employed to design a two‐dimensional phase‐graded metasurface to generate a four‐beam radiation pattern. The designed digital metasurface reflectarray antenna of dimensions is fabricated and measured to validate the performance. The DMSRA is excited by an antipodal Vivaldi antenna positioned at an optimized focal point of 28 mm. The measured results show a four‐beam radiation pattern obtained over the frequency range of 27.5–28.5 GHz along azimuthal and elevation planes, with a peak beam gain of 10.5 dBi at 28 GHz.

Three‐dimensional metal‐only phoenix cell and its application for reflectarrays

AbstractA 3D metal‐only waveguide‐based phoenix cell for reflectarray is presented. The proposed cell consists of two concentric square waveguides and a metallic block in the centre, which offers two operation modes. The first mode uses its cross section to tune reflection phase while the second mode varies the heights of two waveguides to manipulate reflection phase. The principle of the two different modes is analysed in detail. A metal‐only reflectarray antenna at 20 GHz is designed based on the first mode of the phoenix cell. It is fabricated using selective laser melting 3D printing technology. A good agreement between simulations and measurements is achieved. The measured gain at 19.75 GHz is 30.25 dBi with an aperture efficiency of 51.17% respectively. Also, the measured 1‐dB gain bandwidth is 15% (19–22 GHz). A dual band metal‐only reflectarray operating at 20 and 25 GHz is designed based on the second mode of the phoenix cell. The two metal‐only reflectarray antennas fully demonstrate the capabilities of the proposed 3D metal‐only phoenix cell.

Antena Tatasusun Pantulan Boleh Konfigurasi Semula: Latar Belakang, Klasifikasi dan Mekanisme Boleh Konfigurasi

Reflectarray antennas have emerged as one of the most suitable choice for 5G network base station antennas due to their ability to combine the advantages of parabolic reflectors and phased array antennas. These antennas offer a lightweight structure, high gain, and low impedance mismatch losses. High gain and low loss are crucial factors in ensuring the antenna delivers low latency and high-quality 5G radio signals. The application of 5G technology becomes more practical and efficient with the capability to adjust the functionality of a single 5G antenna or enable reconfiguration. This reconfigurable technique simplifies the multi-antenna systems and significantly reduces costs, making it more practical and systematic. Furthermore, this reconfigurability is particularly beneficial for satellite applications, as it allows for the reconfiguration of the signal in the event of satellite movement on the space. This paper aims to discuss the historical development of reconfigurable reflectarray antennas, focusing on the innovations in each configurable mechanism. The paper further explores the classification of configurations employed by this antenna, encompassing frequency configuration, radiation pattern, polarization, and hybrid configurations that integrate multiple existing configuration classifications. Finally, the research paper provides a discussion of the most recent research and innovations in the configurable mechanisms of reflectarray antennas.

A single layered high‐gain digital metasurface reflectarray antenna for millimeter wave applications

AbstractA high‐gain digital metasurface reflectarray antenna for 5G FR‐2 band is presented in this letter. The digital metasurface reflector is composed of single‐layered phase quantized meta‐bit unit cell elements. The metabit consists of a split square integrated with a circular ring. Two discretized phase states are obtained by varying the dimensions of the split square and the circular ring, which mimic the metabit‐0 and metabit‐1, respectively. A digital metasurface reflectarray having dimensions of 5.3 5.3 operating in the frequency range of 37–39 GHz is designed, fabricated, and characterized. A linearly polarized antipodal vivaldi antenna spatially feeds the digital metasurface reflectarray. A maximum measured gain of 19.1 dBi is obtained at 38 GHz, with an aperture efficiency of 23%.

W-Band Broadband Circularly Polarized Reflectarray Antenna

We propose a W-band circularly polarized reflectarray antenna in this article, which contains a single-layer reflectarray and a linearly polarized horn feed. To realize the proposed antenna, we designed a novel W-band multi-resonant element containing a Rogers RT5880 substrate with copper patches printed on its both surfaces. Then, a circular reflectarray with 12.25 λ0 (39.1 mm) aperture diameter was designed based on the proposed multi-resonant element, whose center frequency is 94 GHz. We further fabricated the proposed circular reflectarray and tested its performance. In the measured results, we can see that the obtained 1 dB gain bandwidth is 19.1% (91~109 GHz) and the obtained 2 dB gain bandwidth can reach as wide as 27.6% (89~115 GHz). Moreover, the 3 dB axial ratio bandwidth is 13.8% (89~102 GHz). The measured gain of our proposed reflectarray antenna at 94 GHz is 29.1 dBi and the corresponding aperture efficiency can reach as high as 52.0%. Those results show that our proposed antenna may be prospective in wireless communication applications due to its strengths in broadband and high aperture efficiency.

Direct printable X-band low profile broadband reflectarray antenna using copper foils

This work reports on a compact and broadband reflectarray antenna that can be directly applied to the exterior surface of a nanosatellite. The design is composed of an annular ring with a wheel-shaped concentric structure loaded with two circular stubs acting as delay lines for maximum phase angle coverage. The design offers a phase variation of 576° in the X-band along with a peak measured gain of 26.6 dBi and an aperture efficiency of 49.24%. The design also offers low side lobe levels of −13 dB and −18 dB in both E- and H-planes at 11 GHz, respectively. Cross-polarization discrimination is also sufficiently large and is better than −32 dB and −36 dB for E- and H-planes, respectively. Moreover, the proposed printable reflectarray exhibited a 1-dB gain Bandwidth (BW) of 31.5 %. The design is produced by applying copper foils on float glass with a thickness of 2 mm as a proof of concept.

Characterization of a Split Circle Element for Microstrip Reflectarrays

A split circular element is proposed as a unit cell for reflectarray antennas. The unit cell is derived from a circle divided into four equal sectors. The radius of two oppositely located sectors is then scaled by a certain factor to form the proposed shape. The CST Microwave Studio Suite software simulator was used to investigate the performance of the proposed unit cell, which was evaluated using Floquet port excitation. The designed element's reflection phase range was compared to that of a conventional circular patch. Four scenarios of varied substrate characteristics are investigated for the antenna to establish the best performance parameters. The simulations showed that a basic substrate with a thickness of 0.16 mm and a dielectric constant of 3.2, backed by a 3 mm foam with a dielectric constant of 1.05 and a scaling factor of 0.72 offers a wide phase range of 601.3°. The obtained phase slope is 76.37°/mm or 134°/GHz.

W‐band large‐scale high‐gain filtering reflectarray antenna

AbstractThis article presents a W‐band three‐layer reflectarray antenna that can be easily fabricated using printed circuit board (PCB) process. The proposed reflectarray element is composed of substrate integrated waveguide (SIW) structure and slot‐coupled patch. By controlling the length of SIW in each element, the compensation phases required for the reflectarray to generate focused beam at in‐band frequencies are realized. However, at the out‐of‐band frequencies, the elements fail to provide the required compensation phases as the incident electromagnetic wave cannot couple to the SIW. Thus, filtering performance is realized. A circular aperture prototype reflectarray comprising of 5024 elements are employed to yield a high‐gain narrow beam. The measured results show that the proposed reflectarray antenna attains a peak gain of 40.5 dB at 94 GHz with aperture efficiency of 41.3%, and out‐of‐band suppression higher than 22 dB.

Origami-inspired self-deployable reflectarray antenna

Reflector antennas, operating at high frequencies, require a high surface accuracy: deviations from the target geometry accuracy result in a loss of RF performance (e.g., antenna gain and efficiency). As a result, the aperture may need to be larger, or a more complex backing structure must be engineered to achieve the reflector surface accuracy to deliver the equivalent gain of an efficient solid reflector. This would typically increase the mass, the stowed volume, and the design complexity. The design of larger aperture deployable antennas (e.g., Cassegrain, Offset) for SAR (Synthetic Aperture Radar) applications can be challenging for missions where platform size and payload mass are limited.Inspired by the Origami based techniques, Oxford Space Systems (OSS) is currently developing an innovative SAR Reflectarray antenna, targeting the X-Band frequency range, with the aim of achieving a relatively large aperture from a small, stowed volume suitable for a small satellite. The Reflectarray antenna architecture has several potential advantages over other antenna designs. It is a cost-competitive technology with excellent stowage efficiency, which can be further improved with origami-based folding mechanisms/kinematics. It requires a simplified deployment mechanism and in contrast to conventional parabolic reflectors, it does not need a separate backing structure.Until now, work on space deployable Reflectarray antennas (e.g., MARCO, OMERA and ISSARA missions from NASA) have focused on multi-degree of freedom structures, i.e., independent self-actuated hinge driven architectures. This paper presents an elegant single degree of freedom, origami-inspired Reflectarray architecture that does not require actuation on all the hinges. Thanks to its Hold-Down Release Mechanism (HDRM) and spring-loaded hinges, the OSS Reflectarray antenna is self-deployable. It maintains the required flatness accuracy achieved through its novel hinge integrated latching system.The OSS Reflectarray antenna has an 8:1 footprint stowage ratio, which enables installation on small satellite platforms (between 50 kg and 100 kg). The reflectarray has been designed to work in the X-band frequency with dual linear polarization for the concept study. However, the architecture can be scaled up or down to suit other frequency bands, making the OSS Reflectarray compatible with many applications and platforms.

A Low-RCS Circularly Polarized Reflectarray Antenna With a Linearly Polarized Feed

A low-radar cross section (RCS) circularly polarized (CP) reflectarray antenna with a linearly polarized (LP) feed is designed. The out-of-band RCS of the reflectarray for both the TE and TM polarized incident waves is reduced by replacing its ground with an absorptive frequency selective reflector (AFSR). A systematic methodology based on synthesis of the equivalent circuit model (ECM) is presented to expedite the design of the AFSR. The unit phasing element of the reflectarray is designed in such a way that it exhibits minimum coupling between the two orthogonal reflected LP-field components. Moreover, during the reflectarray construction, a novel phase synthesis is used which takes into account possible lowest of the existing mutual coupling while providing quadrature phase difference between the orthogonal LP components with minimum phase error. The proposed design is fabricated using 14×14 phasing elements to experimentally validate the numerically simulated results. The performance of the reflectarray is compared with a conventional reflectarray without the AFSR. It is observed that when the reflectarray is integrated with the AFSR, its gain is reduced only by 1.16 dB. However, its out-of-band RCS is reduced significantly. The 8-dB RCS reduction bandwidth can be observed from 3.55-7.2 GHz (67.9%) and from 11.85-14.21 GHz (18.11%). Moreover, it provides peak co-pol CP gain of 21.62 dBi, aperture efficiency of 41%, and 1-dB gain-bandwidth from 8.68-8.95 GHz, respectively.

A Multipolarized Metal-Only Reflectarray Antenna

A multi-polarized metal-only reflectarray antenna (MPMORA) is proposed and investigated in this paper. The reflectarray is an all-metal planar structure and composed of unit-cells featuring perpendicularly placed size-variable slots carved in a metal sheet. Owing to negligible interactions between orthogonal slots of the unit-cell, a multi-polarized metal-only reflectarray with dual-linear and dual-circular operations can be realized by rotation of a linearly polarized feed with 0°, 45°, 90°, and 135°, respectively. For proof-of-concept, a prototype hosting 441 unit-cells and operating at X-band is manufactured and measured. The testing data reveals that the proposed design can achieve reasonable 1-dB gain drop bandwidths and peak aperture efficiencies for all polarizations, for instance, 15.3% and 45% in the case of right-hand circular polarization (RHCP). Moreover, the 3-dB axial ratio bandwidths for RHCP and left-hand circular polarization (LHCP) are also wide, which are 26% and 39%, respectively. These satisfactory behavior as well as the metal-only configuration make our design a competitive candidate for multi-polarization applications.

3D-printed wideband reflectarray antennas with mechanical beam-steering

Abstract This paper investigates the performance of 3D-printed dielectric reflectarray antennas (RAs) with wideband behavior and beam-steering capabilities. The designed unit cell consists of a single-layer dielectric element perforated with a square hole, whose side is used to control the local variation of the reflection coefficient. The numerical analysis of the unit cell and of first $52\times52$ reflectarray working in Ka-band, whose scanning capabilities are tested just moving the feed along an arc, confirms that the unit cell has a stable behavior with respect to both the frequency and the direction of arrival of the incident field. In view of these promising capabilities, the proposed unit cell is used to design a bifocal reflectarray with the same size and working in the same frequency band of the first one. Its numerical characterization and the measurements of a prototype prove that the RA is able to provide less than 0.8 dB of gain losses over a scanning range of ±40∘ in the vertical plane, while the bandwidth varies between 13.5% and 28%, depending on the pointing direction. The obtained results demonstrate the effectiveness of the proposed approach and highlight the potential of 3D-printing technology for producing high performance, cost-effective RAs with wideband behavior and excellent beam-steering features.

Additively Manufactured Metal-Only Waveguide-Based Millimeter-Wave Broadband Achromatic Reflectarrays

This communication demonstrates additively manufactured metal-only waveguide-based tri-band and broadband reflectarray antennas. The unit cell (UC) is implemented by cascading two metal waveguide sections with different cut-off frequencies (fc1 and fc2 (fc1< fc2)). When illuminated with the feed antenna, the reflectarray provides different reflection paths to compensate for the spatial phase delay over triple bands, fl (fl<fc1), fm (fc1 <fm<fc2), and fh (fh>fc2). By tuning the length of the two waveguide sections and vertically adjusting the position of the UC, the phase-shifting over the triple bands can be independently controlled. In addition, because of the sharp selectivity of the waveguide, a reflectarray with the broadband achromatic feature can be achieved by properly selecting the tri-band’s frequency and the cut-off frequency of the waveguides. A tri-band reflectarray centering at 25 GHz (low-band), 32 GHz (middle-band), and 37 GHz (high-band) is designed firstly to demonstrate the independent beam shaping over triple bands. Then, two waveguide-based reflectarrays with the broadband achromatic feature are designed, which show stable performance from 22 GHz to 38 GHz with a relative bandwidth of 53.3%. The prototypes are conveniently fabricated using additive manufacturing, and their performance is experimentally verified.