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Grating Lobe/Sidelobe Suppression Method for Near-Field Distributed MIMO Imaging array

IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION 2025年第3期73卷 1674-1687页

作者： He, Jiacheng Wang, Jun Yang, Bin Zhao, Ke Sun, Jinping Beihang Univ Sch Elect & Informat Engn Beijing 100191 Peoples R China Beihang Univ Hangzhou Innovat Inst Hangzhou 310000 Peoples R China

Distributed multiple-input-multiple-output(MIMO)arrays obtain a larger virtual aperture by combining subarrays at different locations. However, subarray spacing leads to sparse spatial sampling, introducing grating lobes in the imaging results. In this article, we propose a grating lobe suppression method utilizing array pattern migration and multiapodization (MA) for large-aperture distributed MIMO imaging arrays under near-field conditions. The MA processing includes applying multiple sets of compensation weights to achieve pattern migration of the imaging result and selecting the minimum value as the output. For further image quality improvement, we derive sum and difference images of the imaging results from sum and difference patterns of the array factor, and then propose a novel sidelobe suppression method utilizing weighted sum and difference (WSD) image cancellation. On this basis, we combine the two proposed methods with the backprojection (BP) algorithm through adaptive weighting techniques to eliminate the spatially variant characteristics of the array pattern in the near-field range, introducing a weighted BP (WBP) algorithm for near-field imaging. The effectiveness of the proposed methods has been verified through multiple simulations, measurements, and a publicly available dataset.

关键词： Gratings Imaging Radar imaging Apertures Vectors Radar Antennas and propagation Signal processing algorithms Phased arrays MIMO radar array pattern distributed multiple-input-multiple-output (MIMO) array grating lobe/sidelobe suppression multiapodization (MA) sum/difference images

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Taylor-Series-Based Derivation of the Resolution of Null Subtraction Imaging for a Uniform Linear array

IEEE OPEN JOURNAL OF ULTRASONICS, FERROELECTRICS, AND FREQUE...

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IEEE OPEN JOURNAL OF ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2025年 5卷 19-22页

作者： Han, Chaoran Nasholm, Sven Peter Austeng, Andreas Arnestad, Havard Kjellmo Univ Oslo Dept Informat N-0316 Oslo Norway

Null subtraction imaging (NSI) is a non-linear beamformer that aims to improve the spatial resolution of ultrasound images. NSI incoherently combines three delay-and-sum (DAS) outputs from the same RF data using three related apodizations on receive. NSI has been advocated to have many advantages in different domains such as B-mode imaging, plane wave imaging, power Doppler imaging, and for large-pitch arrays. However, despite its increasing popularity, an explicit relationship between NSI resolution (interpreted as the mainlobe width) and various parameters (such as the DC offset value c, array aperture, and wavelength) is not known, making system design and intuitive reasoning about the method difficult. Therefore, in the current work, we derive the theoretical NSI array pattern and give an approximate expression for the -6dB mainlobe width. Our derivation is based on a Taylor series-expansion of the analytical NSI array pattern, which is valid over the mainlobe region for the range of c values typically seen in the literature. The results show that the NSI mainlobe width is proportional to c lambda/D , which is the DC offset value multiplied by the wavelength and divided by the aperture size, and therefore has a similar wavelengh and aperture dependency as the classical DAS mainlobe. The work is validated numerically, also showing that the NSI mainlobe width approaches the DAS mainlobe width as c approaches infinity.

关键词： Imaging array signal processing Apertures Ultrasonic imaging Fourier transforms Finite element analysis Upper bound Spatial resolution Radio frequency Gratings array pattern beamforming FWHM mainlobe width medical ultrasound null subtraction imaging (NSI)

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Optimal Design of Cymbal array patterns to Achieve Broadband Characteristics Using an Equivalent Circuit

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IEEE SENSORS JOURNAL 2023年第19期23卷 22285-22294页

作者： Shim, Hayeong Mudiyala, Jahnavi Roh, Yongrae Kyungpook Natl Univ Sch Mech Engn Daegu 41566 South Korea

In this study, a new general and systematic design method to maximize the bandwidth of a cymbal array was developed by using an equivalent circuit. Initially, through the analysis of the acoustic interaction between the cymbal transducers in a 3 x 3 array, the overall design scheme was developed using the center frequency (CF) and transmitting voltage response (TVR) level of the transducers as variables. The validity of the design was verified through a comparison with the results obtained using the finite-element method (FEM). Then, the optimal design method for a general N x N cymbal array was derived to achieve the widest bandwidth. The efficacy of the method was demonstrated by designing 4 x 4 and 5 x 5 arrays as sample cases. The new method can incorporate multiple design variables and reflect the effects of nonlinear interaction between the variables to design the optimal array pattern of cymbal transducers.

关键词： array pattern cymbal transducer equivalent circuit optimal design wideband

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DOA/MoM-based ABF algorithm for SINR enhancement

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IET COMMUNICATIONS 2019年第11期13卷 1565-1572页

作者： Dawood, Heba S. Hussein, Amr Hussein Gemeay, Entesar Attia, Mahmoud Ahmed Tanta Univ Fac Engn Elect & Elect Commun Dept Tanta Egypt

In this study, a new non-iterative adaptive beamforming (ABF) algorithm for the signal-to-interference and noise ratio (SINR) enhancement is proposed. It is based on a combination between the direction of arrival (DOA) estimation and the method of moments (MoM). The proposed algorithm is denoted as DM/ABF which stands for DOA and MoM-based ABF. The DOA is used to provide accurate estimates for the directions of the desired and interfering signals. On the basis of the estimated DOAs, a dedicated shaped pattern version of the ordinary pattern is created and applied as the desired input to the MoM algorithm. The MoM is used for shaped pattern synthesis to estimate the weights vector required to provide deep nulls toward the interfering signals and directs the main beam toward the desired signal. In this case, the weights vector does not update iteratively at each received signal sample as in case of least mean square (LMS) and recursive least squares (RLSs) algorithms, but it is updated only when the estimated DOAs of the desired and interfering signals are changed. Furthermore, a large number of close nulls can be produced without the need for additional antenna elements compared with other algorithms.

关键词： direction-of-arrival estimation array signal processing method of moments least mean squares methods adaptive antenna arrays antenna radiation patterns interference (signal) SINR enhancement smart antenna systems adaptive beamforming array pattern desired direction interfering signals noniterative ABF algorithm arrival estimation desired signals dedicated shaped pattern version ordinary pattern desired input MoM algorithm shaped pattern synthesis weights vector desired signal received signal sample direction-of-arrival MoM-based ABF algorithm signal-to-interference-and-noise ratio enhancement method-of-moments least mean square algorithm recursive least squares algorithm LMS algorithm RLS algorithm

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Compact, two-element array with high broadside directivity

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IET MICROWAVES ANTENNAS & PROPAGATION 2013年第8期7卷 663-671页

作者： Tang, Ming-Chun Ziolkowski, Richard W. Univ Elect Sci & Technol China Inst Appl Phys Chengdu 610054 Peoples R China Chongqing Univ Coll Commun Engn Chongqing 400044 Peoples R China Univ Arizona Dept Elect & Comp Engn Tucson AZ 85721 USA

A combination of two high directivity, electrically small, slot-modified conducting disc-augmented Egyptian axe dipole (EAD) antennas is investigated to achieve interesting broadside radiation properties, including a high broadside directivity and front-to-back ratio. Their array arrangement is guided by a simple two-element dipole model. The parasitic conducting disc associated with each EAD antenna is modified only slightly from their original single-element dimensions to preserve nearly complete matching to their sources, to accommodate the coupling between the two elements and to maximise the array pattern characteristics. Parameter studies lead to a final design, whose simulation results demonstrate that the two-element array has outstanding performance characteristics, including a 9.98 dB broadside directivity, an 88.19% radiation efficiency, a 20.03 dB front-to-back-ratio, a -22.42 dB mutual coupling level, more than a 30 dB level of polarisation purity, and good impedance matching to their respective 50 Omega sources, despite each antenna being electrically small, that is, ka < 1, and the distance between the centre of each element being only slightly larger than a half wavelength.

关键词： antenna arrays dipole antennas directive antennas radiation detection gain 9.98 dB gain 30 dB gain 22.42 dB gain 20.03 dB array pattern single element dimensions array arrangement front-to-back ratio broadside radiation properties EAD antennas Egyptian axe dipole antennas broadside directivity two-element array

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Interference suppression of linear antenna arrays by amplitude-only control using a bacterial foraging algorithm

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PROGRESS IN ELECTROMAGNETICS RESEARCH-PIER 2008年 79卷 475-497页

作者： Guney, K. Basbug, S. Erciyes Univ Fac Engn Dept Elect & Elect Engn TR-38039 Kayseri Turkey Nevsehir Univ Vocat Coll Dept Ind Elect Nevsehir Turkey

This paper presents a bacterial foraging algorithm (BFA) for null steering of linear antenna arrays by controlling only the element amplitudes. The BFA is a new evolutionary computing technique based on the foraging behavior of Escherichia (E.) coli bacteria in human intestine. To show the accuracy and. exibility of the proposed BFA, several examples of Chebyshev array pattern with the imposed single, multiple and broad nulls are given. It is found that the nulling method based on BFA is capable of steering the array nulls precisely to the undesired interference directions.

关键词： .Chebyshev nulling broad nulls pattern synthesis array pattern BACTERIAL FORAGING element amplitudes

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Effects of SNR-Dependent Beam Alignment Errors on Millimeter-Wave Cellular Networks

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IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 2022年第5期71卷 5216-5230页

作者： Zia, Muhammad Saad Blough, Douglas M. Weitnauer, Mary Ann Georgia Inst Technol Sch Elect & Comp Engn Atlanta GA 30332 USA

At millimeter-wave (mm-wave) frequencies, narrow beamwidth and inaccurate channel estimation result in beam alignment errors, which degrade the achievable signal-to-noise ratio (SNR) and rate. The extent of beam misalignment depends on the various link parameters, however, prior works ignored such a dependence and considered oversimplified array patterns. This paper formulates beam alignment errors for the uniform linear array at the base station as a function of the link parameters by using the Cramer Rao lower bound of angle-of-arrival estimates and proposes a tractable array pattern approximation to better reflect the effects of such alignment errors. Utilizing stochastic geometry and the statistics of the Student's t-distribution, a novel and robust analytical technique is developed to obtain the downlink SNR and rate coverage probabilities due to beam misalignment, assuming a single antenna at the user. We show that beam alignment errors significantly affect the achievable SNR and rate for non line-of-sight (NLOS)/distant users whereas the effect is negligible for LOS/nearby users. It is also illustrated that the effects of alignment errors cannot be mitigated only by increasing the number of antennas. We also show that our proposed array pattern approximation better captures the effects of beam alignment errors as compared to the widely used flat-top pattern.

关键词： Signal to noise ratio Antenna arrays Training array signal processing Channel estimation Standards Downlink array pattern beam alignment error Cramer Rao lower bound element pattern Student's t-distribution

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Improved alternating projection algorithm for pattern synthesis with dual polarised conformal arrays

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IET MICROWAVES ANTENNAS & PROPAGATION 2020年第9期14卷 891-896页

作者： Liu, Chao Li, Chuan Yang, Bo Hefei Univ Technol Dept Elect & Commun Engn Hefei 230601 Peoples R China

Inthis study, an improved alternating projection algorithm is presented for the pattern synthesis of a dual-polarised conformal array. An extra desired pattern is introduced to find an appropriate solution in the process of projecting the desired solution set to the feasible solution set. Virtual interferences are introduced to modify the solution iteratively based on the deviation between the obtained and desired pattern. Finally, the authors' algorithm is applied to dual-polarised conformal arrays and can achieve a suitable solution set between the predefined upper and lower bounds, which can synthesise both orthogonal polarisation components of the array pattern more effectively. Simulation examples are presented to verify the validity of the proposed algorithm.

关键词： iterative methods conformal antennas electromagnetic wave polarisation improved alternating projection algorithm pattern synthesis dual polarised conformal arrays orthogonal polarisation components array pattern

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Null steering method by controlling two elements

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IET MICROWAVES ANTENNAS & PROPAGATION 2014年第15期8卷 1348-1355页

作者： Mohammed, Jafar Ramadhan Sayidmarie, Khalil Hassan Univ Mosul Dept Commun Engn Coll Elect Engn Mosul 41001 Iraq

Null steering in adaptive arrays is usually achieved by controlling the complex weights of all or most of the array elements. This study explores an alternative approach, where only the two side elements of the array are used for null steering. By suitably adjusting the amplitude and phase excitations of these elements, it is possible to modify the overall array pattern to place a wide angular null in the direction of undesired interfering signals. Unlike the adaptive arrays, the proposed method is much simpler in practical implementation.

关键词： beam steering adaptive antenna arrays antenna radiation patterns array signal processing interference suppression null steering method adaptive array complex weight control array side element phase excitation amplitude excitation array pattern angular null undesired interfering signal

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Improve the performance of a linear array by changing the spaces among array elements in terms of genetic algorithm

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IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION 2005年第7期53卷 2226-2230页

作者： Tian, YB Qian, J Nanjing Univ Dept Elect Sci & Engn Nanjing 210093 Peoples R China

The pattern of linear array is optimized via adjusting the current allocations and positions of elements simultaneously in terms of improved genetic algorithm (GA). Optimized results show that minute modification of the element positions can improve the array pattern, especially for the fewer elements case. It is found that the improvements are attributed to additional side lobes, which involved some radiation energy and resulted in reduction of relative side lobe level (RSLL). In the optimal process, some skills, such as the soft constraints linked to the fitness function, the adaptive searching area, the injection of simulated annealing and immune operator etc., are used to make the algorithm more effective.

关键词： array pattern genetic algorithm (GA) soft constraints synthesis

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