Wide-angle Scanning Performance Research Articles

Designing a Novel THz Band 2-D Wide-Angle Scanning Phased-Array Antenna Based on a Decoupling Surface

This paper proposes a novel THz band 2-D wide-angle scanning phased-array antenna (PAA) based on a decoupling surface. The simulated S11 bandwidth under periodic boundary conditions is 106–119 GHz, with stable gain within the bandwidth. The designed decoupling surface effectively reduces the coupling between elements, and the simulated active VSWR performance and ground surface current distribution under periodic boundary conditions confirm this. An 8 × 8 (64-element) planar PAA is modeled and simulated in CST2022 to verify the beam-scanning performance of the PAA. According to the simulation results, a 2-D wide-angle scanning of ±48° is achieved in the 106–114 GHz range, while in the 115–119 GHz range, a wide-angle scanning of ±48° is achieved on the E-plane, and the beam-scanning range on the H-plane reaches ±40°. Moreover, the normal peak gain is stably maintained at 21.9–22.8 dBi, with a normalized radiation efficiency as high as 95%, and the scanning radiation efficiency is higher than 81%. Due to its stable gain and 2-D wide-angle scanning performance, the proposed PAA has a broad application prospect in terahertz wireless communication equipment.

Design and analysis of a metasurface-based wideband wide-angle scanning phased array

This paper presents a wideband wide-angle scanning phased array, which employs Φ-shaped unit cells to form a metasurface (MS) for achieving wideband impedance matching. To optimize the impedance matching performance, a design procedure based on an equivalent circuit model is proposed. A quasi-analytical model based on the equivalent circuit model and the permittivity ϵ r and permeability μ r of the MS properly predicts the scan range of the full structure, and allows for an accelerated design process. The extensive analysis confirms the effectiveness of the MS as the wideband angle impedance matching layer for the antenna array. The MS has demonstrated a positive impact on the wideband wide-angle scanning performance. Finally, a prototype is fabricated and measured, and the experimental results agree well with the simulation results. The proposed array exhibits wide-angle scanning across a 3.5:1 impedance bandwidth (2–7 GHz) with ±60° scan volume in both E-plane and H-plane.

Millimeter-wave Wideband High-isolation Antenna Array Based on End-fire Magnetoelectric Dipole Antenna for 5G Applications

In this paper, a millimeter-wave (mmW) wideband high-isolation wide-angle scanning antenna is presented. The end-fire magnetoelectric (ME) dipole with wideband impedance characteristic and wide beamwidth is selected. Based on the ME dipole, a 1×4 subarray with a stripline feed network is constructed to get higher antenna efficiency. Then, four 1×4 subarrays are adopted to form a 4×4 array to realize the wide-angle scanning performance. Furthermore, to get better isolation between the subarrays, the beam is tilted on the non-scanning plane; in addition, the resonant split rings are added on the background of the subarrays. With these two measures, the isolation between the subarrays can be effectively reduced, with more than 20 dB over the entire bandwidth. Owing to the wide beamwidth of ME dipole and high isolation between the subarrays, the 4×4 array can obtain the wide-angle scanning characteristic. The final antenna covers an operating bandwidth of 19.5% (24.25-29.5 GHz) with return loss more than 10 dB, which can meet the band in the 5G standard. The beam can scan approximately ±55∘ with a realized gain reduction under 3 dB within the wide operating bandwidth. Also, the simulated radiation efficiency of the array is more than 77% over almost the entire band. The antenna will be a potential candidate to be applied in 5G applications.

A Study on Millimeter-Wave Magneto-Electric Dipole Phased Arrays for 5G Dual-Band Applications

Beam steering characteristics of millimeter-wave substrate-integrated magneto-electric (ME) dipole phased arrays with large sizes are investigated in this article. The formation mechanism of the guided waves traveling along the planar ME-dipole array geometry is revealed with the use of a linear array model in simulation, which not only provides an effective method of predicting the blind angles for the ME-dipole phased arrays but also confirms the superior wide-angle scanning performance of the arrays. An 8 × 8 ME-dipole phased array is then designed, fabricated, and tested, whose measured beam scanning range without the blindness in both the E- and H-planes is ±60° over the frequency range between 23.5 and 27.5 GHz and is ±50° over the range between 27.5 and 29.5 GHz. A gain of up to 23.6 dBi and stable radiation patterns are also achieved. With the simple single-layered configuration and the wide-angle scanning ability over the wide operating band of 22.6%, the ME-dipole phased array would be an attractive candidate for the millimeter-wave dual-band applications in the fifth generation (5G) mobile communications.

Two-Dimensional Image Theory-Based Surface-Mounted Linear Array With Azimuth Wide-Angle Scanning Performance

This article focused on broadening the azimuth plane scanning range of surface-mounted linear arrays. First, 14 kinds of basic radiation models were theoretically analyzed, and the basic model with a 180° covered main lobe was pointed out. Afterward, a wide-beam surface-mounted antenna was designed using an in-phase-reflection electromagnetic bandgap structure based on the selected element model. Finally, an azimuth plane wide-angle scanning linear array with wide-beam surface-mounted elements was arranged, decoupled, and evaluated. This array can scan its beam in the range of 90° ± 85° in the azimuth plane with a 3 dB gain fluctuation, which verified the effectiveness of the proposed theoretical model.

A Ferrite-Loaded Ultralow Profile Ultrawideband Tightly Coupled Dipole Array

A dual-polarized ferrite-loaded ultrawideband tightly coupled dipole array (TCDA) with an extremely low profile is presented. A novel ferrite grid with high relative permeability and permittivity characteristic is loaded between the antenna and the ground plane, which expands the low-end of operation bandwidth and reduces the overall profile, simultaneously. An X-shaped frequency selective surface (FSS) is utilized as a special band-stop filter to improve the realized gain at higher frequencies. Meanwhile, the proposed array utilizes a microstrip (MS) to coplanar stripline (CPS) uniplanar double-Y balun to achieve unbalance&#x2013;balance transformation and impedance matching. A thin meta-surface-based wide-angle impedance matching (MS-WAIM) layer is introduced to improve the beam-scanning ability. Simulated results show that the proposed antenna is able to operate over a 10:1 bandwidth (0.2&#x2013;2 GHz) with active VSWR &#x003C; &#x0007B;2, 2.6, 3.4&#x0007D; while scanning up to &#x0007B;broadside, 45&#x00B0;, 60&#x00B0;&#x0007D;, respectively. Most of all, the overall antenna profile is only 62.5 mm (<inline-formula> <tex-math notation="LaTeX">$0.042\lambda _{\mathrm {L}}$ </tex-math></inline-formula>) at the lowest operating frequency, which is known to be the thinnest 10:1 ultrawideband array with wide angle scanning (&#x00B1;60&#x00B0; in E- and H-plane) performance. A prototype of <inline-formula> <tex-math notation="LaTeX">$6 \times 8$ </tex-math></inline-formula> array is simulated, fabricated, and measured. Good agreement is achieved between the simulated and measured results.

Design and Analysis of a Novel Wide-Angle Scanning Stub-Loaded Cavity Array Element

A novel design methodology is presented to mitigate scan blindness in cavity antenna arrays without the need for any changes on the radiating structure itself. For a first proof-of-concept demonstration, a fully PCB-compliant dual-polarized cavity element is loaded by vertical stubs to manipulate the dispersion characteristics in the aperture plane. In contrast with its conventional cavity antenna counterpart, the proposed stub-loaded unit cell element shows through scattering and eigenmode analysis that the vertical stubs may effectively enhance the antennafs wide-angle scan performance by preventing the onset of surface and leaky wave resonances. Owing to this additional design freedom, an element gain improvement of at least 1 dB is achieved, due to a truly TE and TM mode-free characteristic along the lateral directions. A dual-polarized 11&#x00D7;11 array prototype was implemented. The measurement results are in very good agreement with those obtained by full-wave simulations. The realized stub-loaded cavity element exhibits reflection coefficients lower than -10 dB with a very low inter-port coupling &#x003C;-40 dB across the frequency range from 26.8 GHz to 32.7 GHz. Moreover, the co-polarized embedded elements are close to the ideal cos(&#x03D1;)-pattern for 60&#x2218; E-and H-plane scans from 28 GHz to 31.5 GHz without oversampling the aperture.

Wide-angle scanning linear phased arrays based on wide-beam magneto electric dipole antenna

Microstrip phased array has aroused interest of many researchers because of its beam agility. However, a big problem for typical microstrip array is that its main beam can only scan from about –50° to 50°, with a gain loss of 4-5 dB. Meanwhile, the relatively narrow operating bandwidth of microstrip antenna is also a problem in application. These flaws have dramatically limited its applications and spawned many studies on phased array with wide-angle scanning capability. Several methods have been proposed to broaden the scanning coverage of phased array, such as utilizing pattern-reconfigurable antenna as an element of array, taking wide-beam antenna as the element of array, and adopt metasurface as the top cladding of array. However, most of existing researches mainly focus on achieving wide-angle scanning performance within a relatively narrow bandwidth. A phased array that possesses wide-angle scanning capability at both main planes within a relatively wide bandwidth is highly desirable. In this paper, a wide-beam magnetoelectric (ME) dipole antenna is proposed. It consists of an ME dipole antenna in the form of microstrip patch and a pair of magnetic dipoles. Metallic through holes integrated with patches and ground are utilized to form magnetic currents. Extra magnetic dipoles are added to broaden the 3-dB beam-width. The simulated results reveal that the 3-dB beam-width of the proposed antenna is greater than 107° in the E-plane (9 GHz–12 GHz) and 178° in the H-plane (7 GHz–12 GHz) respectively. The impedance bandwidth of the proposed antenna is 53.26% from 7.3 GHz to 12.6 GHz (VWSR &lt; 2). Based on the proposed antenna element, two linear phased arrays are fabricated and measured. To test the wide-angle scanning capability of the arrays, each antenna element is simply fed with alternating currents with identical amplitude and linearly increasing phases. The measured results reveal that the wide-angle scanning capability of H-plane array and E-plane array can be obtained from 9 GHz to 12 GHz. The scanning beam of the H-plane array can cover the range from -90° to 90°. The scanning beam of the E-plane array can cover the range from –70° to 70°. The impedance bandwidth of the central antenna is 27.03% for the H-plane array from 9.6 GHz to 12.6 GHz (active VWSR &lt; 2.5) and 36.36% for the E-plane array from 9 GHz to 13 GHz (active VWSR &lt; 2) respectively. Hence, the proposed method can be used as a reference for designing a wide-beam antenna and wide-angle scanning phased array and the designed phased arrays can be applied to X-band radar systems.

Wide-Band and Wide-Angle Scanning Phased Array Antenna for Mobile Communication System

A wide-band phased array antenna with wide-angle scanning capability for mobile communication system is proposed in this article. An air cavity is properly embedded into the substrate under each array element. This method is very simple and can efficiently enhance wide-angle scanning performance by improving the wide-angle scanning impedance matching (WAIM) and realizing the beam-width of elements in the array. Besides, the operating bandwidth is also extended with the proposed approach. The wide-angle scanning capability is analyzed and verified by both the linear array antennas (on large ground planes in detail) and the planar array. Two <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1\times 8$ </tex-math></inline-formula> linear arrays and one <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$8\times 8$ </tex-math></inline-formula> planar array are demonstrated, which achieve the beam scanning of around ±60° with a realized gain reduction under 3.5 dB in the wide operating bandwidth (37.4%). Furthermore, the beam in the E-plane can scan over ±70° with a realized gain reduction under less than 3 dB. Two linear array prototypes with wide-angle scanning capacity in two planes are fabricated and characterized, yielding good performance within overall operational bandwidth. The measured results align very well with the simulated. The proposed wideband phased array with large scanning coverage is a promising candidate for 5G mobile communications.

A Wideband Phased Array With Broad Scanning Range and Wide-Angle Impedance Matching

For wide-angle scanning phased arrays, the efficiency of active elements is deteriorated with the increase of mutual impedance. This article demonstrates an effective strategy to control the mutual impedance among array elements by canceling the major coupling effect. The implemented wideangle impedance matching (WAIM) of a wideband phased array verifies the validity of the proposed strategy. For the array element, to obtain wide-angle radiation and wideband characteristic, parallel slots with unequal lengths are deliberately etched on a low-profile substrate integrated cavity (SIC). The mutual impedance between two arbitrary elements is remarkably controlled and compensated by canceling the major coupling effect, which is realized by etching symmetrical slots and loading periodical loops within each element. With the controlled mutual impedance, the proposed array possesses excellent wide-angle scanning performance. Both the simulated and measured results indicate that the designed array steers its main beam from -70° to +70° in the xoz azimuth plane in a broad frequency range from 8.0 to 9.5 GHz. The active S-parameter of each element remains lower than -10 dB in the operating band while the array scans. Due to the implemented WAIM, the total efficiency of the array exceeds 90% during the scan and the fluctuation of realized gain is less than 3 dB.

A Planar Wide-Angle Scanning Phased Array With $X$ -, $Ku$ -, and $K$ -Band RCS Reduction

This communication presents an artificial magnetic conductor (AMC) structure-loaded phased array with broadband low-RCS and wide-angle scanning performance. A substrate integrated with the cavity-backed antenna with wide beamwidth and decoupling cavity is used as the basic array element to increase the field-of-view scanning range of arrays. Meanwhile, a checkerboard-shaped AMC structure with a broadband region of 180° (±37°) phase difference is designed and loaded around the array to reduce its RCS in and out of the band. This communication is validated through measurements that matched well with simulations. The proposed array operates at 10.8 GHz and provides a wide scanning region from −70° to +70° in the H-plane with particularly small gain fluctuation (±1.5 dB). Moreover, the backscattering of the proposed array can be reduced to −6 dB for both TE and TM polarizations, covering the $X$ -, Ku -, and $K$ -bands. The proposed approach has the potential application in smart skin designs due to its low profile, powerful scanning ability, and broadband RCS reduction.

Impedance Matching Design of a Low-Profile Wide-Angle Scanning Phased Array

In this paper, an effective method aimed at reducing the mutual impedance among array elements is developed to realize wide-angle impedance matching (WAIM) for planar phased arrays. According to the property of the coupling field, the inherent field distribution at apertures of each element is properly regulated so that the mutual impedance between two arbitrary elements can be substantially reduced. Based on the analysis of the impedance matrix for the equivalent microwave network, the required WAIM can be implemented with such minified mutual impedance. With the proposed method, a low-profile linear phased array with $1 \times 10$ uniform elements is designed and manufactured. For the presented array, the wide-angle scanning performance is attained from the joint effect of the spatial radiation and the surface-wave diffraction. To achieve WAIM, the inherent field of each element is deliberately adjusted according to the distribution of the guided TM surface wave, which acts as the dominant coupling field. Both simulated and experimental results indicate that the proposed phased array can steer its main beam from −81° to +81° in the azimuth plane, with peak realized gain fluctuation less than 3.5 dB. Particularly, besides the broad range of scan, all the active S-parameters are controlled less than −10 dB in the fixed operating band for all scanning angles.

Broadband Low-RCS Phased Array With Wide-Angle Scanning Performance Based on the Switchable Stacked Artificial Structure

A novel and simple switchable stacked artificial structure (SAS) is proposed and studied in phased arrays to realize a smart integration of broadband radar cross section (RCS) reduction and scanning range expansion. The proposed SAS is composed of a frequency selective surface (FSS) and a metamaterial absorber (MA). The lower part of the SAS can be switched between an FSS and a surface-waveguide (SWG) high-impedance surface (HIS) hybrid structure which can be used for wide-beam antenna design and array mutual coupling reduction. The upper part of the SAS can be seen as an MA. A linear phased array is presented and investigated based on the proposed switchable SAS. When the phased array is switched to its working mode, the SWG-HIS hybrid structure plays an important role to support a wide-angle scan from −75° to +75° with low sidelobes. When the phased array is shut down, the FSS-MA stacked structure can realize a low-RCS design in the frequency range of 0–11.2 GHz. An array prototype which operates at 4.6 GHz is fabricated and measured. The measured results have validated the radiation and scattering performance of the designed phased array.

A Study of a Wide-Angle Scanning Phased Array Based on a High-Impedance Surface Ground Plane

This paper presents a two-dimensional infinite dipole array system with a mushroom-like high-impedance surface (HIS) ground plane with wide-angle scanning capability in the E-plane. The unit cell of the proposed antenna array consists of a dipole antenna and a four-by-four HIS ground. The simulation results show that the proposed antenna array can achieve a wide scanning angle of up to 65° in the E-plane with an excellent impedance match and a small S11. Floquet mode analysis is utilized to analyze the active impedance and the reflection coefficient. Good agreement is obtained between the theoretical results and the simulations. Using numerical and theoretical analyses, we reveal the mechanism of such excellent wide scanning properties. For the range of small scanning angles, these excellent properties result mainly from the special reflection phase of the HIS ground, which can cause the mutual coupling between the elements of the real array to be compensated by the mutual coupling effect between the real array and the mirror array. For the range of large scanning angles, since the surface wave (SW) mode could be resonantly excited by a high-order Floquet mode TM−1,0 from the array and since the SW mode could be converted into a leaky wave (LW) mode by the scattering of the array, the radiation field from the LW mode is nearly in phase with the direct radiating field from the array. Therefore, with help from the special reflection phase of the HIS and the designed LW mode of the HIS ground, the antenna array with an HIS ground can achieve a wide-angle scanning performance.

Improving Wide-Angle Scanning Performance of Phased Array Antenna by Dielectric Sheet

The method to improve the wide-angle scanning performance of the phased array antenna is studied and presented. The proposed method is realized by the dielectric sheet to reduce the size of the wide beam antenna and mutual coupling between the elements in the array antenna. The size of the antenna element is reduced by the dielectric sheet which is arranged on the top of the feed slot. The mutual coupling of the array antenna is improved by the dielectric sheet. And, the wide-angle impedance matching performance is improved by the above method. The operating frequency band of the E- and H-plane-phased array antennas is from 3.2 to 3.8 GHz. The main beams of the E-plane scanning array antenna can scan from -90° to +90° with the gain variation less than 3 dB. The main beams of the H-plane scanning array antenna can scan from -70° to +70° with the gain variation of less than 3 dB. The E- and H-plane scanning linear array antennas with nine elements are fabricated and tested. The measured results have a good agreement with the simulated results.

Dual-Band Wide-Angle Scanning Phased Array Composed of SIW-Cavity Backed Elements

In this communication, an aperiodic dual-band phased array with wide-angle scanning performance is presented. A substrate integrated waveguide cavity-backed antenna, which has wide beamwidths at 4.8 and 5.8 GHz, is used as the basic array element. The phased array contains eight subarrays with an equally spaced arrangement, and each subarray is arranged in a symmetric structure. Theoretical and optimization methods, in which the main beams of the subarray and the full array are coincident and the maximum sidelobe of the full array points to the null of the subarray, are proposed for sidelobe reduction. Based on the optimized results, the main beam of the phased array can scan from −75° to +75° at both the frequency bands, and the array supports the 3 dB beam coverage from −86° to +86° at the low-frequency band and from −82° to +82° at the high band, respectively. The phased array is simulated, fabricated, and measured. The measured results validate its wide-angle scanning performance.

Study on Wide-Angle Scanning Linear Phased Array Antenna

Two wide-angle scanning linear array antennas (E- and H-planes scanning linear array antenna) are studied and presented. In order to improve the wide-angle scanning performance of the phased array antenna, a wide beamwidth U-shaped microstrip antenna with the electric walls is designed. The wide-angle scanning linear array antennas are studied in the frequency band from 3.2 to 3.8 GHz. The 3 dB beamwidth of the antenna is 140° in the E-plane scanning linear array center and 220° in the H-plane scanning linear array center at 3.5 GHz. The main beams of the H-plane scanning linear array antenna can scan from −90° to +90° with a gain fluctuation less than 3 dB and a maximum sidelobe level (SLL) less than −5 dB. Simultaneously, the main beam of the E-plane scanning linear array antenna can scan from −75° to +75° with a gain fluctuation less than 3 dB and SLL less than −5 dB. The H- and E-planes scanning linear array antennas with nine elements are fabricated and tested. The measured results have a good agreement with the simulation results.

A Wide-Angle Scanning Phased Array With Microstrip Patch Mode Reconfiguration Technique

A method based on the microstrip patch mode and reconfiguration technique is analyzed, studied, and applied to wide-angle scanning phased arrays. First, a summative evaluation of microstrip patch modes available for wide-angle scanning or near endfire has been made. Second, to validate this new method, a multilayer microstrip patch element is established and its resonant modes TM01 and TM20 are excited. Third, a reconfigurable technique is used to reconfigure the above resonant modes and a wide joint 3-dB beam coverage is obtained. Fourth, a prototype of $1\times 4$ uniform linear phased array with the above reconfigurable elements is proposed. The prototype operates at 5.8 GHz and its main-beam direction can scan from −75° to +75° in the elevation plane with a gain fluctuation less than ±1 dB. Finally, in order to reduce the sidelobe levels, a hybrid particle swarm optimization algorithm is used to optimize the excitation amplitudes and phases. The measured results show an excellent wide-angle scanning performance, which validates the effectiveness of the proposed method.

Planar Wide-Angle Scanning Phased Array With Pattern-Reconfigurable Windmill-Shaped Loop Elements

A wide-angle scanning planar phased array with pattern-reconfigurable windmill-shaped loop elements has been designed. Each element has a four-port windmill-shaped structure over a high-impedance surface, and it can steer the main beam in four different space quadrants by exciting one port at a time. A 16-element planar (4 × 4) array is fabricated and measured to demonstrate the wide-angle scanning performance of the array. The results show that the fabricated array is able to scan its main beam up to 72° and supports a 3-dB scanning coverage up to 92° in each quadrant. In addition, input amplitudes and phases for the array are optimized with a hybrid particle swarm optimization algorithm to enhance the array scanning performance.

2-D Planar Wide-Angle Scanning-Phased Array Based on Wide-Beam Elements

This letter presents a novel two-dimensional planar-phased array with wide-angle scanning performance. A parasitic pixel layer-based antenna is used as the array element. The antenna optimized with a multiobjective genetic algorithm has wide beamwidth in both xoz- and yoz-planes. A 64-element planar (8 × 8) array is fabricated and measured to validate its scanning performance. With the uniform and optimized inputs, respectively, applied to the high- and low-elevation areas, the measured results show that the phased array is able to scan its main beam from -75° to +75° in both xoz- and yoz-planes, and it supports 3-dB beam coverages from -85° to +85° in the xoz-plane and from -85° to +80° in the yoz-plane.