Cylindrical Phased Array Research Articles

A Bendable Wideband Dual-Polarization Conformal Phased-Array Antenna

In this letter, we proposed a bendable wideband dual-polarization low-profile conformal phased array antenna. The antenna element is an Invert-F fed stacked-patch antenna. It provides an active VSWR < 3 for 10.7 GHz to 12.75 GHz in the principal planes. The proposed phased array antenna employs a row modular architecture, which enables it to bend to a cylindrical geometry. Both the antenna aperture and the active components of the conformal phased array antenna are considered for bending in the letter. A prototype conformal phased array antenna with 8 rows of 4 dual-polarization antenna element was fabricated, assembled and measured. Wide-angle beam scanning is achieved by electronically scanning along the curved axis of the cylindrical conformal phased array antenna. Moreover, there is no grating lobe when scanning down to 60°.

ОЦЕНКА ЭФФЕКТИВНОСТИ АСИМПТОТИЧЕСКОГО СООТВЕТСТВИЯ ДВУМЕРНЫХ И ТРЕХМЕРНЫХ ПРИКЛАДНЫХ ЗАДАЧ АНТЕННОЙ ТЕХНИКИ

Highlights the asymptotic correspondence of 2D and 3D electrodynamics problems using mathematical models to solve them. Includes criteria for practical using of asymptotic correspondence leads to efficiency of mathematical modeling. Mathematical models is based on integral equations to evaluate the interaction of antenna systems with closely placed scattering objects. Efficient numerical methods for solving systems of integral equations for E-polarization are proposed. A combined method for mathematical model development of a Vivaldi antenna using transition to two-dimensional problems is used. The results as a dynamic radiation patterns of a cylindrical phased antenna array with Vivaldi radiators are presented. Includes examples from practical antenna systems, highlighting the effectiveness of the mathematical models.

A Composite Right/Left-Handed Phase Shifter-Based Cylindrical Phased Array with Reinforced Particles Responsive to Magneto-Static Fields

A conformal cylindrical phased array antenna excited with composite right/left-handed (CRLH) phase shifters is proposed. The phase tuning of the CRLH phase shifter is achieved by embedding novel magneto-static field-responsive micron-sized particles in its structure. It is shown that through the tiny magnet activation of these novel magneto-static particles at appropriate locations along the length of CRLH stub and inter-digital fingers, variable phase shifts are obtained. The proposed particle-based CRLH phase shifter operates in C-band (5–6) GHz with a low insertion loss and phase error. The 1 × 4 cylindrical phased array is excited with the four unit cells of the proposed particle-embedded CRLH transmission line phase shifters to scan the main beam at desired scan angles. A prototype of a 1 × 4 cylindrical phased array excited with the particle-based CRLH phase shifters was fabricated, and the results show that the simulated results are in close agreement with the measured results. The conformal cylindrical array with the proposed particle-based CRLH phase shifters has great potential for use in printed and flexible electronics design where commercially available phase shifters have a definite drawback.

An endoluminal cylindrical sectored-ring ultrasound phased-array applicator for minimally-invasive therapeutic ultrasound.

The size of catheter-based ultrasound devices for delivering ultrasound energy to deep-seated tumors is constrained by the access pathway which limits their therapeutic capabilities. To devise and investigate a deployable applicator suitable for minimally-invasive delivery of therapeutic ultrasound, consisting of a 2D cylindrical sectored-ring ultrasound phased array, integrated within an expandable paraboloid-shaped balloon-based reflector. The balloon can be collapsed for compact delivery and expanded close to the target position to mimic a larger-diameter concentric-ring sector-vortex array for enhanced dynamic control of focal depth and volume. Acoustic and biothermal simulations were employed in 3D generalized homogeneous and patient-specific heterogeneous models, for three-phased array transducers with 32, 64, and 128 elements, composed of sectored 4, 8, and 16 tubular ring transducers, respectively. The applicator performance was characterized as a function of array configuration, focal depth, phasing modes, and balloon reflector geometry. A 16-element proof-of-concept phased array applicator assembly, consisting of four tubular transducers each divided into four sectors, was fabricated, and characterized with hydrophone measurements along and across the axis, and ablations in ex vivo tissue. Simulation results indicated that transducer arrays (1.5 MHz, 9mm OD × 20mm long), balloon sizes (41-50 mm expanded diameter, 20-60 mm focal depth), phasing mode (0-4) and sonication duration (30s) can produce spatially localized acoustic intensity focal patterns (focal length: 3-22 mm, focal width: 0.7-8.7 mm) and ablative thermal lesions (width: 2.7-16 mm, length: 6-46 mm) in pancreatic tissue across a 10-90 mm focal depth range. Patient-specific studies indicated that 0.1, 0.46, and 1.2cm3 volume of tumor can be ablated in the body of the pancreas for 120s sonications using a single axial focus (Mode 0), or four, and eight simultaneous foci in a toroidal pattern (Mode 2 and 4, respectively). Hydrophone measurements demonstrated good agreement with simulation. Experiments in which chicken meat was thermally ablated indicated that volumetric ablation can be produced using single or multiple foci. The results of this study demonstrated the feasibility of a novel compact ultrasound applicator design capable of focusing, deep penetration, electronic steering, and volumetric thermal ablation. The proposed applicator can be used for compact endoluminal or laparoscopic delivery of localized ultrasound energy to deep-seated targets.

Design of a Dual-Polarization Dipole Antenna for a Cylindrical Phased Array in Ku-Band

This paper proposes a dual-polarization dipole antenna for a cylindrical phased array working in Ku-band. The dipole antenna is double-layer structured and is composed of two orthogonal butterfly shaped dipole radiators, two ground co-planar waveguide (GCPW) feeding structures and vias. Each dipole is in the shape of a butterfly. The dipole patch is grooved triangularly and one side of it is bent into an N shape, which effectively expands the working frequency band of the antenna. The double-layer structure improves the isolation between the antenna ports. The antenna works between 15 GHz to 16.2 GHz and the isolation between the antenna’s two feeding ports in this band is better than 20 dB. The proposed dipole antenna is applied in a 32-element cylinder array. The simulation and measured results show that the array can scan between −60° to +60° in the azimuth plane with a gain fluctuation less than 2.5 dB. Therefore, the proposed design is an attractive candidate for conformal devices at Ku-band frequencies, and it also has a great potential for application in larger antenna arrays.

Measurement resolution of acoustic reflection imaging logging with a cylindrical phased array acoustic receiver station

Azimuthal acoustic reflection imaging logging plays an important role in the exploration and development of fracture-cavity reservoirs, because it can image geological structures within tens of meters around the borehole. However, minimal evaluations have been conducted for the detection of small-scale geological anomalies, particularly the simultaneous measurement of multiple small-scale scatterers. In this study, the scanning-reception implementations of phased array acoustic receiver stations in the Borehole Azimuthal Acoustic Reflection Imaging Tool (BAR) were developed based on the beamforming principle. The measurement responses of BAR were simulated and the scanning-reception performances of arcuate phased array (APA) and cylindrical phased array (CPA) acoustic receiver stations were compared using a three-dimensional (3D) finite difference algorithm for one or two small-scale caves in a formation away from a fluid-filled borehole. The azimuth and elevation measurement resolutions of CPA acoustic receiver stations were determined by analyzing the scattered wavefields under the circumstances of two caves on the same horizontal or vertical plane. Numerical simulation results showed that the echo waves scattered from small-scale caves were similar to those reflected by large-scale formation interfaces outside the borehole. The azimuth angle of a single cave could be obtained by calculating the amplitudes of P–P echoes at different azimuths received by the APA acoustic receiver station. Compared with the APA scanning-reception mode, the 3D scanning-reception mode based on the CPA acoustic receiver station was more applicable when two caves were simultaneously located outside the borehole. Under the calculation conditions of this study, the CPA acoustic receiver station had a limit azimuth resolution of ∼60°–90° and a limit elevation resolution of ∼8.8°–17.4° when two scatterers were located on the same horizontal or vertical plane. This work verified the superiority of the CPA scanning-reception mode for the detection of small-scale geological anomalies and provided a theoretical basis for the wider application of BAR.

Modular All-Metal Ultrawideband Cylindrical Array for Multifunction Operation

Legacy cylindrical phased array systems are constrained to narrowband operation due to antenna element limitations amid a growing need to support advanced multifunctional platform requirements. In this article, a notch-based all-metal ultrawideband (UWB) antenna element suitable for cylindrical arrays is introduced. The proposed element is designed to operate over 2.75–10 GHz while being highly amenable to a cylindrical architecture via modularized assembly of compact scalable column facets. The primary enabling technical innovations are: 1) a new shunt-loaded stepped-impedance (SI) gap design scheme to improve low-frequency performance without increasing profile and 2) the design of a tongue-and-groove azimuthal crosswall that precisely conforms to the wedge-shaped unit cell for simple yet robust cylinder assembly. For a proof-of-concept demonstration, a 120° sector array is built having a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$12^{\prime \prime }$ </tex-math></inline-formula> outer diameter and 21 columns—each comprising eight single-polarized elements (168 total feed points). Measurements are presented for active phase-mode impedance and embedded element patterns of a central element, demonstrating good agreement with full-wave simulations.

Simulation of the Sub-Wavelength Focusing Capability of Cylindrical Concave Phased Array

Simulation of the Sub-Wavelength Focusing Capability of Cylindrical Concave Phased Array

An Experimental Study on Phased Array Ultrasonic Testing for Internal Inspection of Gas Storage Wells

A reduction in wall thickness, caused by corrosion, of the inner and outer surfaces of underground compressed natural gas storage wells is one of the main causes of failure. Therefore, taking wall thickness measurements is an important task during periodic inspection. This study proposes a corrosion detection technique based on the well’s shape using cylindrical convex ultrasonic phased array and develops a cylindrical convex phased array probe with 512 elements. Using an example well of ∅177 × 10.36 mm, the influences of process parameters such as active aperture, focal length, gain, and gate threshold are studied. In addition, an experiment is conducted on a sample well with artificial defects for parameters optimization. Next, experimental tests are carried out on the well at the test platform according to the optimized parameters. The results show that the proposed technique is of high sensitivity and efficiency for the detection of corrosion defects and is able to detect pitting corrosion of more than ∅2 mm and line corrosion of 1 mm width.

Differences in Spectrum Width Estimates Between Electronic Scans and Mechanical Scans With a Phased Array Weather Radar

This letter presents differences in spectrum width estimates between electronic scans and mechanical scans with a cylindrical polarimetric phased array radar (CPPAR). Theoretical formulation of spectrum width estimates considering the transverse wind, shear, and turbulence within the radar&#x2019;s resolution volume is described. Cross correlation function between two resolution volumes is derived based on wave scattering by randomly distributed scatterers. Spectrum width estimates of ground clutter and weather scatterers with the CPPAR in electronic scans and mechanical scans are presented and compared. It is shown that instead of antenna rotation, the transverse wind, shear, and turbulence within the radar&#x2019;s resolution volume, which were previously ignored for narrow beams, contribute the most to the differences in spectrum width estimates between mechanical scans and electronic scans for the CPPAR with a wide beam.

Cylindrical phased array with adaptive nulling using eigen‐correlation technique

In this research work, eigen-correlation matrix based technique is developed for cylindrical antenna array to generate main beam and nulls simultaneously. The array complex weights (amplitude and phase) computed using the developed technique are used for single-beamforming, multi-beamforming, and beamforming with nulls steering simultaneously. The limitations of null steering range are investigated for different surface deformations of the cylindrical antenna array. The effects of surface deformations for different cylindrical radii on peak gain of main beam, half-power beamwidth, first-null beamwidth, and sidelobe level is also investigated. It is concluded that the developed eigen-correlation matrix based technique for cylindrical antenna array can be used for desired main beam generation and nulls steering simultaneously. The MATLAB, CST, and measurement validation of eight elements microstrip cylindrical phased array for single/multi-beams steering and adaptive nulling capability is demonstrated. This in turn makes the cylindrical phased array with adaptive nulling, a potential candidate suitable for use on fuselage portion of aircraft, airport surveillance radars, and mobile communication applications.

3D cone-beam breast ultrasonic tomography imaging for capacitive micromachined ultrasonic transducer cylindrical array.

In this paper, a 3D cone-beam ultrasonic transmission tomography method for capacitive micromachined ultrasonic transducer (CMUT) cylindrical phased array was proposed. The performance of the proposed method was evaluated by numerical simulation experiments. After beam focusing of the transmitting array, the deviation of reconstructed sound attenuation distribution and sound speed distribution were respectively reduced by at least 71.4% and 46.4%. The research results in this paper will provide a good theoretical and practical foundation for the realization of ultrasonic imaging based on CMUT cylindrical array in the future.

Design of a Cylindrical Crossed Dipole Phased Array Antenna for Weather Surveillance Radars

We present a cylindrical dual-polarization phased array antenna for weather surveillance radars that features high isolation, matched copolar beams, low sidelobe levels, and adaptive null steering. We present a crossed dipole antenna element to replace the patch antenna on the currently deployed cylindrical polarimetric phased array radar (CPPAR). The crossed dipole element offers suppressed surface wave and lower coupling between adjacent elements of an array. As a result, we achieved lower backlobe and sidelobe levels, and a higher match between copolar beams of CPPAR compared to the currently deployed multi-layer patch antenna. Further reduction of the sidelobe level and adaptive null steering are obtained using a modified particle swarm optimization. The proposed null steering mitigates the interference among the four concurrent beams of a cylindrical phased array radar. The improvement in CPPAR radiation characteristics has been verified by comparing the presented crossed dipole antenna’s radiation patterns and the existing aperture coupled patch antenna. The proposed crossed dipole phased array can benefit national weather radar networks to provide accurate multiparameter measurements enabling reliable observation of severe weather phenomena.

Mathematical modelling of the spatial excitation system of a cylindrical active phased antenna array with electronic commutation

This article discusses the excitation system of a cylindrical active phased antenna array with a spatial power supply system for the emitters. A brief historical comparison of the presented system with those based on the use of mechanical antenna rotation and a conformal phased antenna array with a matrix excitation system was performed. The advantages of an active phased antenna array with a spatial excitation system, its operational principles and the results of mathematical modelling are presented.

Initial Observations With Electronic and Mechanical Scans Using a Cylindrical Polarimetric Phased Array Radar

This letter presents initial weather measurements with a cylindrical polarimetric phased array radar (CPPAR) demonstrator developed at The University of Oklahoma. The overall system specifications, waveform design, beam pattern measurement, and beam-to-beam calibration of the CPPAR demonstrator are presented. The weather observations of convective precipitation are provided, employing a single-beam mechanical scan and commutating beam electronic scan. Measurement results from these two scan modes are compared, and the error statistics are derived and discussed. A new feature of the CPPAR commutating beam electronic scan in clutter detection is observed and explained.

Особенности динамических диаграмм направленности цилиндрических фазированных антенных решеток.

Особенности динамических диаграмм направленности цилиндрических фазированных антенных решеток.

3D‐MIMO beamforming realised by AQPSO algorithm for cylindrical conformal phased array

Three-dimensional (3D)-MIMO beamforming realised by adaptive quantum particle swarm optimisation (AQPSO) algorithm for the 36-element cylindrical conformal phased array is proposed in this study. The cylindrical conformal phased array consists of 36 circularly polarised microstrip antenna elements with ultra-wideband and high gain characteristics. The conformal array is divided into 12 subarrays using reconfigurable technology, and each subarray produces six beams to cover the corresponding spatial area. The 3D-MIMO beam is formed by AQPSO, and the active element pattern data of array elements is introduced to AQPSO to improve the accuracy of the algorithm. The simulated and measured results show that the cylindrical conformal phased array can achieve 3D-MIMO beam coverage from 0° to 360° in the azimuth plane and from 67.5° to 112.5° in the elevation plane. It can be applied for satellite communication and fifth-generation base station communication.

Numerical simulation of acoustic reflection logging while drilling based on a cylindrical phased array acoustic receiver station

With the increase of drilling activities, improving the azimuth measurement capability of acoustic logging while drilling (LWD) tools has been an urgent requirement for the petroleum exploration. In this study, a novel acoustic reflection LWD scheme is developed based on a cylindrical phased array (CPA) acoustic receiver station, which is composed of several arcuate phased array (APA) acoustic receiver stations arranged uniformly along the tool axis. The azimuthal performance of the APA and CPA acoustic receiver stations in acoustic reflection LWD with one or two formation interfaces away from the borehole are studied using the finite-difference time-domain method. The simulation results show that the amplitude distribution of reflected waves received by different azimuthal receiver elements is helpful for determining the azimuth angles of formation interfaces. Compared with the individual-reception mode, the azimuth measurement accuracy of the APA acoustic receiver station is greatly improved when working in the scanning-reception mode. Compared with the APA scanning-reception scheme, the CPA scanning-reception scheme performs better in simultaneously measuring the azimuth angles of two reflectors outside the borehole.

Deployable cylindrical phased-array applicator mimicking a concentric-ring configuration for minimally-invasive delivery of therapeutic ultrasound

A novel design for a deployable catheter-based ultrasound applicator for endoluminal and laparoscopic intervention is introduced. By combining a 1D cylindrical ring phased array with an expandable paraboloid or conical-shaped balloon-based reflector, the applicator can be controllably collapsed for compact delivery and deployed to mimic a forward-firing larger diameter concentric ring array with tight focusing and electronic steering capabilities in depth. Comprehensive acoustic and biothermal parametric studies were employed to characterize the capabilities of the applicator design as a function of transducer dimensions, phased array configuration, and balloon reflector geometry. Modeling results indicate that practical balloon sizes (43–57 mm expanded diameter), transducer array configurations (e.g. 1.5 MHz, 10 mm OD × 20 mm length, 8 or 16 array elements), and sonication durations (30 s) are capable of producing spatially-localized acoustic intensity focal patterns and ablative thermal lesions (width: 2.8–4.8 mm; length: 5.3–40.1 mm) in generalized soft tissue across a 5–100 mm depth range. Larger focal intensity gain magnitudes and narrower focal dimensions are attainable using paraboloid-shaped balloon reflectors with natural geometric focal depths of 25–55 mm, whereas conical-shaped reflectors (angled 45–55°) produce broader foci and extend electronic steering range in depth. A proof-of-concept phased array applicator assembly was fabricated and characterized using hydrophone and radiation force balance measurements and demonstrated good agreement with simulation. The results of this study suggest that combining small diameter cylindrical phased arrays with expandable balloon reflectors can enhance minimally invasive ultrasound-based intervention by augmenting achievable focal gains and penetration depths with dynamic adjustment of treatment depth.

Analysis of Scanning Characteristics in the H plane of Ultrabroadband Cylindrical Antenna Arrays of Biconical Elements

Finite-element method is used to construct electrodynamic models of cylindrical phased antenna arrays using bicones and fragments of bicones. Numerical experiments are used to study scanning characteristics of cylindrical phased antenna arrays with different numbers of biconical elements. Phase relationships of the elements are optimized for minimization of side lobes. It is shown that the ultrabroadband regime of the cylindrical phased antenna arrays can be implemented using circular scanning in the Н plane.