Beam Coverage Research Articles

Broadband and Wide-Angle Scanning Capability in Low-Coupled mm-Wave Phased-Arrays Incorporating ILA With HIS Fabricated on FR-4 PCB

This paper presents a compact millimeter-wave (mm-Wave) phased array incorporating inverted-L antenna (ILA) with high-impedance electromagnetic surfaces (HIS) based on single-layer FR-4 PCB for user equipment (UE). In order to realize mm-Wave UE in low production cost, the design methodology of phased array antenna in single-layer FR-4 PCB is proposed without any additional packaging process. The presented antenna consists of low-coupled antenna element and low loss feeding networks in compressed linear array configuration with 0.39λ0 inter-element spacing. First, in order to realize broadband characteristics, the ILA is integrated with one-dimensional electromagnetic bandgap (1-D EBG) structures featuring HIS via slow-wave behavior. Due to high-impedance properties of the embedded via wall structures in common ground plane between each antenna element, the mutual coupling path through surface-current can be reduced. Second, in order to minimize leakage power caused by surface-waves, low loss coplanar waveguide ground (CPWG) feeding networks with via wall structures and island-shape pads are realized. The fabricated 4-elements and 8-elements phased array antennas including antenna element and feeding network based on FR-4 PCB achieve wide 3 dB beam coverage while featuring low beam squint in the Ka-band. In order to investigate over-the-air (OTA) system performance at three beam steering scenarios (boresight and ±60° scan angle), the measured maximum error vector magnitude (EVM) in QPSK modulation scheme is 16.6%. The coverage efficiency beyond 50% for the realized gain of −1.5 dBi from 26 to 36 GHz is demonstrated.

Fiber-Enabled Optical Wireless Communications With Full Beam Coverage

This work proposes a fiber-enabled optical wireless communication (FE-OWC) system for bidirectional communications between the base station (BS) and a number of mobile user terminals (UTs) via full beam coverage, aimed at facilitating ultra-high data rate communications. The FE-OWC system comprises optical antennas, optical chains, and baseband units at both BS and UTs. The innovative optical antenna consists of an array of fiber ports and a transceiver lens, which can form a number of transmit and receive optical beams and provide a full beam coverage for simultaneous downlink and uplink connections with a number of UTs, respectively. We present analysis to characterize downlink and uplink channel models and gains, including both optical and electrical parts, between the BS and UTs and conduct a complete link budget analysis. We further design downlink and uplink multiuser multiple-input multiple-output (MIMO) as well as massive MIMO transmission protocols and develop asymptotically optimal schemes for a large number of fiber ports. Numerical results illustrate that the FE-OWC system has the potential to support over 10 Gbps data rate per UT and Tbps system throughput required in future 6G mobile communication systems.

A 3-D-Printed Multibeam Spherical Lens Antenna With Ultrawide-Angle Coverage

A 3-D printed multibeam spherical lens antenna with 2-D ultrawide-angle coverage is presented in this letter. The two-layer spherical dielectric lens can be fabricated easily by 3-D printing technology based on the effective medium theory. The circularly polarized U-slot patch antenna is introduced as the feed for the spherical lens due to its good radiation performance and compact configuration. The 2-D beam scanning can be achieved by switching the multiple feed elements, which are positioned around the spherical lens. Experimental results indicate that the −10 dB impedance and the 3 dB axial ratio (AR) bandwidth is over 7.7to 8.2 GHz, and the isolation between the adjacent feeds is higher than 20 dB. The 46 stable radiating beams are able to achieve a beam coverage of 360° of in the azimuth plane and almost 90° in the elevation plane.

Method to calculate the power-flux-density mask radiated by NGSO constellation system

The emerging fleet of non-geo stationary orbit (NGSO) constellation is composed of up to thousands of NGSO satellites, with highly dynamic multi-dimensional characteristics such as in the domains of space, time, frequency spectrum, and coding, etc. Therefore, the time-varying interference is inevitably caused to other radio systems (or services) in the sharing frequency. The problem of how to calculate the maximum emission from the NGSO constellation is solved in this paper. The beam gain patterns of the NGSO system, the beam configuration and coverage, and the minimum separation angles at terminals (data points) are introduced on the basis of the calculation framework of ITU-R S.1503-3. The general method of the power-flux-density(PFD) mask can also simplify the calculation process. An example of PFD mask is simulated in this paper. It can be known from the analysis that the more detailed operating parameters of the system, especially such as the handover strategy, the interference avoidance or mitigation strategy to be obtained, the more accurate results can be simulated, which is closer to the real value of the system working. The method can be used to calculate the PFD envelope in order to participate in the calculation of the downlink equivalent PFD.

Conformal Antenna Array Design Using Aperture Synthesis and On-Platform Modeling

Conformal antenna arrays have long represented an attractive solution to challenges imposed by an electromagnetic aperture on an aerospace platform. This allows designers to trade between array positioning and geometry, and avoids the significant aerodynamic drag of a planar array. This is hampered by the expense of the design and computational modelling required to ensure that a conformal array will meet its performance requirements. The proposed approach uses raycasting techniques to predict the rectilinear projection of a conformal aperture onto the farfield to calculate the maximum achievable beam coverage (aperture maximum directivity envelope). In order to compare aperture projection with the performance of the modelled arrays in a consistent manner, the steering efficiency (SE), which is the fraction of the farfield steerable to within 3dB of the maximum directivity, was calculated for the aperture, stacked patch, and conical monopole elements. The stacked patch elements demonstrated a SE of 18% over the steering plane compared with 40% for the arbitrary directional elements, and the optimum of 38% for the aperture overall. The Conical monopole elements achieved a SE of 8%, compared to 20% for the measured elements, and 33% achieved with arbitrary omnidirectional elements. These results demonstrate that, for both omnidirectional and directional elements, the aperture projection method offers a compelling tool for conformal array design, which is consistent with the achieved array performance for the stacked patch and conical monopole elements.

Wideband Printed Half Bow-Tie Antenna Array Based on a Quad-Mode Reconfigurable Feeding Network for UAV Communications

In this article, a wideband printed half bow-tie antenna array based on a quad-mode reconfigurable feeding network for unmanned aerial vehicle (UAV) communications is presented. The proposed array consists of four printed half bow-tie antennas in the top substrate, two supports with a tapered balun, and a reflector with the reconfigurable feeding network in the bottom substrate. For UAV communications caused by wide beam coverage, the proposed reconfigurable feeding network using one single-pole-four-throw (SP4T) and two single-pole-three-throw (SP3T) switches can adjust the phase and amplitude to the antenna element. By controlling the switches, the proposed array can be operated on four linear polarization modes. The simulated and measured results prove the proposed array reconfigurability of the main beam in four directions with 45° steps in the azimuth plane. In addition, the proposed array achieves the wide 10-dB impedance bandwidth of approximately 29.6% (1507 MHz) from 4.1 to 5.6 GHz. The peak gain and half-power beamwidths (HPBWs) on azimuth and elevation planes of the proposed array are approximately 5.9 dBi, 240°, and 99°, respectively. The overall volume size of the proposed array is $60\times 60\times18.3$ mm3 ( $\sim \lambda _{0}\times \lambda _{0}\times 0.3\lambda _{0}$ at 5.1 GHz).

Correction to “Beam Coverage Comparison of LEO Satellite Systems Based on User Diversification”

In the above article <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 authors inadvertently did not include the affiliation of the first author. The name of the organization is “University of Chinese Academy of Sciences.”

Context-and-Social-Aware Online Beam Selection for mmWave Vehicular Communications

Millimeter-wave (mmWave) bands are expected to be an important choice for future vehicular communication to support Gbps links for reliable data transfer in high-rate applications. The recent online learning technologies addressed the problem of fast beam tracking by exploiting user location information and mining received data in mmWave vehicular systems to adapt to the vehicle's environmental situation. However, the fairness and efficiency over mmWave beams are difficult to maintain on the move, especially for high-density traffic, since the number of available beams is quite limited by hardware and cost for current antenna arrays. Fortunately, the social structure of preferences between the neighboring smart cars and their passengers can be leveraged to improve the beam coverage efficiency by performing the broadcast transmission via a single beam. In this article, we propose a double-layer online learning algorithm, namely, context- and social-aware machine learning (CSML), that is based on the context and social preference information of vehicles and passengers, to realize fast beam access with broadcast coverage in mmWave communication systems. Based on the multiarmed bandit model, CSML embodies the selection of appropriate beams in the first layer and steers the broadcast angle along these beams in the second layer by aggregating the received data. Furthermore, CSML needs to adjust the timing of exploration and exploitation based on the social information, i.e., the probability of vehicles meeting with each other that have the same preference. Finally, we perform an extensive evaluation using realistic traffic patterns and show that CSML increases the efficiency of mmWave base stations by using social data and can achieve near-optimal system performance.

Systematic Beam Management in mmWave Networks: Tradeoff Among Beam Coverage, Link Budget, and Interference Control

In this paper, we study the beam management problem in mmWave networks from a systematic perspective. Instead of maximizing the network performance in terms of user sum-rate, we improve the beam coverage, which could potentially reduce beam tracking overhead for mobile users. Moreover, to compensate the severe signal attenuation in mmWave bands, we configure the beam to meet the user link budget requirement. To reduce the interference among users, we take the inter-beam interference from both main-lobe and side-lobe into consideration. Overall, we formulate our beam management scheme as a non-linear integer optimization problem. By deliberately transforming it to a geometric optimization problem and designing a rounding method, we develop a suboptimal solution, with low computational complexity. Based on this, we further design a scheduling user set refining method, which can assist user scheduling in the MAC layer, to make the beam configuration request within the antenna capability. Extensive simulation results demonstrate that our proposed algorithm could manage the beam on-line, while satisfying beam configuration requests for beam coverage, link budget, and inter-beam interference control.

Research on ultrasonic phased array inspection technology of small diameter tube based on Ultravision simulation technology

According to the principle of ultrasonic phased array inspection, the ultrasonic phased array inspection simulation experiment is carried out on the butt weld of small diameter tube of power plant boiler by using the Ultravision software, which mainly includes the simulation of acoustic beam coverage and focused beam distribution. From the simulation test results, it can be concluded that: through the simulation of the acoustic beam coverage, the accessibility and coverage of the ultrasonic phased array acoustic beam can be simulated, and the applicability of the detection process can be verified and optimized; Through the simulation of focusing beam distribution, the distribution of the beam focus in the butt weld of the small diameter tube can be determined, which can guide the selection of focusing mode in the detection process and improve the signal-to-noise ratio of defect detection.

Two‐Dimensional Electromechanically Transformable Metasurface with Beam Scanning Capability Using Four Independently Controllable Shape Memory Alloy Axes

AbstractThe advancements in wireless technology, especially in radar detection, where accurate target information is critically needed, have set new standards for antenna subsystems that demand higher gain and full scanning coverage in both the azimuth and elevation planes while maintaining lower cost and design simplicity. The conventional phased array usually requires complex feeding circuitry with large spatial occupancy that renders the system bulky and expensive; therefore, a reconfigurable metasurface may be a suitable alternative. Earlier research outcomes have shown different kinds of reconfigurability in designing metasurfaces for beam steering. Designing electrically reconfigurable metasurfaces using PIN diodes, varactor diodes, etc., is a well‐known approach; however, these methods suffer from poor isolation of switches, limited power handling due to nonlinearities, high cost, and complicated biasing networks. This work proposes a novel electromechanically transformable metasurface working as a beam‐steering surface with a wider tuning range in the azimuth plane and a simplified independent switching mechanism. The incorporation of four shape memory alloy (SMA) actuator springs allows swift movements in eight different directions. The electrical control of the pitches of the four springs oriented along the four different SMA axes enables adequate mechanical transformation of the 2D metasurface to obtain beam coverage capability.

Low-Complexity Multicast Beamforming for Millimeter Wave Communications

To develop a low-complexity multicast beamforming method for millimeter wave communications, we first propose a channel gain estimation method in this article. We use the beam sweeping to find the best codeword and its two neighboring codewords to form a composite beam. We then estimate the channel gain based on the composite beam, which is computed off-line by minimizing the variance of beam gain within beam coverage. With the estimated channel gain, we propose a multicast beamforming design method under the max-min fair (MMF) criterion. To reduce the computational complexity, we divide the large antenna array into several small-size sub-arrays, where the size of each sub-array is determined by the estimated channel gain. In particular, we introduce a phase factor for each sub-array to explore additional degree of freedom for the considered problem. Simulation results show that the proposed multicast beamforming design method can substantially reduce the computational complexity with little performance sacrifice compared to the existing methods.

Determination of Coverage Oscillation for Inclined Communication Satellite

The communication engineers need to evaluate footprint movement to deploy a ground station. Geostationary communication satellite’s inclination angle causes the movement of a satellite footprint. The calculation of the inclination angle requires complex astronomical knowledge and mathematical calculations. On the other hand, a satellite communication engineer does not need a very accurate inclination angle value to design a ground station for required service availability. We propose a practical method called trigonometric curve fitting for the inclination to solve the problem. The past and the future value of inclination can be evaluated by using the curve-fitting method. It is a simplified practical method and does not need advanced orbital dynamics knowledge. The orbit geometry and evaluated inclination angle are used for estimation of a coverage area movement. A satellite communication engineer can evaluate coverage area oscillation quickly and design a better link for an inclined orbit satellite by using the proposed method. We have evaluated the inclination angle of the communication satellite Sat-1 with the proposed method. Sat-1 spot beam movements and wide beam coverage area movements are estimated to obtain EIRP and G/T fluctuation for link budget purposes. The proposed method provides the results that are consistent with the results of measurements and the results of satellite operators’ professional tools.

Research on Ultrasonic TOFD Testing Method of Electron Beam Weld

With the development of aerospace technology, electron beam welding technology has become an important part of the welding field. More and more aircraft and spacecraft parts adopt electron beam welding technology. However, in the process of electron beam welding, due to the influence of the incident angle of the electron beam, the deviation of the weld bead and the electromagnetic field, it is easy to produce defects such as unfused and blowholes. Therefore, it is necessary to conduct a non-destructive testing study on the electron beam weld. Aiming at the characteristics and defects of electron beam welds, the TOFD inspection method of electron beam welds was developed, the basic principles of TOFD inspection were introduced in detail, the TOFD acoustic beam coverage was calculated, and the TOFD inspection of electron beam welds was carried out based on self-developed systems Experiment and analyze the experimental results. Experiments show that the ultrasonic TOFD detection method can quickly and accurately detect electron beam welds, which is an effective method for electron beam weld detection.

넓은 앙각 커버리지를 위한 3×4 재구성 급전회로를 갖는 5 GHz 무인항공기용 배열 안테나 설계

This paper presents a 5 GHz UAV array antenna with a 3×4 reconfigurable feeding network for wide elevation coverage. The proposed array comprises a four-element printed dipole antenna array in the top substrate, two supports with a tapered balun, a self-reflector for gain improvement, and a reconfigurable feeding network in the bottom substrate. For wide beam coverage, the feeding network comprises one RF switch, one Wilkinson power divider, and two 90° hybrid couplers; further, the network achieves wide beam coverage using one broadside beam and two end-fire beams. The measured impedance bandwidth, peak gain, and half-power beamwidth of the proposed array operated from 5.03 to 5.15 GHz are approximately 850 MHz(17 %), 6.7 dBi, and 180°, respectively.

Uniplanar High-Gain 2-D Scanning Leaky-Wave Multibeam Array Antenna at Fixed Frequency

A new topology for 2-D scanning multibeam array antenna (MAA) design is proposed. Different from the traditional 2-D scanning scheme, this new design approach is composed of a 1-D beam-forming network (BFN) and a set of 1-D pattern-reconfigurable antennas, which can together realize 2-D multibeam scanning. Compared with traditional schemes, the proposed topology has advantages of uniplanar configuration and better flexibility in scaling up the array. To demonstrate the validity of the proposed topology, a high-gain 2-D scanning leaky-wave MAA operating at 10 GHz is designed. A horn BFN and a fixed-frequency leaky-wave antenna (LWA) are designed as the feeding part and radiation part, respectively. A number of new techniques are also developed for the design. For the horn BFN, a new phase-compensation method to reduce the gain drop is presented and phase inverters are introduced to provide an extra 180° of phase shift. Meanwhile, some modification of the LWA is conducted for better compatibility between the horn BFN and the LWA. A substrate integrated waveguide (SIW) to half-mode SIW (HMSIW) transition is introduced between the horn BFN and the LWA. The LWAs are terminally shorted to avoid the usage of matched loads. The width of the LWA is investigated to achieve suitable beam coverage and S-parameters. Finally, the antenna is fabricated and experiments are conducted to verify the agreement between simulation and measurement.

Beam-Reconfigurable Multi-Antenna System with Beam-Combining Technology for UAV-to-Everything Communications

This paper proposes a beam-reconfigurable antenna for unmanned aerial vehicles (UAVs) with wide beam coverage by applying beam-combining technology to multiple antennas with different beam patterns. The proposed multi-antenna system consists of a circular patch antenna and a low-profile printed meandered monopole antenna. For beam combining, a coplanar waveguide with ground (CPW-G) structure feeding network is proposed, and it consists of two input ports, a 90° hybrid coupler, a microstrip 90° phase delay line, and a single-pole double-throw (SPDT) switch. It performs the role of power distribution and phase adjustment, and synthesizes the broad-side beam of the monopole antenna and the end-fire beam of the patch antenna to form the directive broadside beams in four different directions. The proposed antenna system operates at 5–5.5 GHz which covers both UAV ground control frequencies (5.03–5.09 GHz) and UAV mission frequencies (5.091–5.150 GHz). The peak gain, total efficiency, and half-power beamwidth (HPBW) of the antenna system are approximately 5.8 dBi, 76%, 145° in the elevation plane, and 360° in the azimuth plane respectively. Its electrical size and weight are λ 0 × λ 0 × 0.21 λ 0 at 5.09 GHz and 19.2 g, respectively.

A Dimension-Reduction Multibeam Antenna Scheme With Dual Integrated Butler Matrix Networks for Low-Complex Massive MIMO Systems

In this letter, a multiple-beam antenna (MBA) scheme with reduced port dimension is proposed for low-complex massive multiple-input–multiple-output (MIMO) systems. From practical scenario consideration, two 2-port and 8-element subarrays with dual 2-to-8 Butler matrix networks are designed for 3 dB beam coverage within 60° sector. Based on channel capacity analysis of an 8-subarray (8 × 8-element) antenna system, it is proved that only 25% number of radio frequency (RF) chains are utilized in the proposed scheme to achieve a competitive data transmission rate, compared with a regular 8 × 8-element and 64-chain massive MIMO system, with the advantages of low cost, low system weight, and low complexity of signal processing. The proposed 8-subarray system is built and measured to verify the antenna performance. The proposed multibeam antenna scheme exhibits potential possibilities in low-complex and low-cost massive MIMO systems for the fifth-generation (5G) applications.

A Metamaterial-Based $S/X$ -Band Shared-Aperture Phased-Array Antenna With Wide Beam Scanning Coverage

This article proposes an ultralow profile $S/X$ -band shared-aperture phased-array antenna (SAPAA), which can achieve wide beam scanning coverage in both the $S$ - and $X$ -bands. The SAPAA consists of an $S$ -band array with a triangular placement that has 11 elements and a grid array with $8\times 16\,\,X$ -band elements. To avoid grating lobes in wide beam scanning coverage, a metamaterial-based stacked mushroom structure is proposed to reduce the array spacing of the two bands, where an $X$ -band patch antenna is stacked on a traditional mushroom structure. A $4\times4$ subarray of the stacked mushroom structure operates as a single antenna element in $S$ -band. Consequently, each $S$ -band element corresponds to a $4\times4$ subarray of the $X$ -band element. Because a triangular arrangement in the $S$ -band array and a square arrangement in the $X$ -band array are employed, the array spacing of the two bands is $0.54\lambda _{\mathrm {L0}}$ and $0.51\lambda _{\mathrm {H0}}$ , respectively, which is suitable for wide beam scanning coverage. Moreover, the shorting pin of the mushroom structure is also the feeding pin of the $X$ -band patch. This structure reuse technology reduces the whole profile to less than $0.04\lambda _{0}$ . To verify this design, a prototype is fabricated through the multilayer printed circuit board process. It realizes ±50° beam coverage in both the $S$ - and $X$ -bands.

A Dual-Band Dual-Circularly Polarized Reflectarray for K/Ka-Band Space Applications

Reflectarrays (RAs) offer low-cost and low-profile solutions for reflector antennas that are polarization and frequency selective. These features augment their capabilities for point-to-point communications compared to conventional reflectors. Here, a dual-band dual-circularly polarized (CP) RA that can radiate independently shaped beams in the desired directions for each polarization in each band is proposed. The RA is composed of a dual-band dual-linearly polarized (LP) RA and a dual-band LP-to-CP polarizer. The proposed RA can be employed to reduce the number of the required apertures for a four-color multiple spot beam coverage implemented using a single-feed-per-beam configuration from four to two. The underlying unit cell of the proposed RA is designed for 18.3–18.8 GHz and 27.0–27.5 GHz. It provides a 323° phase shift in the lower band and 381° phase shift in the higher band while maintaining a cross-polarization level better than 15 dB in both bands and excellent decoupling between the two bands. An offset-fed RA is designed, fabricated, and measured.