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Here, a wide‐angle phase‐frequency scanning linear array composed of leaky‐wave antennas (LWAs) is proposed. The unit cell of the proposed LWA element consists of microstrip lines and grounded vias. By increasing the scanning rate based on theoretical analysis, wide scanning range with low gain fluctuation of the LWA element is achieved. For gain enhancement, the LWAs are arranged along their length to form a linear array. A method combining theoretical derivation and numerical calculation is used to obtain a high efficiency and low sidelobe level (SLL) of the array. To verify the design method, a 1×4 $1\times 4$ linear LWA array is designed, fabricated and measured. The main beam of the LWA array can scan from −60° $-60^\circ $ to 50° $50^\circ $ in frequency band of 9.3–11.6 GHz with gain fluctuation less than 2 dB and SLL less than −9 $-9$ dB. The measured results are in good agreement with the simulated results. [ABSTRACT FROM AUTHOR]

Photoacoustic imaging (PAI) is a rapidly developing biomedical imaging technology. Linear array-based photoacoustic tomography (LA-PAT) is one of the most popular configurations of cross-sectional PAI due to its simplicity and clinical translatability. However, when using an optical fiber for LA-PAT, the optical beam shape is deformed due to rapid divergence and, therefore, a larger area on the tissue is illuminated (and the illumination across the linear array is non-uniform), leading to the acquisition of PA signals outside the desired cross-section, which generates artifacts and degrades image resolution. A Powell lens is an optical element that converts a circular beam profile to a nearly linear flat-top profile. In this paper, a Powell lens is used to generate a uniform line illumination scheme that is evaluated with Zemax OpticStudio 2023 R1.02. The system is then characterized experimentally, and the performance is compared with a conventional illumination scheme in LA-PAT. [ABSTRACT FROM AUTHOR]

The advancement of future technology seeks to create wireless systems capable of achieving faster data transfer rates. One solution to confront this challenge is by employing Multiple-Input Multiple-Output (MIMO) systems. Nonetheless, the primary obstacle in assessing MIMO performance revolves around the size and spacing of the antennas to maintain isolation among the ports. Consequently, it is essential to devise an approach to tackle these challenges, with the utilization of a DGS as a viable and promising approach. Hence, in this study, we developed a dual-frequency MIMO system featuring two linear array antennas with two elements each and configured to function at 128 GHz and 178 GHz. Initially, this design is conceived as a single-element structure before evolving into a two-element MIMO antenna array configuration. The antenna's physical dimensions are 2.7 × 3.65 × 0.15 mm3, and it consists of two linear array nodes positioned at a separation distance of 0.18 mm. Additionally, the antenna delivers peak gains of 5.16 dB and 6.24 dB at frequencies of 128 GHz and 178 GHz, respectively. The values of various MIMO performance indicators meet stringent standards with ECC values below 0.012 and a DG of approximately 10 dB. Furthermore, the TARC remains below 0 dB. The aim of this research is to create a novel design for a THz antenna that can achieve a wide bandwidth and a high gain while maintaining the standard compact antenna size necessary for THz applications.

The power-weighted distribution method is used to satisfy radiation pattern requirements at a certain targeted sidelobe level (SLL) suppression. This article reports a detailed discussion of theoretical and experimental approaches for the application of the Kaiser function in power-weighted linear array prototypes. An exploration of the design and realization of a Kaiser function-based linear array was presented. Furthermore, performance evaluations were performed for several important factors in the Kaiser function-based linear array configuration. The performance evaluations include feeding network variations, number of element (N) variations, and inter-element distance (d) variations. The prototype of Kaiser function-based linear array was configured by a serial feeding type on the folded structure of a proximity-coupled feeding network. The Kaiser function parameter, $\beta $ , is used to determine the set of weighting coefficients. In the application of $\beta $ value of 2, the SLL suppression is 34.63 dB – 34.78 dB for simulation result, and 27.96 dB – 33.47 dB for measurement result. A performance comparison with a uniform linear array and a Chebyshev function-based linear array in an equal configuration is also shown. The Kaiser function utilization as a weighting coefficient in a linear array design shows a significant increase of 20 dB – 30 dB in SLL suppression compared to the one with a uniform distribution, and 5 dB – 8 dB in SLL suppression compared to the Chebyshev function-based linear array. The implementation of the power-weighted distribution method with Kaiser functions resulted in good results for the development of more complex designs with a larger number of antenna array elements.

With the increase in demand for high data rates and high bandwidth because of multiple users all over the globe, the technology has moved toward the next-generation of wireless communication. This rapid advancement of wireless communication technologies has led to the emergence of 5G networks, which promise significantly higher data rates, lower latency, and enhanced connectivity. Researchers believe that five essential techniques can enable 5G. Beamforming is one of those essentials, as it plays a vital role in achieving reliable and high-capacity communication. This review article portrays a comprehensive analysis of the 5G beam-former Microstrip Patch Antenna array techniques for communication systems. The paper comprises of a deep overview of the fundamental concepts and principles of beamforming, including analog, hybrid, and digital beamforming techniques. It explores the advantages and disadvantages of each approach and discusses their suitability for 5G applications. An in-depth examination of various beamforming techniques employed in 5G, encompassing traditional beamforming, massive Multiple- Input-Multiple-Output beamforming, hybrid beamforming, and adaptive beamforming. The discussion encompasses the strengths, weaknesses, and performance trade-offs of each technique, along with their applicability in diverse deployment scenarios and applications. The review of multiple couplers that are used for the feeding of the antenna is discussed with included hybrid coupler, Wilkinson power divider, branch line coupler, and butler matrix in beamformer smart antenna for 5G/6G communications. Numerous beamforming techniques are compared based on their merits, demerits, and applications. Moreover, the dielectric substrate utilized to design the beamformer was also reviewed. The findings presented in this paper serve as a valuable resource for the researcher, scholars, and engineers working in the field of 5G wireless communications and antenna designing, facilitating the development and deployment of efficient and robust beamforming solutions for future 5G networks. [ABSTRACT FROM AUTHOR]

With the increase in demand for high data rates and high bandwidth because of multiple users all over the globe, the technology has moved toward the next-generation of wireless communication. This rapid advancement of wireless communication technologies has led to the emergence of 5G networks, which promise significantly higher data rates, lower latency, and enhanced connectivity. Researchers believe that five essential techniques can enable 5G. Beamforming is one of those essentials, as it plays a vital role in achieving reliable and high-capacity communication. This review article portrays a comprehensive analysis of the 5G beamformer Microstrip Patch Antenna array techniques for communication systems. The paper comprises of a deep overview of the fundamental concepts and principles of beamforming, including analog, hybrid, and digital beamforming techniques. It explores the advantages and disadvantages of each approach and discusses their suitability for 5G applications. An in-depth examination of various beamforming techniques employed in 5G, encompassing traditional beamforming, massive Multiple-Input-Multiple-Output beamforming, hybrid beamforming, and adaptive beamforming. The discussion encompasses the strengths, weaknesses, and performance trade-offs of each technique, along with their applicability in diverse deployment scenarios and applications. The review of multiple couplers that are used for the feeding of the antenna is discussed with included hybrid coupler, Wilkinson power divider, branch line coupler, and butler matrix in beamformer smart antenna for 5G/6G communications. Numerous beamforming techniques are compared based on their merits, demerits, and applications. Moreover, the dielectric substrate utilized to design the beamformer was also reviewed. The findings presented in this paper serve as a valuable resource for the researcher, scholars, and engineers working in the field of 5G wireless communications and antenna designing, facilitating the development and deployment of efficient and robust beamforming solutions for future 5G networks.

We consider a three-dimensional antenna system modeled by a linear array, which focuses radiation in the far-field zone. The system is formed by semitransparent plane mirrors inclined to the vertical axis. The geometry of the system satisfies quasioptical conditions. The distance between separate elements of the system corresponds to the conditions of the Fresnel zone, and the radiation pattern of the system is found in its far-field zone. The possibility of separation of the variables is expected in the apertures of different elements and in the components of the radiation pattern. We obtain explicit formulas for the values of the fields in the constituent elements of the antenna and of the created radiation pattern. The ability of the system to form radiation patterns of different shapes is confirmed by numerical results. [ABSTRACT FROM AUTHOR]

A comprehensive analysis on performance of Dolph-Tschebyscheff distribution for different array length and side lobe levels has been presented in this paper. Dolph-Tschebyscheff array, which is a compromise between binomial and uniform array, produces optimum side lobe level, efficiency, and half power beamwidth, hence, it is referred to as optimum distribution. For a larger number of elements, the Tschebyscheff array demands higher side lobe suppression in order to avoid the abrupt amplitude distribution at the edges that results from more elements and lower side lobe suppression, at the same time, higher side lobe suppression decreases aperture efficiency and gain. These novel analyses have been carried out by computing parameters such as power pattern, first side lobe level, directivity and half power beamwidth. Plots for optimum SLL and critical SLL are derived for a range of array elements, which defines three regions assisting in selection of appropriate number of elements and desired major-to-minor lobe levels for linear/planar array antenna designs. Practical array analysis is proposed by approximating the amplitude of arrays' end elements, whenever it becomes higher than their adjacent elements. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Geodesy & Geodynamics (1671-5942) is the property of Editorial Board Journal of Geodesy & Geodynamics and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this article, we propose a light weight, low profile Multiple Input Multiple Output (MIMO) antenna system for compact 5th Generation (5G) mmwave devices. Using a RO5880 substrate that is incredibly thin, the suggested antenna is made up of circular rings stacked vertically and horizontally on top of one another. The single element antenna board has dimensions of 12 × 12 × 0.254 mm 3 while the size of the radiating element is 6 × 2 × 0.254 mm 3 (0.56 λ 0 × 0.19 λ 0 × 0.02 λ 0 ). The proposed antenna showed dual band characteristics. The first resonance showed a bandwidth of 10 GHz with a starting frequency of 23 GHz to an ending frequency point of 33 GHz followed by a second resonance bandwidth of 3.25 GHz ranging from 37.75 to 41 GHz, respectively. The proposed antenna is transformed into a four element Linear array system with size of 48 × 12 × 0.254 mm 3 (4.48 λ 0 × 1.12 λ 0 × 0.02 λ 0 ). The isolation levels at both resonance bands were noted to be >20 dB which shows high levels of isolation among radiating elements. The MIMO parameters such as Envelope Correlation Co-efficient (ECC), Mean Effective Gain (MEG) and Diversity Gain (DG) were derived and were found to be in satisfactory limits. The proposed MIMO system model is fabricated and through validation and testing of the prototype, the results were found to be in good agreement with simulations. [ABSTRACT FROM AUTHOR]

Photoacoustic imaging (PAI) is a rapidly developing biomedical imaging technology. Linear array-based photoacoustic tomography (LA-PAT) is one of the most popular configurations of cross-sectional PAI due to its simplicity and clinical translatability. However, when using an optical fiber for LA-PAT, the optical beam shape is deformed due to rapid divergence and, therefore, a larger area on the tissue is illuminated (and the illumination across the linear array is non-uniform), leading to the acquisition of PA signals outside the desired cross-section, which generates artifacts and degrades image resolution. A Powell lens is an optical element that converts a circular beam profile to a nearly linear flat-top profile. In this paper, a Powell lens is used to generate a uniform line illumination scheme that is evaluated with Zemax OpticStudio 2023 R1.02. The system is then characterized experimentally, and the performance is compared with a conventional illumination scheme in LA-PAT.

Australia's cervical screening program transitioned from cytology to HPV-testing with genotyping for HPV16/18 in Dec’2017. We investigated whether program data could be used to monitor HPV vaccination program impact (commenced in 2007) on HPV16/18 prevalence and compared estimates with pre-vaccination benchmark prevalence. Pre-vaccination samples (2005–2008) (n = 1933; WHINURS), from 25 to 64-year-old women had been previously analysed with Linear Array (LA). Post-vaccination samples (2013-2014) (n = 2989; Compass pilot), from 25 to 64-year-old women, were analysed by cobas 4800 (cobas), and by LA for historical comparability. Age standardised pre-vaccination HPV16/18 prevalence was 4.85% (95%CI:3.81–5.89) by LA; post-vaccination estimates were 1.67% (95%CI:1.21–2.13%) by LA, 1.49% (95%CI:1.05–1.93%) by cobas, and 1.63% (95%CI:1.17–2.08%) for cobas and LA testing of non-16/18 cobas positives (cobas/LA). Age-standardised pre-vaccination oncogenic HPV prevalence was 15.70% (95%CI:13.79–17.60%) by LA; post-vaccination estimates were 9.06% (95%CI:8.02–10.09%) by LA, 8.47% (95%CI:7.47–9.47%) by cobas and cobas/LA. Standardised rate ratios between post-vs. pre-vaccination rates were significantly different for HPV16/18, non-16/18 HPV and oncogenic HPV: 0.34 (95%CI:0.23–0.50), 0.68 (95%CI:0.55–0.84) and 0.58 (95%CI:0.48–0.69), respectively. Additional strategies (LA for all cobas positives; combined cobas and LA results on all samples) had similar results. If a single method is applied consistently, it will provide important data on relative changes in HPV prevalence following vaccination.

Manipulating radiation patterns is challenging, especially at low frequencies. In this paper, we demonstrate that acoustic metamaterials arranged as an array of quadrupoles remarkably improve the directionality of acoustic radiation at low frequencies, compared with previous metamaterials arranged as monopole and dipole structures. The directivity of the acoustic radiation can be adjusted by changing the characteristic parameter and the symmetry of the structure, which provides a flexible method of adjusting radiation directions. The directionality can be further improved by constructing a linear array. Our work establishes acoustic radiation control via quadrupolar metamaterials. [ABSTRACT FROM AUTHOR]

The folded hypercube is one of the hypercube variants and is of great significance in the study of interconnection networks. In a folded hypercube, information can be broadcast using efficient distributed algorithms. In the context of parallel computing, folded hypercube has been studied as a possible network topology as an alternative to the hypercube. The routing and wavelength assignment (RWA) problem is significant, since it improves the performance of wavelength-routed all-optical networks constructed using wavelength division multiplexing approach. Given the physical network topology, the aim of the RWA problem is to establish routes for the connection requests and assign the fewest possible wavelengths in accordance with the wavelength continuity and distinct wavelength constraints. This paper discusses the RWA problem in a linear array for the folded hypercube communication pattern by using the congestion technique. • Study of the routing and wavelength assignment problem. • Guest graph is the folded hypercube communication pattern. • Host graph is a linear array wavelength division multiplexing optical network. • Congestion calculation by an embedding scheme and maximum induced subgraph problem. • Estimation of optimal number of wavelengths using congestion technique. [ABSTRACT FROM AUTHOR]

In practice, random errors in the excitations (amplitude and phase) of array elements cause undesired variations in the array patterns. In this paper, the clustered array elements with tapered amplitude excitations technique are introduced to reduce the impact of random weight errors and recover the desired patterns. The most beneficial feature of the suggested method is that it can be used in the design stage to count for any amplitude errors instantly. The cost function of the optimizer used is restricted to avoid any unwanted rises in sidelobe levels caused by unexpected perturbation errors. Furthermore, errors on element amplitude excitations are assumed to occur either randomly or sectionally (i.e., an error affecting only a subset of the array elements) through the entire array aperture. The validity of the proposed approach is entirely supported by simulation studies.

Multiple-input-multiple-output (MIMO) optical wireless communication systems are potential candidates for high-speed data transmission in indoor environments. In this work, we present an experimental evaluation of two different MIMO systems, i.e., conventional-MIMO (c-MIMO) and imaging-MIMO (i-MIMO) in terms of design considerations. Both systems use the same transmitter configuration featuring a one-dimensional (light-emitting diode) LED transmitting array. On the receiver side, the c-MIMO system employs a similar one-dimensional receiving avalanche photodetector (APD)-based array, whereas the i-MIMO system uses a customized imaging camera-based receiver design. To assess the performance of the two systems, the channel matrix and the bit-error rate are calculated based on the experimental data. At distances shorter than 50 m, the proposed c-MIMO system demonstrates a good transmission performance, particularly when the maximum likelihood detection (MLD) technique is applied. Whereas, at long distances ranging from 40 m to 65 m, the proposed i-MIMO system can ensure an error-free transmission due to the efficient spatial separation between the emitted optical beams. Furthermore, the experimental results confirm that our systems have the potential for high data rates over longer distances in indoor environments.

This paper presents a new scheme of applying CORPS (coherently radiating periodic structures) for reducing the number of phase shifters in linear antenna arrays. This scheme can be seen as a combination of the properties of two techniques: CORPS and butler. The proposed system applies an interleaving of several blocks of 2 × 3 CORPS networks. This interleaving of two stages of 2 × 3 CORPS networks is made in a convenient way to provide the required progressive phase for beam-scanning and the level of amplitude excitations necessary for achieving the radiation characteristics of low SLL. Interesting results are provided based on experimental measurements and full-wave simulations to analyze and evaluate the performance of the feeding network based on CORPS and the reduction capability of the number of phase shifters in the antenna system. The proposed design methodology achieves a reduction capability of 66% in the number of phase shifters used in linear antenna arrays. This reduction in the complexity of the antenna system is reached maintaining a peak SLL of −22 dB with scanning ranges of until ±25°. A good design option is provided to simplify the complexity of the feeding network in antenna array applications. [ABSTRACT FROM AUTHOR]

An effective method is proposed to excite the untilted edge slot antennas. In the proposed method, two T-shaped wires are placed at both sides of each untilted slot. Two legs of each T-shaped wire are connected to the waveguide walls, while the third leg is open. One of the T-shaped wires connects the upper broad wall of the waveguide to the narrow wall of the waveguide which contains the slots. Similarly, the other T-shaped wires connect the lower broad wall of the waveguide to the narrow wall of the waveguide that contains the slots. The phase reversal between the adjacent slots can be accomplished by changing the orientation of the T-shaped wires. It is shown that the arm lengths of the connected wires can be employed as a parameter to control the radiated power by the slots. Furthermore, the arm lengths of the open wires can be selected properly to control the dynamic range of the equivalent normalized susceptance associated with each untilted slot antenna. To validate the effectiveness of the proposed antennas, two linear arrays consisting of 11 slots have been designed, implemented, and tested. The simulation and the measurement results of the designed arrays show that for the proposed untilted edge slot antennas, the dynamic range of the equivalent normalized susceptance is improved significantly which leads to a straightforward design process with no requirement to resort to any time-consuming tuning process. [ABSTRACT FROM AUTHOR]

Multiple-input-multiple-output (MIMO) optical wireless communication systems are potential candidates for high-speed data transmission in indoor environments. In this work, we present an experimental evaluation of two different MIMO systems, i.e., conventional-MIMO (c-MIMO) and imaging-MIMO (i-MIMO) in terms of design considerations. Both systems use the same transmitter configuration featuring a one-dimensional (light-emitting diode) LED transmitting array. On the receiver side, the c-MIMO system employs a similar one-dimensional receiving avalanche photodetector (APD)-based array, whereas the i-MIMO system uses a customized imaging camera-based receiver design. To assess the performance of the two systems, the channel matrix and the bit-error rate are calculated based on the experimental data. At distances shorter than 50 m, the proposed c-MIMO system demonstrates a good transmission performance, particularly when the maximum likelihood detection (MLD) technique is applied. Whereas, at long distances ranging from 40 m to 65 m, the proposed i-MIMO system can ensure an error-free transmission due to the efficient spatial separation between the emitted optical beams. Furthermore, the experimental results confirm that our systems have the potential for high data rates over longer distances in indoor environments. [ABSTRACT FROM AUTHOR]

Copyright of Advanced Textile Technology is the property of Zhejiang Sci-Tech University Magazines and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A technique to perform the synthesis of sum patterns which can achieve beam shaping using individual heights of side lobes is presented. The side lobes can be adjusted to any arbitrary specification, and flat-top far-field radiation patterns are generated using enhanced flower pollination algorithm (EFPA) which is discussed in this paper. The problem of designing an array can be expressed as an optimization problem that aims to reduce the first two side lobes to − 50 dB and by reducing the remaining side lobes to − 40 dB in case 1. The EFPA is applied to determine the excitation coefficients of their amplitudes so as to obtain the required pattern. The objective for case 2 is to obtain the flat-top sector beam for specified angular regions. Complex excitation coefficients are determined using EFPA for various beam widths. The radiation patterns are generated numerically using the obtained excitation coefficients. The results reveal that not only the ripples are controlled in the trade-in region, but the side lobe levels are also maintained in the acceptable limits. The results presented are very much useful for marine radar applications. [ABSTRACT FROM AUTHOR]

Angle-based localization of a source at unique coordinates in the three-dimensional (3-D) space utilizes traditionally the two-dimensional (2-D) angle of arrival (AOA) measurements from planar arrays. This paper investigates the positioning performance and develops an optimal solution for the 3-D localization using one-dimensional (1-D) space angle (SA) measurements that has the appeal of involving linear arrays only. The localization performance by SA is less understood and the positioning algorithms from the literature are suboptimal and have restrictions on the altitudes and orientations of the linear array receivers. This paper establishes the basic concept of using SA for localization, and conducts analytical comparison of SA and AOA positionings by cross arrays, where the contrasts in the angle observation accuracy, the geometric dilution effect and overall localization performance are elaborated. A solution that can reach the Cramér-Rao Lower Bound performance under Gaussian noise is also proposed that does not have restriction on the placement of the linear array receivers. It consists of an initial solution by semidefinite relaxation and a refined solution by an algebraic estimator. Simulations validate the theoretical investigation and the algorithm performance. [ABSTRACT FROM AUTHOR]

In adaptive beamforming by compact arrays, the excitation amplitude and phase of each array element require dynamic optimization for controlling the radiation pattern at different angular sectors. If the objective function of adaptive beamformer is defined by some properties other than the deterministic properties of arrays such as directivity or signal-to-noise ratio, evolutionary optimization is advantageously implemented to minimize the objective function. Nevertheless, the convergence time of most of the evolutionary optimization methods exponentially increases by the number of array elements $N$. For large $N$ , the above convergence issue slows down the beamforming agility. To improve the above inefficiency, we first express the array factor by a Schelkunoff polynomial of order $N - 1$. Second, a discrete optimization method like genetic algorithm optimally factorizes the polynomial into two polynomials of orders $N - 1 - P$ and $P$ , where $N - 1 - P \ge P$. Third, the locations of zeros of these polynomials are optimized across the visible region by a continuous optimization method like particle swarm optimization to attain the desired objective function. When these two polynomials are multiplied, the resultant polynomial of order $N - 1$ demonstrates improved features with respect to the original polynomial of order $N - 1$ in sensitivity, sidelobe level, and convergence. Representative examples include airborne radars. [ABSTRACT FROM AUTHOR]

This paper presents a planar multi-circular loop antenna with a wide impedance bandwidth for next generation mm-wave systems. The proposed antenna comprises three circular rings with a partial ground plane with a square slot. The resonating structure is designed on a 0.254 mm thin RO5880 substrate with a relative permittivity of 2.3. The single element of the proposed design showed a resonance response from 26.5 to 41 GHz, with a peak gain of 4 dBi and radiation efficiency of 96%. The proposed multicircular ring antenna element is transformed into a four-element array system. The array size is kept at 18.25 × 12.5 × 0.254 mm3 with a peak gain of 11 dBi. The antenna array is fabricated and measured using the in-house facility. The simulated and measured results are well agreed upon and are found to be suitable for mm-wave communication systems. [ABSTRACT FROM AUTHOR]

This work uses the active and parasitic components in a linear antenna array composed of parallel dipoles to synthesize a cosecant squared pattern using the Quantum Particle Swarm Optimization approach. This pattern is obtained by the mechanical displacement of the parasitic array of the parallel dipole placed in front of an active dipole array. In addition to it, mutual coupling between the antenna elements is considered in this process. Two examples are presented to visualize the effect of this approach in the synthesis process. Moreover, obtained results from the simulation are also validated by the results produced from FEKO software. [ABSTRACT FROM AUTHOR]

In this article, a novel beam shaping technique is developed to synthesize the array factor (AF) radiation pattern of linear and planar antenna arrays. The proposed method is established based on the expanding of AF using Legendre transform in conjunction with an integrand operator. A system of linear equations is derived and its solution is obtained using least-square method (LSM) for the required pattern. In addition, an iterative procedure is introduced to reduce the number of elements of the primary designed array for a specified mean square error (mse). Then, the proposed method is applied to synthesize the AF of planar and ring antenna arrays. To verify the performance of the proposed method, a few comprehensive well-known linear, planar, and ring arrays are examined. The obtained results show that the introduced method can be used to design the AF pattern of many types of practical arrays with good accuracy. [ABSTRACT FROM AUTHOR]

An elevation and azimuth direction-finding (DF) method is presented by introducing the pattern reconfigurable antenna (PRA) into a two-element array. An equivalent multidimensional array is built by the two-element PRA array with switchable beams of same or opposite directions. With the introduction of same- and opposite-direction modes of PRAs, the elevation and azimuth angles are estimated by the methods of time-modulated array (TMA) and amplitude comparison, respectively. Meanwhile, a 2-D lookup table is built to correct the coning-error effect of the amplitude comparison. Compared with the conventional 2-D DF method with two orthogonal linear arrays, only a single linear array with not less than two elements is needed in the proposed method. Hence, it has the advantages of simple structure, compact size, and low cost. Simulated results are provided to verify the proposed 2-D DF method, and an S-band two-element PRA array is constructed to demonstrate its experimental feasibility. [ABSTRACT FROM AUTHOR]

The exchanged folded hyerpcube is a brand-new interconnection network proposed by Qi et al. This paper considers the case such that n = 1 + s + t, and the exchanged folded hypercube is denoted by EFH(s, t). The bus topology is one of the most well-known topologies in WDM optical networks. A bus-topology WDM optical network with N terminals can be described by a linear array graph Ln, where N = 2n. In this article, the routing and wavelength allotment problem for embedding EFH(s, t) communication pattern on Ln is studied. To address this problem, the author proposed an embedding scheme as well as a wavelength allotment algorithm. Moreover, the number of allotted wavelengths is shown to be 2s+t + 2s+t− 2 + ⌊2t/3⌋. [ABSTRACT FROM AUTHOR]

Ultrasound (US) is an attractive modality for wireless power transfer (WPT) to biomedical implants with millimeter (mm) dimensions. To compensate for misalignments in WPT to a mm-sized implant (or powering a network of mm-sized implants), a US transducer array should electronically be driven in a beamforming fashion (known as US phased array) to steer focused US beams at different locations. This paper presents the theory and design methodology of US WPT links with phased arrays and mm-sized receivers (Rx). For given constraints imposed by the application and fabrication, such as load (RL) and focal distance (F), the optimal geometries of a US phased array and Rx transducer, as well as the optimal operation frequency (fc) are found through an iterative design procedure to maximize the power transfer efficiency (PTE). An optimal figure of merit (FoM) related to PTE is proposed to simplify the US array design. A design example of a US link is presented and optimized for WPT to a mm-sized Rx with a linear array. In measurements, the fabricated 16-element array (10.9×9×1.7 mm3) driven by 100 V pulses at fc of 1.1 MHz with optimal delays for focusing at F = 20 mm generated a US beam with a pressure output of 0.8 MPa. The link could deliver up to 6 mW to a ∼ 1 mm3 Rx with a PTE of 0.14% (RL = 850 Ω). The beam steering capability of the array at -45o to 45o angles was also characterized. [ABSTRACT FROM AUTHOR]

This article presents an innovative design technique for feeding phase antenna arrays using coherently radiating periodic structure (CORPS) technology for reducing the number of phase shifters (PSs) in limited-scan applications with low sidelobe level (SLL). The proposed configuration is implemented taking advantage of the phase interpolation property of a CORPS network of one layer. This configuration is built by interconnecting $2\times 3$ CORPS networks in a strategic way in order to provide a reduction in the number of PSs while maintaining the scanning capability. Experimental results and full-wave simulations based on CST Microwave Studio reveal that the proposed design technique reduces the recombination losses and generates a better phase slope with respect to the basic CORPS network providing a reduction in the number of PSs. As a novel contribution, this article provides the full antenna system design in order to analyze and study the PSs reduction performance and scanning capabilities of the proposed technique to feed linear antenna arrays. The proposed design technique provides a reduction in the number of PSs for a scanning range of ±25° in linear arrays. The array design model includes the application of the raised cosine amplitude distribution to generate a radiation pattern with minimum SLL. The linear array system was validated by experimental measurements of the full system prototype and full-wave simulations results are provided to verify the accuracy of the array model and to take mutual coupling into account. The proposed case provides a good design compromise with respect to other cases in the state of the art. [ABSTRACT FROM AUTHOR]

In practice, random errors in the excitations (amplitude and phase) of array elements cause undesired variations in the array patterns. In this paper, the clustered array elements with tapered amplitude excitations technique are introduced to reduce the impact of random weight errors and recover the desired patterns. The most beneficial feature of the suggested method is that it can be used in the design stage to count for any amplitude errors instantly. The cost function of the optimizer used is restricted to avoid any unwanted rises in sidelobe levels caused by unexpected perturbation errors. Furthermore, errors on element amplitude excitations are assumed to occur either randomly or sectionally (i.e., an error affecting only a subset of the array elements) through the entire array aperture. The validity of the proposed approach is entirely supported by simulation studies. [ABSTRACT FROM AUTHOR]

To accurately detect objects, the radar antenna must have a high gain for the desired range. The antenna uses an array method to increase the gain. It has a unidirectional radiation pattern to meet the X-band radar implementation as a ship navigation tool. The X-band radar works at high frequencies. Thus, it will be more sensitive in detecting small particles, including rain particles. The use of a mitered-bends feeding network method by cutting the 90-degree curve is to maximize the power transmitted to reduce losses. This method spreads the bandwidth of the antenna. The antenna is designed and fabricated into a linear array of 8 elements, using the R04003C Rogers substrate with a microstrip line supply. This study limits up to 8 elements of radiation, followed by the addition of a method to expand the bandwidth of antennas. Considering material limitation and duration of antenna design. The final antenna dimensions are 142.40 mm × 42.8 mm. The measuring results show fc = 9.496 GHz, S11 = -32.64 dB, VSWR 1.05, bandwidth = 41.9 MHz (9.5159 GHz - 9.4740 GHz), and gain 8.8 dB as well as a linear polarized antenna with unidirectional pattern direction. The radar antenna tends to have a narrow beamwidth and high gain.

In this article, we propose a light weight, low profile Multiple Input Multiple Output (MIMO) antenna system for compact 5th Generation (5G) mmwave devices. Using a RO5880 substrate that is incredibly thin, the suggested antenna is made up of circular rings stacked vertically and horizontally on top of one another. The single element antenna board has dimensions of 12 × 12 × 0.254 mm3 while the size of the radiating element is 6 × 2 × 0.254 mm3 (0.56λ0 × 0.19λ0 × 0.02λ0). The proposed antenna showed dual band characteristics. The first resonance showed a bandwidth of 10 GHz with a starting frequency of 23 GHz to an ending frequency point of 33 GHz followed by a second resonance bandwidth of 3.25 GHz ranging from 37.75 to 41 GHz, respectively. The proposed antenna is transformed into a four element Linear array system with size of 48 × 12 × 0.254 mm3 (4.48λ0 × 1.12λ0 × 0.02λ0). The isolation levels at both resonance bands were noted to be >20 dB which shows high levels of isolation among radiating elements. The MIMO parameters such as Envelope Correlation Co-efficient (ECC), Mean Effective Gain (MEG) and Diversity Gain (DG) were derived and were found to be in satisfactory limits. The proposed MIMO system model is fabricated and through validation and testing of the prototype, the results were found to be in good agreement with simulations.

Manipulating radiation patterns is challenging, especially at low frequencies. In this paper, we demonstrate that acoustic metamaterials arranged as an array of quadrupoles remarkably improve the directionality of acoustic radiation at low frequencies, compared with previous metamaterials arranged as monopole and dipole structures. The directivity of the acoustic radiation can be adjusted by changing the characteristic parameter and the symmetry of the structure, which provides a flexible method of adjusting radiation directions. The directionality can be further improved by constructing a linear array. Our work establishes acoustic radiation control via quadrupolar metamaterials.

This paper addresses a mathematical formulation to determine the radiation performance of an acoustic beamforming array, which is valid for both near-field and far-field regions. The developed beamforming analysis is generic for application to any array configuration, with the array elements having a radiating aperture of canonical contours. The beamforming analysis presented in this paper for the acoustic transducer array is obtained by the process of vector summation of radiated fields from the elements of the acoustic transducer array with an array factor and beam steering phase factor. The initial validity of the beamforming analysis is examined by considering the far-field region as a particular case of the near-field region with the relevant distance criterion. The numerous simulation studies presented in this paper show that the proposed method produces excellent results with the distinct structure of sidelobes at a distance RNF ≥ 0.5D²/λ from the acoustic aperture of (7 x 1) linear and (7 x 7) planar array of acoustic transducers. If the distance between the transducer array and the point of observation is very low (RNF < 0.5D²/λ), simulation results indicate a less directive main beam. The two-dimensional near field beam steering method proposed in this paper finds the significant utility in many practical applications such as Underwater Acoustic Imaging (UAI) systems and Underwater Acoustic Communication (UAC). [ABSTRACT FROM AUTHOR]

Goafs are one of the main factors that endanger the safety of mining areas, leading to roadway collapse, land subsidence and other problems. Determining how to detect goafs accurately and efficiently is an important issue faced in engineering geophysical exploration research. Microtremor survey technology, used in geophysical exploration, has been developed in recent years. It has the advantages of low cost, flexible construction, low topographic impact and high efficiency. In this paper, microtremor survey technology was applied to the detection of a coal mine goaf. In the known goaf area of the Taiyuan Nanling Coal Mine, a linear observation array was arranged to conduct rolling acquisition, observe the microtremor signal records of the natural field and use the extended spatial autocorrelation method to extract the dispersion curve. Through the inversion of the extracted dispersion curve, the apparent shear wave velocity profile of the underground medium clearly showed the location of the goaf. It was roughly consistent with the goaf data obtained from the mine. The detection results reflect the advantages of micromotion exploration. The goaf of Coal Seam #2 and its affected area appear to be due to an obvious low-speed phenomenon. The boundary of the apparent shear wave velocity profile of micromotion detection was basically consistent with the boundary of the goaf, indicating that micromotion exploration technology has good technical advantages and application prospects in the detection of coal mine goafs. The rolling acquisition method of linear arrays can be used to ensure accurate detection, improve exploration efficiency and save on exploration costs.

This paper presents a new scheme of applying CORPS (coherently radiating periodic structures) for reducing the number of phase shifters in linear antenna arrays. This scheme can be seen as a combination of the properties of two techniques: CORPS and butler. The proposed system applies an interleaving of several blocks of 2 × 3 CORPS networks. This interleaving of two stages of 2 × 3 CORPS networks is made in a convenient way to provide the required progressive phase for beam-scanning and the level of amplitude excitations necessary for achieving the radiation characteristics of low SLL. Interesting results are provided based on experimental measurements and full-wave simulations to analyze and evaluate the performance of the feeding network based on CORPS and the reduction capability of the number of phase shifters in the antenna system. The proposed design methodology achieves a reduction capability of 66% in the number of phase shifters used in linear antenna arrays. This reduction in the complexity of the antenna system is reached maintaining a peak SLL of −22 dB with scanning ranges of until ±25°. A good design option is provided to simplify the complexity of the feeding network in antenna array applications.

A complementary source array with enhanced beamwidth is presented based on the substrate-integrated waveguide (SIW) in this communication. The orthogonal complementary source consists of a SIW slot and a vertical monopole, of which the radiation pattern is heart-shaped, pointing to the direction perpendicular to both slot and monopole. To achieve an enhanced beamwidth from the heart-shaped pattern, the complementary sources are cascaded to form an array. In particular, the slots are etched alternately on both sides of the central axis to achieve an in-phase excitation, while the monopoles are uniformly loaded with an alternate antiphase excitation. This arrangement makes the heart-shaped pattern of each complementary source element alternately point to either side of the array axis, so that the synthesized radiation beamwidth is enhanced in the E-plane. Based on the proposed idea, a nine-element line array is designed, fabricated, and tested. Compared with the same-sized referenced SIW slot array with an E-plane half-power beamwidth (HPBW) of only 80°, the proposed complementary source array extends the HPBW to 180°. [ABSTRACT FROM AUTHOR]

A novel two-element MIMO antenna that covers almost the entire terahertz band by its multiband characteristics is proposed in this paper. Initially, an antenna having multiple inverted "L" arms to realize multiple operating bands across the THz range is designed with Rogers RT6010 dielectric. This is then extended into two linear arrays separated by isolating structure to form MIMO antenna with eight bands (1.57, 2.05, 3.46, 4.47, 6.82, 8.3, 8.9, and 9.6 THz) having a miniaturized size of 28 × 40 µm. Thus the combination of MIMO and THz frequency brings high gain, high efficiency, and higher data rate along with maximum reliability. These advantages of the proposed antenna find its applications in the fields of medical, automotive, food processing, etc. The proposed MIMO antenna multiband characteristics are validated with the simulation results and its radiation patterns at certain frequencies are analyzed. [ABSTRACT FROM AUTHOR]

As x-ray acoustic imaging (XAI) moves towards the external beam radiation therapy (EBRT) environment, introducing new practical XAI dosimetry systems with clinical ultrasound scanner becomes a significant contribution, especially using noise reduction methods that can increase the typical low signal-to-noise ratio (SNR) of XA images. In addition, experimental validation of multidomain XAI simulation is of great importance for accurate dose estimation. Therefore, in the present study, a XAI system combining a clinical linear particle accelerator (LINAC) and a linear array transducer connected to a clinical ultrasound scanner was developed. The capability of acquiring XA signal and generating images was investigated with simulations and experiments. PENELOPE and k-wave environments were combined to simulate the XAI system, which was used to generate XA images of different metals and bone in a water tank. A Daubechies's wavelet denoise method was proposed to improve XAI's SNR, where a threefold improvement in SNR of XA image of the bone sample was achieved. The denoised XA experimental images agreed well with simulations in terms of spatial profiles and signal amplitude dose–response slope values, therefore validating the multidomain simulations. [ABSTRACT FROM AUTHOR]

This paper investigates wireless power transmission (WPT) system efficiency of antenna arrays in free space and in fully enclosed boxes with reflecting walls. In this study we investigate the WPT approach for both a uniform transmitting antenna array and a random array. Specifically, we consider 10 transmitting antennas (Tx) placed on two opposite walls of a cubical room and one receiving antenna (Rx) centered in the middle. We calculate the received (Rx) power for different array configurations. Simulation results show that randomness and the presence of reflecting walls provide significant enhancement to the system's power transfer efficiency compared to the maximum efficiency achievable with a similar configuration in free space. Furthermore, the simulated power flow density shows multiple hotspots in space, making the system very dynamic with the advantage of random array over the linear array. This enables power delivery to a moving receiver and meets the demand of harvesting the wireless energy to charge or power up multiple devices at the same time. [ABSTRACT FROM AUTHOR]

In this article, a 16 × 4 linear array of β-Ga2O3-based metal-semiconductor-metal structured photodetector is described for solar-blind sensing operation at a wavelength of 254 nm. The β-Ga2O3 film is grown by using metal-organic chemical vapor deposition (MOCVD) equipment, and the photodetectors are finished in constructing with standard photolithography and ion beam sputtering procedures. The results show that the dark current (Idark), photo-to-dark current ratio (PDCR), photo responsivity (R), specific detectivity (D*), exterl quantum efficiency (EQE), and linear dynamic region (LDR) are 1.94 pA, 2.95 × 107, 139.56 A/W, 2.55 × 1015 Jones, 6.8 × 104 %, and 149.4 dB, at 10 V bias and 2000 μW/cm2 light intensity illumination. In addition, the standard deviation of R for this photodetector array is 10%. Overall, such a 16 × 4 linear array of β-Ga2O3-based photodetector array makes a progress in the field of Ga2O3 photodetectors. [ABSTRACT FROM AUTHOR]

In this study, a compact series-fed center-fed open-stub (SFCFOS) linear array antenna for K-band applications is presented. The antenna is composed of a single-line 10-element linear array. A symmetrical Chebyshev amplitude distribution (CAD) is used to obtain a low sidelobe characteristic against a uniform amplitude distribution (UAD). The amplitude is controlled by varying the width of the microstrip patch elements, and open-ended stubs are arranged next to the last antenna element to use the energy of the radiating signal more effectively. We insert a series-fed stub between two patches and obtain a low mutual coupling for a 4.28-mm center-to-center spacing (0.7λ at 21 GHz). A prototype of the antenna is fabricated and tested. The overall size of the uniform linear array is 7.04 × 1.05 × 0.0563 λg3 and that of the Chebyshev linear array is 9.92 × 1.48 × 0.0793 λ g3. The UAD array yields a |S11| < −10 dB bandwidth of 1.33% (20.912–21.192 GHz) and 1.45% (20.89–21.196 GHz) for the CAD. The uniform array design gives a −23 dB return loss, and the Chebyshev array achieves a −30.68 dB return loss at the center frequency with gains of 15.3 dBi and 17 dBi, respectively. The simulated and measured results are in good agreement.

Simulation involves predicting the responses of a physical system. In this article, we simulate opto-acoustic signals generated in a 3-D volume due to the absorption of an optical pulse. A separable computational model is developed, which splits processing into two steps, permitting an order-of-magnitude improvement in computational efficiency over a nonseparable model. The simulated signals represent acoustic waves, measured by a probe with a linear transducer array, in a rotated and translated coordinate frame. Light is delivered by an optical source that moves with the probe’s frame. Spatiotemporal impulse response for rectangular-element transducer geometry is derived using Green’s function solution to the acoustic wave equation. The approach permits fast and accurate simulation for a probe with an arbitrary trajectory, which is useful for modeling freehand acquisitions. For a 3-D volume of n3 voxels, computation is accelerated by a factor of n. This may potentially have application in opto-acoustic imaging, where clinicians visualize structural and functional features of biological tissue for assessment of cancer and other diseases. [ABSTRACT FROM AUTHOR]

Pulsed laser diodes (PLDs) promise to be an attractive alternative to solid-state laser sources in photoacoustic tomography (PAT) due to their portability, high-pulse repetition frequency (PRF), and cost effectiveness. However, due to their lower energy per pulse, which, in turn, results in lower fluence required per photoacoustic signal generation, PLD-based photoacoustic systems generally have maximum imaging depth that is lower in comparison to solid-state lasers. Averaging of multiple frames is usually employed as a common practice in high PRF PLD systems to improve the signal-to-noise ratio of the PAT images. In this work, we demonstrate that by combining the recently described approach of subpitch translation on the receive-side ultrasound transducer alongside averaging of multiple frames, it is feasible to increase the depth sensitivity in a PLD-based PAT imaging system. Here, experiments on phantom containing diluted India ink targets were performed at two different laser energy level settings, that is, 21 and $27~\mu \text{J}$. Results obtained showed that the imaging depth improves by ~38.5% from 9.1 to 12.6 mm for 21- $\mu \text{J}$ energy level setting and by ~33.3% from 10.8 to 14.4 mm for 27- $\mu \text{J}$ energy level setting by using $\lambda $ /4-pitch translation and average of 128 frames in comparison to $\lambda $ -pitch data acquired with the average of 128 frames. However, the achievable frame rate is reduced by a factor of 2 and 4 for $\lambda $ /2 and $\lambda $ /4 subpitch translation, respectively. [ABSTRACT FROM AUTHOR]

This paper comprehensively investigates the buckling load and the stability of a planar linear array deployable structure composed of scissor-like element (SLE) under compression. At present, the researches on deployable structure are mainly focused on configuration design and dynamics characteristics of the mechanisms, but less research on structural instability. In fact, when the external load exceeds the structural critical load value, the deployable structure will be permanently deformed or even collapse directly and no longer have any bearing capacity. To address this issue, a new stability model is derived using linear elastic analysis method and substructure method to evaluate the buckling characteristics of the deployable structure with n SLEs when it is carried out in space, which can accurately obtain the structural instability load and can be used quantitatively to optimize the structure for making it have the most stable configuration. In addition, the effects of the number of elements, the length, material properties and flexibility of the bar, and the deployment degree on the buckling of the scissor deployable structure are investigated, and the results of the theoretical analysis are compared with simulation and analytical results, respectively, confirming that the proposed stability model not only is able to effectively predict the structural instability load but also determine which part of the deployable structure is unstable. It can be concluded that the stability of the deployable structure gradually decreases with the increase of the number of elements or the bar flexibility. In the calculation process, the critical load of each sub-element should be considered, and the minimum value of the critical loads of all subunits can be regarded as the instability load of the whole structure. [ABSTRACT FROM AUTHOR]

Featured Application: This single-side access 3-D synthetic aperture scanning method can be readily applied with existing 1-D transducer arrays to more reliably monitor response of lesions over the course of therapy. We proposed a novel solution for volumetric ultrasound imaging using single-side access 3-D synthetic aperture scanning of a clinical linear array. This solution is based on an advanced scanning geometry and a software-based ultrasound platform. The rotate-translate scanning scheme increases the elevation angular aperture by pivoting the array (−45° to 45°) around its array axis (axis along the row of its elements) and then scans the imaged object for each pivoted angle by translating the array perpendicularly to the rotation axis. A theoretical basis is presented so that the angular and translational scan sampling periods can be best adjusted for any linear transducer array. We experimentally implemented scanning with a 5-MHz array. In vitro characterization was performed with phantoms designed to test resolution and contrast. Spatial resolution assessed based on the full-width half-maximum of images from isolated microspheres was increased by a factor of 3 along the translational direction from a simple translation scan of the array. Moreover, the resolution was uniform over a cross-sectional area of 4.5 cm2. Angular sampling periods were optimized and tapered to decrease the scan duration while maintaining image contrast (contrast at the center of a 5-mm cyst on the order of −26 dB for 4° angular period and a scan duration of 10 s for a 9-cm3 volume). We demonstrated that superior 3-D ultrasound imaging can be obtained with a clinical array using our scanning strategy. This technique offers a promising and flexible alternative to development of costly matrix arrays toward the development of sensitive volumetric ultrasonography. [ABSTRACT FROM AUTHOR]

Research on photoacoustic imaging (PAI) using a handheld integrated photoacoustic probe has been a recent focus of clinical translation of this imaging technique. One of the remaining challenges is the occurrence of out-of-plane artifacts (OPAs) in such a probe. Previously, we proposed a method to identify and remove OPAs by axially displacing the transducer array. Here we show that besides the benefit of removing OPAs from the imaging plane, the proposed method can provide a three-dimensional (3D) view of the OPAs. In this work, we present a 3D reconstruction method using axial transducer array displacement. By axially displacing the transducer array, out-of-plane absorbers can be three-dimensionally visualized at an elevation distance of up to the acquired imaging depth. Additionally, OPAs in the in-plane image are significantly reduced. We experimentally demonstrate the method with phantom and in vivo experiments using an integrated PAI probe. We also compare the method with elevational transducer array displacement and take into account the sensitivity of the transducer array in the 3D reconstruction.

Introduction: Oral human papillomavirus (HPV) attributable oropharyngeal cancers are on the rise in many countries. Oral HPV infections among healthy individuals are commonly detected using oral gargle samples. However, the optimal method for HPV genotyping oral gargle specimens in research studies has not been previously evaluated. Materials and methods: Oral gargle samples from 1455 HPV Infection in Men (HIM) study participants were HPV genotyped using two different methods: Linear Array and the SPF10 PCR-DEIA-LiPA25. The sensitivity of the two tests for detecting individual HPV types and grouped HPV types, high-risk HPV, low-risk HPV, grouped 4-HPV-vaccine types, and grouped 9-HPV-vaccine-types, and the degree of concordance between the two tests was assessed. We also examined whether socio-demographic-behavioral factors were associated with concordance between the two assays. Results: The sensitivity of SPF10 PCR-DEIA-LiPA25 was higher than Linear Array, with the exception of HPV 70, for the detection of oral HPV. The prevalence ratio of SPF10 PCR-DEIA-LiPA25 to Linear Array varied between 1.0 and 9.0 for individual HPV genotypes, excluding HPV 70, and between 3.8 and 4.4 for grouped 4-valent and 9-valent HPV vaccine types, respectively. There was no association between socio-demographic-behavioral factors and discordance in results between the two tests for oral HPV 16 detection. Discussion: SPF10 PCR-DEIA-LiPA25 was more sensitive than Linear Array for detecting HPV in oral gargle samples. Given the growing importance of detecting oral HPV infection for research studies of oral HPV natural history and vaccine effectiveness evaluation, we recommend using methods with higher sensitivity such as SPF10 PCR-DEIA-LiPA25 for detecting HPV in oral gargle samples.