Modeling of mutual coupling of arbitrary order in coupled circuits and array antennas

This article presents a fundamental strategy for accurately modeling the mutual coupling of arbitrary order in any large‐scale electromagnetic structures and high‐density integrated chips such as antenna array elements and coupled circuit elements. The proposed method starts from the modeling of the first‐order mutual coupling, and it consists of two main steps. First of all, an equivalent circuit model describing low‐order mutual coupling (adjacent coupling) is characterized and established, of which each parametric value is accurately extracted by making use of a numerical calibration technique. Then, the circuit model for high‐order mutual coupling (crossover or crosstalk coupling) is generated from the lower order models, and it can further be used for the modeling of mutual coupling of any higher order. The accuracy and efficiency of the proposed method are demonstrated by three different kinds of structure including a linear phased array antenna, a finite periodic electromagnetic structure, and a planar low‐pass filter. This novel approach represents an easy, fast, and effective characterization of arbitrary‐order mutual coupling. It can find applications in the modeling of mutual coupling between any circuit elements and building blocks such as antennas, resonators, and even small discontinuities, and it promises to be helpful for the analysis and iterative design of microwave circuits and antenna arrays. © 2010 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2011.     

Antipodal tapered slot antenna array using broadband decoupling structure for mutual coupling reduction

In this article, an effective method to reduce the mutual coupling between the antipodal tapered slot antenna (ATSA) array is proposed. This method is mainly implemented by loading a set of decoupling structures (DS) perpendicular to the dielectric substrate between two antenna elements. The proposed DS can provide transmission forbidden band which can effectively prevent leaked electromagnetic waves. DS can operate in most frequency bands within 4 to 17.5 GHz. It can enhance about 23 dB isolation between the ATSA array without affecting bandwidth and radiation characteristics. The proposed ATSA arrays are fabricated and tested. The measured results can verify its excellent properties. The proposed broadband decoupling method is a suitable candidate for restrain mutual coupling of ultra‐wideband planar end‐fire antennas. This design sheds new light on broadband decoupling.     

Mutual coupling reduction in planar Yagi antenna array using bidirectional absorbing metasurface

An effective method for reducing the mutual coupling between the antenna arrays using a bidirectional absorbing metasurface is proposed in this article. This is achieved by embedding the bidirectional absorbing metasurface between the two planar Yagi antennas. The metasurface is mainly composed of 3 × 6 unit cells. Each unit cell includes three‐layer metal rings and two‐layer dielectric slabs. Since the front and back of the metasurface are completely consistent, a bidirectional absorptivity can reach to 86% or more. Using the proposed metasurface, the mutual coupling at the resonance point can be reduced to about 38 dB. And it has little effect on other performances of the Yagi antennas. Moreover, the proposed metasurface can improve the radiation performance of the antenna array, and make it have a smaller back lobe and a larger front‐to‐back ratio.     

基于均匀圆阵的互耦误差校正算法研究

阵元之间的互耦效应严重影响了DOA的估计性能。基于均匀圆阵,提出了一种互耦条件下的波达方向估计和互耦误差自校正算法。利用带状循环矩阵的特性对均匀圆阵的互耦误差建立数学模型,再利用MUSIC算法和迭代法对互耦误差矩阵和波达方向同时进行估计,自校正方法无需任何辅助阵元即可实现两类参数的估计。仿真实验表明,算法很好地解决了均匀圆阵的互耦问题,能够比较准确地估计出波达方向角和互耦误差值。     

Block rank sparsity-aware DOA estimation with large-scale arrays in the presence of unknown mutual coupling

With the development of massive multiple-input mutiple-output (MIMO) technique, high-resolution direction-of-arrival (DOA) estimation has attracted great attention. A novel sparse signal reconstruction method based on the inherent block rank sparsity of the sub-matrix is proposed for high resolution DOA estimation with large-scale arrays under the condition of unknown mutual coupling. In the proposed method, by taking advantage of the banded symmetric Toeplitz structure of the mutual coupling matrix (MCM), a novel block representation model is firstly formulated by parameterizing the steering vector. Then, exploiting the inherent block sparsity characteristics of the sub-matrix, a reweighted nuclear norm minimization algorithm is proposed to reconstruct the sparse matrix, in which the weighted matrix is designed by using the spectrum of MUSIC-Like algorithm. Finally, the DOAs are achieved by searching the non-zeros blocks of the recovered matrix. The proposed method not only makes full use of the block rank sparsity characteristics of the sub-matrix and weighted matrix for enhancing the sparse solution, but also avoids the array aperture loss. Thus, the proposed method has superior estimation performance than the state-of-the-art algorithms under the condition of unknown mutual coupling. Especially, in the case of large-scale antennas, the advantage of the proposed method is more obvious. Some computer simulation results are performed to verify the advantage of our proposed method.     

Robust DOA estimation and array calibration in the presence of mutual coupling for uniform linear array

The presence of unknown mutual coupling between array elements is knownto significantly degrade the performance of most high-resolution direction of arrival (DOA)estimation algorithms. In this paper, a robust subspace-based DOA estimation and arrayauto-calibration algorithm is proposed for uniformly linear array (ULA), when the arraymutual coupling is present. Based on a banded symmetric Toeplitz matrix model for themutual coupling of ULA, the algorithm provides an accurate and high-resolution DOAestimate without any knowledge of the array mutual couplings. Moreover, a favorableestimate of mutual coupling matrix can also be achieved simultaneously for arrayauto-calibration. The algorithm is realized just via one-dimensional search or polynomialrooting, with no multidimensional nonlinear search or convergence burden involved. Theproblem of parameter ambiguity, statistically consistence and efficiency of the newestimator are also analyzed. Monte-Carlo simulation results are also provided todemonstrate the     

互耦效应下多组相干源的波达方位估计算法

对于实际环境中存在的多径现象和阵元间的互耦效应,提出一种互耦效应下针对相干源的波达方向估计算法。首先,通过波达方向矩阵法利用二阶矩求出互耦效应下的广义导向矢量;然后对广义导向矢量进行 子空间平滑,通过矩阵变换得到一个线性约束下的规划问题,实现相干源方位和互耦系数的级联估计。该算法只需利用二阶矩求得广义导向矢量,相比常规的四阶累积量方法,减少了计算量;本文算法在解互耦和解相干过程中都没有损失阵列孔径,极大提高了阵元利用效率。计算机仿真结果验证了该算法的有效性。     

Localization of mixed far-field and near-field sources under unknown mutual coupling

In this paper, a novel localization algorithm for mixed far-field and near-field sources is proposed in the presence of unknown mutual coupling. Based on the principle of rank reduction, direction-of-arrival (DOA) estimates of far-field sources are firstly decoupled under unknown mutual coupling. Then these estimates are employed to generate the mutual coupling coefficients. Finally, by the mutual coupling compensation and the far-field components elimination, near-field sources parameters (DOA and range) are obtained. The proposed algorithm is efficient in that it only requires second order statistics and one dimensional spectral search. Simulation results demonstrate that our algorithm is effective for the classification and localization of mixed sources under unknown mutual coupling.     

空间色噪声环境下双基地MIMO雷达多目标角度估计和互耦自校正

提出了在空间色噪声环境下双基地MIMO雷达多目标角度估计和互耦自校正的算法.利用四阶累积量能抑制空间色噪声的特性,对数据进行预处理.通过互耦系数矩阵的Toeplitz特性和ESPRIT算法思想,分别提取出发射端和接收端的旋转不变因子,并且实现了发射角和接收角的自动配对.最后利用估计出来的发射角和接收角,采用拉格朗日乘数法实现了互耦系数的自校正.仿真结果证明了本文算法的有效性.     

互耦宽带MIMO系统容量分析

研究了宽带通信系统中,互耦现象对多输入多输出（MIMO）通信容量的影响。首先分析了天线阵列间的互耦作用,并基于此推导出互耦条件下宽带通信系统的容量表达式。然后通过蒙特卡洛方法,仿真了不同天线阵列配置下的系统容量。结果表明,在天线阵列间距很近时,天线阵列间的互耦效应能够改善天线阵列之间的相关性,从而提高系统的容量。并且天线数目越多,系统容量改善越大。该结论对宽带MIMO通信系统的天线设计起到一定的指导作用。     

On the design of a reject band filter for antennas mutual coupling reduction

In this article, a novel concept for mutual coupling reduction between antenna elements is proposed at 2.45 GHz for Wi‐Fi applications. A reject band filter (RBF) is used in order to reduce the mutual coupling between two monopoles for multi‐input multi‐output (MIMO) systems. The proposed RBF inclusions are developed to have zero refractive index response over a specific frequency band. The inclusions considered here are composed of open‐loop resonators; each one with the same iteration level of Minkowski‐like pre‐fractal structures coupled with an open‐stub transmission line to increase the band selectivity. The inclusions are inserted between λ/2‐spaced monopole elements at 2.45 GHz. A significant mutual coupling reduction is realized by incorporating only two RBF cells. Such effective response is attributed to the electromagnetic wave cloaking at 2.45 GHz using the developed RBF inclusions. An extensive theoretical study using both numerical and analytical methods is invoked to obtain the best performance of the proposed MIMO antenna structure. Finally, the experimental and numerical results are agreed excellently.     

Investigation on dual‐port printed MIMO antenna with reduced RCS for C‐band radar application

In this communication, two port printed Multi Input Multi Output (MIMO) antenna with reduced radar cross section and low mutual coupling is designed and analyzed. Reduced mutual coupling (less than ?20 dB) is achieved by placing the electromagnetic band gap structure in between the two identical ports. Frequency selective surface has been used to reduce the radar cross section (more than 30 dB reduction) of the proposed antenna design, which makes it suitable for military applications. The proposed radiating design is fabricated and measured for the purpose of validation. It resonates at 6.8 GHz supporting an impedance bandwidth of 1.03 GHz from 6.12 to 7.15 GHz. It promises a gain of 4.75 dB in the working frequency range. This radiator is suitable for military radars works in C‐band.     

2‐D D3LS algorithm with mutual coupling

New adaptive algorithm of direct data domain is presented which can recover the signal in the presence of mutual coupling. The proposed algorithm can estimate the coupling coefficients without utilizing any auxiliary sensors. Numerical simulation shows that the proposed algorithm can accurately recover the signal in the presence of mutual coupling. © 2011 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2011.     

基于SCADA参量关联互信息自编码的风电机组故障检测方法

针对风力发电机组数据采集与监视控制系统(supervisory control and data acquisition,SCADA)监测参量间的耦合关联性,提出基于多参数耦合关联互信息编码的风电机组故障检测方法.该方法构建了SCADA数据的耦合关联矩阵,采用互信息变分自编码器对关联矩阵进行编码重构;将SCADA参量关联矩阵的重构误差作为机组健康评估指标,结合指数加权移动平均模型的迭代更新,对机组实时故障阈值进行自适应设置.两个风场的风电机组SCADA数据分析结果表明,所提方法充分利用了SCADA数据的耦合关联结构信息,能有效提高风电机组故障检测的准确性及对环境工况的鲁棒性.     

Adaptive nulling of a linear dipole array in the presence of mutual coupling

This article proposes a novel mutual impedance matrix model for compensating mutual coupling effects in adaptive array with application to adaptive nulling of interference signals. In the new method, extreme care has been taken into account for both self impedance and mutual impedance, relating to the mutual coupling effects. Numerical simulation results demonstrate the robustness and capability of this technique. By using the new method, it is found that both the accuracy of the positioning and depth of the nulls are significantly improved. Performance comparisons of the new methodology and several other previous techniques via a number of simulation are presented. © 2013 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:30–38, 2014.     

一种基于开方检验的特征选择方法

开方检验是目前文本分类中一种常用的特征选择方法.该方法仅关注词语和类别间的关系,而没有考虑词与词之间的关联,因此选择出的特征集具有较大的冗余度.定义了词语的“剩余互信息”概念,提出了对开方检验的选择结果进行优化的方法.使用该方法可以得到既有很强表征性又有很高独立性的特征集.实验表明,该方法表现良好.     

Decoupling antenna array with X‐shaped strip

Manipulating mutual coupling between antenna array elements is always a critical essential in designing phased arrays. In this article, an X‐shaped strip is applied to decouple a five‐element E‐plane microstrip antenna array, whose adjacent elements' center‐to‐center spacing is only 0.45 λ₀. Simulation and measurement results reveal that the proposed array employing the loaded structure exhibits excellent decoupling capability, as in comparison to the reference array, impedance of every port is well matched, mutual coupling between both adjacent elements and nonadjacent ones is efficiently reduced and radiation patterns of every individual patch are markedly corrected. Besides, when beam scanning is performed, the proposed array is equipped with higher gain and lower SLL. The X‐shaped strip predicts a promising application in phased array and a large‐scale array.     

基于泡沫图像特征和物元可拓模型的锑浮选工况识别

针对锑浮选泡沫图像特征相互耦合、重要度差异显著引起工况难以识别的问题, 提出一种锑浮选工况识别方法. 首先, 在结合敏感性指数与主元分析法选取关键泡沫特征的基础上, 建立物元可拓模型, 通过关联函数计算关键泡沫特征与预设工况类别的关联度; 然后, 引入博弈论, 将层次分析法和熵权法确定的主、客观权重优化融合, 得到泡沫特征的综合权重; 最后, 计算综合关联度, 实现浮选工况的准确识别. 锑浮选工业现场的生产数据验证了所提出方法的有效性.

     

A virtual structure approach to formation control of unicycle mobile robots using mutual coupling

In this article, the formation control problem for unicycle mobile robots is studied. A distributed virtual structure control strategy with mutual coupling between the robots is proposed. The rationale behind the introduction of the coupling terms is the fact that these introduce additional robustness of the formation with respect to perturbations as compared to typical leader–follower approaches. The applicability of the proposed approach is shown in simulations and experiments with a group of wirelessly controlled mobile robots.     

Mutual coupling reduction in wideband dielectric resonator antennas

An effective method for reducing the mutual coupling between wideband dielectric resonator (DR) antennas (DRAs) is proposed by covering the metal on the middle dielectric bridge, the contralateral sides and contralateral upper edges of the DRs. This metal decoupling structure can make the coupled electric fields in the adjacent DR be perpendicular to the electric fields of the excited DR, which produce wideband and high isolation between two adjacent DRAs. Thus, the gain of DRA can be restored. For the structural characteristics, the dielectric bridges can connect the decoupling structure and the dielectric blocks of DRAs with high dielectric constant together on the same substrate by PCB process. Finally, the isolation level of the proposed DRAs can be enhanced from 15.5 to 32.3 dB over the effective frequency range from 10.22 to 13.37 GHz or 26.7%.