Beam-scanning Antenna Research Articles

Experimental Demonstration of Beam Scanning of Dual-Metasurface Antenna

Beam-scanning antennas are employed in a wide range of applications, such as in satellite communications and 5G networks. Current commercial solutions rely mostly on electronically reconfigurable phased arrays, which require complex feeding networks and are affected by high losses, high costs, and are often power-hungry. In this paper, a novel beam scanning architecture employing a pair of planar metasurfaces, for use in thin reconfigurable antennas, is presented and experimentally demonstrated. The structure consisted of a radiative passive (non-reconfigurable) modulated metasurface, and a second metasurface that controls beam pointing, operating as a variable-impedance ground plane. Unlike other existing approaches, surface impedance variation was obtained by on-plane varactor diodes, no vias and a single voltage bias. This paper presents a design procedure based on an approximate theoretical model and simulation verification; a prototype of the designed antenna was fabricated for operation in X band, and a good agreement between measured results and simulations was observed. In the presented simple embodiment of the concept, the angular scanning range was limited to 10°; this limitation is discussed in view of future applications.

Ka-band beam-scanning leaky-wave antenna fed by reconfigurable spoof surface plasmon polaritons.

A leaky-wave antenna (LWA) based on reconfigurable spoof surface plasmon polaritons (SSPP) is proposed for beam scanning in the Ka band, which consists of a reconfigurable SSPP waveguide and a periodic array of metal rectangular split rings. Both numerical simulations and experimental measurements show that the reconfigurable SSPP-fed LWA has good performance in the frequency range from 25 to 30 GHz. Specifically, as the bias voltage changes from 0 to 15 V, we can achieve the maximum sweep range of 24° at a single frequency and 59° at multiple frequency points, respectively. Owing to the wide-angle beam-steering feature, as well as the field confinement and wavelength compression properties derived from the SSPP architecture, the proposed SSPP-fed LWA possesses great potential applications in the compact and miniaturized devices and systems of the Ka band.

A Fixed-Frequency Beam-Scanning Leaky-Wave Antenna Using Phase and Amplitude Control for Millimeter-Wave Applications

A new type of fixed-frequency beam-scanning leaky-wave antenna (LWA) in Ka millimeter-waveband is developed in this article, based on dual control of phase and amplitude. The antenna consists of a groove gap waveguide (GGW) and 80 perturbation units. Each unit contains one patch and a pair of H-shaped slots. By controlling the state of a slot with p-i-n diodes, the phase of the radiated field from each unit can be switched between two opposite phases, called “1” state and “−1” state, while the magnitude of the radiated field remains unchanged. In addition, the radiation strength of each unit can be also turned off to provide amplitude control. The main principle for beam scanning is based on the phase compensation to the perturbation units on the surface of the LWA, combined with 1-bit amplitude control to achieve lower sidelobe levels, so the principle is different from that of the existing fixed-frequency beam-scanning LWAs. The entire antenna structure relies on GGW transmission to reduce dielectric loss in millimeter-waveband, and shows good characteristics of scanning angle and realized gain. In the measurement, a high peak gain of 16.8 dBi and a large beam-scanning range over 110° are achieved.

Low-profile electronic beam-scanning metasurface antenna for Ka-band applications

This article proposes a low-profile real-time electronic beam-scanning metasurface antenna (EBSMA) with hybrid (active and passive) meta-cells in the Ka-band. The EBSMA includes a radiating source, single-layered metasurface with dedicated microcontroller unit, and a power source. The proposed metasurface comprises 4 active subarrays and 11 passive meta-cells, where each subarray comprises 2 × 3 active meta-cells. The metasurface was using a source patch antenna. The EBSMA was realized by integrating one PIN-diode onto each slotted square-ring element in each subarray. Two-dimensional beam scanning was realized by controlling PIN-diode states in real-time for each active subarray using microcontroller hardware. The proposed EBSMA configuration produced a boresight beam at θ = 0° or ±10° tilted beam in the φ = 0° and 90° planes. The antenna achieved 14.18% 3 dB fractional impedance bandwidth with measured realized gains ≈ 10.7 dBi for all states. We fabricated an EBSMA device as proof-of-concept and measured its far-field radiation patterns. Two-dimensional beam-scanning for the proposed metasurface antenna was verified numerically and experimentally.

A Quad-Polarization Reconfigurable Fixed-Frequency Beam-Scanning Leaky-Wave Antenna Based on the Holographic Method for Millimeter-Wave Application

A quad-polarization reconfigurable fixed-frequency beam-scanning leaky-wave antenna (LWA) operating at millimeter-wave Ka-band is presented in this article. A low-loss groove gap waveguide (GGW) structure is employed for low-loss transmission and feeding, above which there locates a metal-covered superstrate. Two rows of inclined slots etched on the metal cover in a staggered arrangement operate as the radiated sources. A modified holographic method is presented, and the hologram can be manipulated by switching the states between “ON” and “OFF” of the p-i-n diodes, and hence the fixed-frequency beam-scanning property with polarization agility of four different polarization states can be realized, including horizontal polarization (HP), vertical polarization (VP), left-handed circular polarization (LHCP), and right-handed circular polarization (RHCP). Besides, measured results of the fabricated antenna are given to verify its performance. The measured peak gains at 30 GHz reach 11.3 dBi in the HP state, 13.0 dBi in the VP state, 11.5 dBic in the LHCP state, and 11.8 dBic in the RHCP state, respectively, with a beam-scanning range of 100° (from −50° to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mathrm{50}^{\circ }$ </tex-math></inline-formula> ), showing good agreement with the simulated results.

Leveraging the Role of Dynamic Reconfigurable Antennas in Viewpoint of Industry 4.0 and Beyond

Industry 4.0 is a digital paradigm that refers to the integration of cutting-edge computing and digital technologies into global industries because of which the state of manufacturing, communication, and control of smart industries has changed altogether. Industry 4.0 has been profoundly influenced by some major disruptive technologies such as the Internet of Things (IoT), smart sensors, machine learning and artificial intelligence, cloud computing, big data analytics, advanced robotics, augmented reality, 3D printing, and smart adaptive communication. In this review paper, we discuss physical layer-based solutions with a focus on high reliability and seamless connectivity for Industry 4.0 and beyond applications. First, we present a harmonized review of the industrial revolution journey, industrial communication infrastructure, key performance requirements, and potential sub-6-GHz frequency bands. Then, based on that, we present a comprehensive review of intelligent tunable dynamic antenna systems at sub-6 GHz as key enablers for next-generation smart industrial applications. State-of-the-art smart antenna techniques such as agile pattern reconfigurability using electrical components, machine learning- and artificial intelligence-based agile beam-scanning antennas, and beam-steerable dynamic metasurface antennas are thoroughly reviewed and emphasized. We unfolded the exciting prospects of reconfigurable dynamic antennas for intelligent and reliable connectivity in application scenarios of Industry 4.0 and beyond such as Industrial IoT and smart manufacturing.

A Dual-Layer Full-Phase Frequency-Selective Surface for Continuous 2-D Beam Scanning

Based on the generalized frequency selective surface (FSS) theory, we prove that the dual-layer dual-polarization transmission FSS can achieve 360° phase coverage at a limited loss. As a verification, a dual-layer dual-polarization full-phase unit cell with vias is proposed, which can achieve a phase range of more than 360° under 2 dB transmission loss. In addition, we innovatively apply the proposed dual-layer full-phase FSS to the design of a continuous 2-D beam scanning antenna based on the Risley prism (RP). This scheme effectively reduces the number of dielectric substrate layers required by the phase shifting surface (PSS), reduces the rotating scanning inertia, and effectively improves the aperture efficiency. The measured results show that the maximum scanning range of the 2-D beam scanning antenna can reach ±46° in the elevation plane and 360° in the azimuth plane. When operating at the center operating frequency of 21 GHz, the maximum gain of the antenna is 35.75 dBi with an aperture efficiency of 44.1%.

Terahertz Wave Conversion From Linear to Circular Polarization by Graphene Metasurface Featuring Ultrawideband Tunability

This paper reports a detailed study of a graphene-based metasurface to function as tunable broadband linear to circular polarization converter in the terahertz gap. This device provides a wide polarization conversion band of 2.25 THz (3.75 THz to 6 THz) with an enhanced fractional 3-dB axial ratio bandwidth (FARBW) of 46.15%. The proposed structure consists of a simple tri-layer configuration where the meta-atom comprises a patterned graphene layer on a gold-backed silicon dioxide substrate. The proposed reflective-type linear to circular polarization converter (RLCPC) exhibits both right-handed and left-handed circular orientations of the reflected wave in two halves of the operating spectrum, further validated in terms of polarization ellipses developed by an inhouse code. The lack of experimental setup at the above said frequencies available to the authors in their country has been paid off by verifying the response using a detailed circuit model. The RLCPC maintains a thickness of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">λ_o</i> /7.69 with a lattice size of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">λ_o</i> /8.33. The structure also promises a stable wideband circular polarization conversion up to 20° and a dual-band circular polarization conversion up to 40° incident angle of the electromagnetic wave. This device can be useful for THz beam scanning antennas, RCS reduction and THz antennas for space and military radar applications.

Circularly Polarized Millimeter Wave Frequency Beam Scanning Antenna Based on Aperture-Coupled Magneto-Electric Dipole

Based on the newly suggested wideband circularly polarized (CP) aperture-coupled magneto-electric dipole (MED), a millimeter-wave (mm-wave) frequency-scanned array (FSA) is proposed in this article. The MED is printed on two substrate layers. The electric dipole is two metal patches with perturbation structure, while the magnetic dipole is two rows of metal vias passing through the top substrate layer. The electric and magnetic dipoles, fed by a coupling slot, excite CP wave. By loading an arc-shaped vias row (AVR) at both ends of the magnetic dipole, the CP bandwidth with axial ratio (AR) less than 3 dB is extended to 40.9%. A new compact wideband transition from the rectangular waveguide (RWG) to the substrate integrated waveguide (SIW) is suggested as the feed structure for the CP FSA. A slow wave structure is etched on the ground of SIW to widen the beam scanning range. A 16-element array is designed and measured. The measured results show that the beam scanning range is 56° over 23–33 GHz band with a peak gain of 19.5 dBi. The CP mm-wave FSA has the advantages of wide scanning angle, low profile, and easy fabrication.

Editorial Message From the Editor-in-Chief

This September issue contains two sets of articles: the Special Issue on Low-Cost Wide-Angle Beam-Scanning Antennas and Regular papers. This Special Issue is motivated by the fact that wide-angle beam-scanning antennas are becoming increasingly more important in many applications, including communications, sensing, and automotive.

Guest Editorial Low-Cost Wide-Angle Beam-Scanning Antennas

One of the key antenna requirements in many modern wireless systems for communications and sensing is wide-angle beam-scanning <xref ref-type="bibr" rid="ref1" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">[1]</xref> . The traditional method to achieve wide-angle beam-scanning is to employ mechanically controlled reflectors or lenses, which are bulky, heavy, and suffer from slow beam scanning speed. Other important limitations of mechanical scanning antennas include the lack of multi-beam scanning capability and the ability to conform with non-planar structures (conformal geometries), which are essential in a number of emerging systems requiring very low-profile antennas. An alternative technique is to employ electronically beam-scanning antennas using passive or active phased arrays <xref ref-type="bibr" rid="ref1" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">[1]</xref> . Main disadvantages of phased arrays are high complexity, high power consumption, and high cost due to a large number of radio frequency (RF) or microwave phase shifters and T/R modules required. The problems worsen for phased arrays at millimeter-wave, sub-THz, and THz frequencies, due to significant losses in phase shifters and feed networks at higher frequencies combined with lower efficiency of power amplifiers <xref ref-type="bibr" rid="ref2" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">[2]</xref> . The digital beamforming approach is even more costly and energy hungry due to the employment of large number of RF modules and digital devices <xref ref-type="bibr" rid="ref1" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">[1]</xref> , <xref ref-type="bibr" rid="ref3" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">[3]</xref> , <xref ref-type="bibr" rid="ref4" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">[4]</xref> .

Varactor-Based Phase Shifters Operating in Differential Pairs for Beam-Steerable Antennas

A concept of varactor-based phase shifter operating in differential pair for beam-steerable antennas is presented in this article. The basic phase-tuning unit consists of a microstrip transmission line and several shorted-stub-terminated varactors loaded on its edge. A pair of these phase-tuning units working in differential mode can achieve a full 360° phase shift, which allows a low loss and simple structure. An accurate equivalent circuit model for this phase shifter is developed for fast calculation allowing the design and optimization of the structure with a genetic algorithm (GA). A pair of phase-tuning units, each including three stub-loaded varactors, is identified as a practical solution to produce a continuously tunable phase difference nearly covering 0°–360°, with two symmetrical 11°-wide blind zones and a maximum insertion loss of 2.04 dB. A 1 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times4$ </tex-math></inline-formula> beam-steerable dielectric resonator antenna (DRA) array is then designed, fabricated, and tested to demonstrate the practicality of the proposed phase shifter. The measured results illustrate that the array is able to continuously scan from <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$- 45^\circ $ </tex-math></inline-formula> to 45°, with a tunable operating frequency band from 4.75 to 5.25 GHz. All these findings suggest that the proposed phase shifter concept is promising and practical to realize beam-scanning antennas.

Dual-Band Beam-Scanning Antenna at Ka-Band by Rotation of Two Transmitarrays

A dual-band beam-scanning antenna by rotation of two transmintarrays (TAs) operating at 20 and 30 GHz has been presented in this letter. TA's unit cell has three metal layers and demonstrates almost completely independent performance at two frequency bands. Two designed TAs have unit cells of different sizes to achieve dual-band with different linear phases. By rotating the two TAs synchronously around the axis orthogonal to the planes of the TAs, it enables two-dimensional (2-D) beam scanning with maximum scanning angles of ±40°. The achieved simulated peak gains are 19.9 dBi, 20.5 dBi and 22.5 dBi, 23.2 dBi at phi = 0°, phi = 90° at 20 and 30 GHz, respectively. The maximum beam scanning losses are 1.7 dB, 2.6 dB and 1.5 dB, 2.7 dB. Moreover, the two beams at the two frequencies can basically point to the same direction at the same time. To validate the design, a prototype is fabricated and tested. The measured results are in good agreement with the simulated results.

Electronically Controlled Fixed-Frequency Beam-Scanning Periodic Leaky-Wave Antenna With Positive-Order-Harmonic Radiations

An electronically controlled fixed-frequency beam-scanning periodic leaky-wave antenna operating in a millimeter-wave band is presented in this letter. An air-filled gap waveguide (GW) base is employed as a millimeter-wave excitation thanks to its low-loss property. Totally, 60 patches in a staggered two-row arrangement are introduced as the radiating elements, which get energies from the GW through longitudinal slots etched on the middle metal layer, and this produces reverse phases in the two rows under a TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sub> -mode excitation. Then, a method by constructing an equivalent phase constant is developed in this letter, and positive-order-harmonic radiation is used to analyze the radiation property. By introducing the period-reconfigurable method, a fixed-frequency beam-scanning performance is achieved. In addition, the developed antenna is fabricated and experiments have been implemented. A beam-scanning range of 70° from −35° to 35° is realized using the positive-order-harmonic radiations at 29 GHz, and the measured peak gain arrives at 16.5 dBi. The design shows possible applications in millimeter-wave communications.

Design and experimental demonstration of a beam scanning lens antenna.

A beam scanning antenna based on an all-metal lens is presented for high-power microwave (HPM) application in this paper. This design includes a feed antenna and two layers of different all-metal lenses, whose prototypes operating at 14.25GHz have been successfully designed and fabricated with an aperture radius of 300mm. A full transmission phase range of 360° can be achieved with a transmission efficiency of over 99% by rotating the cross-slot on the lens elements. The results of the low-power tests depict that the designed antenna can realize a beam scanning range of 120° revolving cone angle with the side lobe below -10 dB and the reflection coefficient less than -16 dB. The high-power tests demonstrate that the power handling capacity of the antenna is higher than 350MW in sulfur hexafluoride (SF6). In addition, both the designed lenses have a bandwidth of more than 100MHz. All the merits show that our designed all-metal lens antenna has a great potential to be applied in HPM systems.

A Low-Profile Programmable Beam Scanning Holographic Array Antenna Without Phase Shifters

Beam scanning antenna brings new opportunities to reduce the data collision of multinode communication in the Internet of Things (IoT). This article proposes a new type antenna design scheme that can be used for IoT relay communication. A programmable beam scanning antenna without phase shifters operating in the X-band is designed to evaluate the feasibility of this scheme. The integrated design of excitation source and phase-modulated structure greatly reduces the profile of the antenna and improves the integrated degrees of freedom with other equipment. By switching the state of the PIN diode loaded on each element, different radiators can be selected and the direction of current polarization on elements can be adjusted to change the radiation phase. Furthermore, the diode states are encoded by the holographic antenna theory and controlled by the FPGA controller to realize programmable beam scanning. One-element, two-element, and 1-D array containing 32 elements are fabricated and measured. The experimental results are in good agreement with the simulation data. The operating bandwidth is 7.5% at 10 GHz while the beam scanning range of the array is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$- 60{^\circ }$ </tex-math></inline-formula> –60°, with a good scanning accuracy and stability. The proposed low-profile beam scanning antenna can provide stable communication services to multiple users and smart devices as a new type of beam scanning array antenna solution for the IoT application, which is beneficial to this field.

A TE₀₁-Mode Groove-Gap-Waveguide-Based Wideband Fixed-Frequency Beam-Scanning Leaky-Wave Antenna for Millimeter-Wave Applications

A wideband fixed-frequency beam-scanning leaky-wave antenna (LWA) operating at the millimeter-waveband is presented in this article. A groove gap waveguide (GGW) supporting base is introduced as a transmission structure of the antenna with a TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">01</sub> -mode excitation, and two rows of longitudinal slots etched on top of the superstrate act as the radiating structures. Two rows of PIN diodes are soldered below the longitudinal slots, so that the long slots can be cut into a group of short slots. By controlling the PIN diodes, the working states of the slots can be switched between “ON” and “OFF.” Then, by selecting proper activation states, the fixed-frequency beam scanning can be obtained. In addition, the developed antenna is verified in practical fabrication and experiment. The experimental results have good agreements with that in simulations. The measured peak gain reaches at 16.8 dBi, and the beam-scanning range more than 70° from 23 to 29 GHz is realized.

Millimeter wave phased array antenna based on highly conductive graphene-assembled film for 5G applications

In the millimeter wave communication frequency band of 5G and coming 6G, the numbers of wireless electronic device will explosively grow. With the commitment of long-term carbon neutrality from various countries, metal replacement in millimeter wave antennas has become an urgent task to meet the requirements of green and sustainable development for the upcoming 5G era. In this paper, for the first time, phased array antennas (PAAs) based on highly conductive graphene-assembled film (GAF) were proposed for 5G millimeter wave applications with the advantages of light weight and high thermal conductivity. We designed and fabricated two PAAs of four-beam directional scanning phased array antenna (DSPAA) and continuous beam scanning phased array antenna (CSPAA). GAF linear antenna array has 212.5% wider operating bandwidth and 5 dB lower side lobes compared to the copper linear array. Based on GAF linear array and Butler matrix feed network, the GAF DSPAA was designed to work at 26 GHz. The GAF DSPAA has four beams with different directions at −28°, −8°, 6° and 22° respectively, showing excellent beam pointing performance. Furthermore, the GAF CSPAA demonstrated the ability to work in a satisfactory beam coverage ranging from −28° to 28°, and achieved a maximum radiation gain of 25.53 dBi at 26 GHz.

Dual-band composite right/left-handed metamaterial lines with dynamically controllable nonreciprocal phase shift proportional to operating frequency

Abstract Dual-band composite right/left-handed transmission lines with the nonreciprocal phase shift approximately proportional to the operating frequency are proposed and demonstrated by using normally magnetized ferrite microstrip lines. The nonreciprocal phase shift can be dynamically controlled by changing the externally applied dc magnetic field. Dynamic change in the nonreciprocal phase gradient along the line enables us to realize dual-band and unidirectional beam-scanning leaky-wave antennas without suffering from frequency-dependent change in the beam direction. A prototype nonreciprocal metamaterial line using polycrystalline yttrium iron garnet was fabricated and measured for verification of our basic concept.

Miniaturized Beam Reconfigurable Reflectarray Antenna With Wide 3-D Beam Coverage

A miniaturized electrical beam-scanning reflectarray antenna providing a directional beam and wide steering ranges with fixed <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\theta $ </tex-math></inline-formula> -polarization is proposed. To accomplish these properties, we devise a new active reflectarray cell that can control both the phase and polarization of incident waves. Accordingly, we can enforce all reflected waves to constructively interfere with each other in all target directions. To feed the proposed reflectarray cells, an omnidirectional monopole antenna is installed at the center of the reflectarray, which illuminates the reflectarray evenly. In addition, because the monopole feeder is directly connected to the reflectarray, we can significantly reduce the overall volume of the antenna down to about <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.5~\lambda ^{3}$ </tex-math></inline-formula> with a small F/D ratio of 0.147. Consequently, the proposed antenna attains a wide scan coverage and directional beam patterns. Moreover, the antenna can also maintain polarization direction stably, which is strongly required for dynamically moving platforms such as drones and unmanned aerial vehicles (UAVs). The experimental results agree well with the predictions, proving the validity of our approach.