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14 pages, 609 KiB

Open AccessArticle

Synthesising a Fixed-Length Equispaced Linear Array to Produce Dolph–Chebyshev Patterns with Deep Nulls, a Desired Side Lobe Level and Different Beamwidths

by Ibai Otero-Gómez, María Elena López-Martín, Juan Antonio Rodríguez-González and Francisco José Ares-Pena

Sensors 2025, 25(6), 1685; https://doi.org/10.3390/s25061685 - 8 Mar 2025

Viewed by 725

Abstract

A method for the synthesis of equally spaced antenna arrays based on the extension of the Orchard–Elliott–Stern technique to radiation patterns with three roots on the negative real axis of the Shelkunoff unit circle is presented. One of these roots is placed on [...] Read more.

A method for the synthesis of equally spaced antenna arrays based on the extension of the Orchard–Elliott–Stern technique to radiation patterns with three roots on the negative real axis of the Shelkunoff unit circle is presented. One of these roots is placed on the unit circle and the other two are off the unit circle with coordinates r and

1 / r

. For a desired side lobe level (SLL), the synthesis of patterns with these roots allows for a multiplicity of solutions with different amplitude ratios, obtained by varying the value of r, each of which presents radiation patterns with different beamwidths and directivity, but with two fewer side lobes than the patterns obtained without these restrictions in the roots. The technique has been thoroughly applied to Dolph–Chebyshev patterns of 10, 18 and 40 elements, with a

λ / 2

spacing and an SLL that guarantees maximum directivity in both cases. This approach ensures the study of examples of all sizes, from small to large. The findings derived from this technique would be applicable in the domain of wireless communications, where the necessity arises for radiation patterns that exhibit low SLL and adaptive beamwidth. Full article

(This article belongs to the Section Sensor Networks)

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16 pages, 5579 KiB

Open AccessArticle

On Difference Pattern Synthesis for Spherical Sensor Arrays

by Zhijiang Huang, Maolin Chen, Xianglu Li, Shunqin Xie, Guoning Ma and Jie Tian

Sensors 2024, 24(7), 2361; https://doi.org/10.3390/s24072361 - 8 Apr 2024

Viewed by 1491

Abstract

An innovative method for synthesizing optimum difference patterns of the spherical sensor array is introduced, along with a sidelobe tapering technique. Firstly, we suggest employing the spherical harmonics of degree ±1 to synthesize the spherical array difference pattern; secondly, we study the mapping [...] Read more.

An innovative method for synthesizing optimum difference patterns of the spherical sensor array is introduced, along with a sidelobe tapering technique. Firstly, we suggest employing the spherical harmonics of degree ±1 to synthesize the spherical array difference pattern; secondly, we study the mapping relationship between the difference pattern of the spherical sensor array and the difference pattern of the uniformly spaced linear array (ULA) with odd-numbered elements; finally, we enhance the Zolotarev difference pattern, which is a counterpart to the Dolph–Chebyshev sum pattern that traditionally allows synthesis only for ULA with even-numbered elements. Our modification extends its applicability to synthesize difference patterns for ULA with odd-numbered elements. Leveraging the optimal difference pattern, a generalized Bayliss difference pattern synthesis method designed for the ULA with odd-numbered elements is further proposed. To illustrate the effectiveness of our approach, we present several design examples through experimental simulation. Full article

(This article belongs to the Section Electronic Sensors)

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17 pages, 6513 KiB

Open AccessArticle

Multi-Objective NSGA-II Optimization for Broadband Beamforming with Spherical Harmonic Domain Assistance

by Zhenghong Liu, Haocheng Zhou, Xiyu Song, Mei Wang and Liuqing Weng

Sensors 2023, 23(20), 8403; https://doi.org/10.3390/s23208403 - 12 Oct 2023

Cited by 1 | Viewed by 1819

Abstract

Sidelobe suppression is a major challenge in wideband beamforming for acoustic research, especially in high noise and reverberation environments. In this paper, we propose a multi-objective NSGA-II wideband beamforming method based on a spherical harmonic domain for spherical microphone arrays topology. The method [...] Read more.

Sidelobe suppression is a major challenge in wideband beamforming for acoustic research, especially in high noise and reverberation environments. In this paper, we propose a multi-objective NSGA-II wideband beamforming method based on a spherical harmonic domain for spherical microphone arrays topology. The method takes white noise gain, directional index and maximum sidelobe level as the optimization objectives of broadband beamforming, adopts the NSGA-II optimization strategy with constraints to estimate the Pareto optimal solution, and provides three-dimensional broadband beamforming capability. Our method provides superior sidelobe suppression across different spherical harmonic orders compared to commonly used multi-constrained single-objective optimal beamforming methods. We also validate the effectiveness of our proposed method in a conference room setting. The proposed method achieves a white noise gain of 8.28 dB and a maximum sidelobe level of −23.42 dB at low frequency, while at high frequency it yields comparable directivity index results to both DolphChebyshev and SOCP methods, but outperforms them in terms of white noise gain and maximum sidelobe level, measuring 16.14 dB and −25.18 dB, respectively. Full article

(This article belongs to the Section Physical Sensors)

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19 pages, 8876 KiB

Open AccessArticle

Compact Wearable Antenna with Metasurface for Millimeter-Wave Radar Applications

by María Elena de Cos Gómez, Humberto Fernández Álvarez, Alicia Flórez Berdasco and Fernando Las-Heras Andrés

Materials 2023, 16(7), 2553; https://doi.org/10.3390/ma16072553 - 23 Mar 2023

Cited by 3 | Viewed by 2137

Abstract

Three metasurfaces (MTS) are designed to be combined with a series end-fed 1 × 10 array antenna with a modified Dolph-Chebyshev distribution for imaging applications in the millimeter frequency range, 24.05–24.25 GHz. A reduction in secondary lobes and an increase in FTBR can [...] Read more.

Three metasurfaces (MTS) are designed to be combined with a series end-fed 1 × 10 array antenna with a modified Dolph-Chebyshev distribution for imaging applications in the millimeter frequency range, 24.05–24.25 GHz. A reduction in secondary lobes and an increase in FTBR can be achieved while preserving gain, radiation efficiency, SLL and size using an MTS–array combination. Moreover, as a result of each single-layer MTS–array combination, operation bandwidth is widened, with gain and radiation efficiency enhancement. The overall devices’ size is 86.8 × 12 × 0.762 mm³. The envisioned application is collision avoidance in aid to visually impaired people at a medium-long distance. Full article

(This article belongs to the Special Issue Metamaterial and Metasurface Design for Microwave Applications)

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9 pages, 13974 KiB

Open AccessArticle

5G UFMC Scheme Performance with Different Numerologies

by Lambros Sakkas, Eleftherios Stergiou, Georgios Tsoumanis and Constantinos T. Angelis

Electronics 2021, 10(16), 1915; https://doi.org/10.3390/electronics10161915 - 10 Aug 2021

Cited by 12 | Viewed by 5037

Abstract

5G is the latest mobile communications standard that is spreading fast across the world. Recently defined requirements for 5G systems have led to higher applications’ requirements regarding data rates, lower requirements for latency, and higher efficiency regarding the spectrum usage. Universal Filtered Multi-Carrier [...] Read more.

5G is the latest mobile communications standard that is spreading fast across the world. Recently defined requirements for 5G systems have led to higher applications’ requirements regarding data rates, lower requirements for latency, and higher efficiency regarding the spectrum usage. Universal Filtered Multi-Carrier (UFMC) is one new candidate modulation scheme for emergent Fifth Generation (5G) communication systems. This paper focuses on Universal Filtered Multi-Carrier (UFMC) design aspects in terms of Bit Error Rate (BER) performance in relation to the filter length used in subband filtering. Simulation results show that BER and CCDF performance varies for different filter lengths and modulation schemes. The main achievement of this work is that the results show that different Dolph–Chebyshev FIR filter lengths do not affect the BER performance both for the 64 and 256 QAM. Full article

(This article belongs to the Special Issue Enabling-5G)

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16 pages, 6272 KiB

Open AccessArticle

An Efficient Fast and Convergence-Controlled Algorithm for Sidelobes Simultaneous Reduction (SSR) and Spatial Filtering

by Yasser Albagory

Electronics 2021, 10(9), 1071; https://doi.org/10.3390/electronics10091071 - 30 Apr 2021

Cited by 3 | Viewed by 2057

Abstract

In this paper, an efficient sidelobe levels (SLL) reduction and spatial filtering algorithm is proposed for linear one-dimensional arrays. In this algorithm, the sidelobes are beamspace processed simultaneously based on its orientation symmetry to achieve very deep SLL at much lower processing time [...] Read more.

In this paper, an efficient sidelobe levels (SLL) reduction and spatial filtering algorithm is proposed for linear one-dimensional arrays. In this algorithm, the sidelobes are beamspace processed simultaneously based on its orientation symmetry to achieve very deep SLL at much lower processing time compared with recent techniques and is denoted by the sidelobes simultaneous reduction (SSR) algorithm. The beamwidth increase due to SLL reduction is found to be the same as that resulting from the Dolph-Chebyshev window but at considerably lower average SLL at the same interelement spacing distance. The convergence of the proposed SSR algorithm can be controlled to guarantee the achievement of the required SLL with almost steady state behavior. On the other hand, the proposed SSR algorithm has been examined for spatial selective sidelobe filtering and has shown the capability to effectively reduce any angular range of the radiation pattern effectively. In addition, the controlled convergence capability of the proposed SSR algorithm allows it to work at any interelement spacing distance, which ranges from tenths to a few wavelength distances, and still provide very low SLL. Full article

(This article belongs to the Section Microwave and Wireless Communications)

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16 pages, 25393 KiB

Open AccessArticle

A Modified Dolph-Chebyshev Type II Function Matched Filter for Retinal Vessels Segmentation

by Dhimas Arief Dharmawan, Boon Poh Ng and Susanto Rahardja

Symmetry 2018, 10(7), 257; https://doi.org/10.3390/sym10070257 - 3 Jul 2018

Cited by 6 | Viewed by 3576

Abstract

In this paper, we present a new unsupervised algorithm for retinal vessels segmentation. The algorithm utilizes a directionally sensitive matched filter bank using a modified Dolph-Chebyshev type II basis function and a new method to combine the matched filter bank’s responses. Fundus images [...] Read more.

In this paper, we present a new unsupervised algorithm for retinal vessels segmentation. The algorithm utilizes a directionally sensitive matched filter bank using a modified Dolph-Chebyshev type II basis function and a new method to combine the matched filter bank’s responses. Fundus images from the DRIVE and STARE databases, as well as high-resolution fundus images from the HRF database, are utilized to validate the proposed algorithm. The results that we achieve on the three databases (DRIVE: Sensitivity = 0.748, F1-score = 0.786, G-score = 0.856, Matthews Correlation Coefficient = 0.758; STARE: Sensitivity = 0.793, F1-score = 0.780, G-score = 0.877, Matthews Correlation Coefficient = 0.756; HRF: Sensitivity = 0.804, F1-score = 0.764, G-score = 0.883, Matthews Correlation Coefficient = 0.741) are higher than many other competing methods. Full article

(This article belongs to the Special Issue Symmetry in Computing Theory and Application)

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12 pages, 864 KiB

Open AccessArticle

Design and Performance Analysis of Capacitive Micromachined Ultrasonic Transducer Linear Array

by Hongliang Wang, Xiangjun Wang, Changde He and Chenyang Xue

Micromachines 2014, 5(3), 420-431; https://doi.org/10.3390/mi5030420 - 3 Jul 2014

Cited by 38 | Viewed by 7781

Abstract

An ultrasonic transducer is a key component to achieve ultrasonic imaging. This paper designs a new type of Microelectromechanical Systems (MEMS) based capacitive ultrasonic transducer and a linear array based on the transducer. Through directivity analysis, it can be found that its directivity [...] Read more.

An ultrasonic transducer is a key component to achieve ultrasonic imaging. This paper designs a new type of Microelectromechanical Systems (MEMS) based capacitive ultrasonic transducer and a linear array based on the transducer. Through directivity analysis, it can be found that its directivity is weak due to the small size of the designed transducer, but the directivity of the designed linear array is very strong. In order to further suppress the sidelobe interference and improve the resolution of the imaging system and imaging quality, the Dolph-Chebyshev weighting method and the Taylor weighting method are used to process −40dB sidelobe suppression, and satisfactory results are obtained, which can meet actual requirements. Full article

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