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In large antenna arrays, the possibility of occurrence of faults in some of the radiating elements cannot be precluded at all times. In such situations, the radiation pattern of the array gets distorted, mostly with an increase in sidelobe level and decrease in gain. Although it is not possible to restore the pattern fully by rearranging the excitations of the functioning elements, compensation methods have been reported in the literature for restoring one performance parameter of the array and making a trade‐off on some other parameter. In this article, we have made a study on the tolerance level of this compensation process. One part of the study deals with the thinning in the failed array, that is, to find a limit on the minimum number of functioning elements of the array that can restore the digital beamforming of the failed array. The second part of study deals with finding the maximum number of element failures that can be compensated. The study was carried out by optimizing the amplitude excitations of the failed array. Instead of classical optimization techniques, particle swarm optimization was used for the compensation process. © 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:635–645, 2014. 相似文献
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In this paper, a broadband dielectric resonator antenna (DRA) with a simple H‐slot feeding structure is proposed. The broad bandwidth (~45%) and uni‐directional radiation enable this DRA suitable to work as a radiation element in the construction of a beam‐scanning array with not only low frequency sensitivity which is important for accurate angle estimation of in‐coming targets, but also a wide scanning range. Moreover, stable coupling coefficients are established around all the above three resonances with respect to its corresponding feeding line, ensuring a low sidelobe level (SLL) across the whole operating frequency range. In order to realize such a DRA, a latticed rectangular structure is utilized to generate the lower two resonances, while the upper resonance is generated by its H‐shaped feeding slot. The shape of the latticed dielectric resonator is also modified according to a 3‐D printed fixing structure for an accurate installation. A 20‐element beam‐scanning prototype is demonstrated and manufactured. The range of scanning angle is from ?36° to +13° within the bandwidth of 10 to 16 GHz, corresponding to a frequency sensitivity of only 122.5 MHz/o. The achieved SLL are smaller than 19 dB for all scanning beams. The above performance indicates that, this array is very suitable for near‐range radar systems requiring an accurate angle estimation. 相似文献
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针对广义旁瓣相消器(Generalized sidelobe canceller,GSC)存在非相干噪声消除性能不佳的缺陷,提出了采用后置Kalman滤波器改进的GSC去噪算法。该算法通过归一化最小均方算法校正自适应噪声对消器,并将滤除方向性干扰噪声后的语音信号输出到Kalman滤波器中,对残余背景噪声进行迭代最小均方误差(Minimum mean square error,MMSE)估计,抑制非相干噪声与麦克风阵元所产生的热噪声。经过在不同信噪比条件下客观语音质量评估(Perceptual evaluation of speech quality,PESQ)及语谱图分析后证明,与传统的GSC以及后置谱减法的改进GSC相比,本算法在噪声消除上的表现更为优越,且增强后信号也更接近目标信号。 相似文献
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一种低副瓣锐截止波束赋形阵列天线设计 总被引:1,自引:0,他引:1
采用联合DFP和BFGS变尺度,结合全局寻优算法,通过优化阵列各单元馈电幅度和相位分布,设计了一种满足低副瓣锐截止波束赋形要求的阵列天线.该阵列由26个印刷振子单元天线组成,各单元馈电电路采用带状线环形桥.馈电电路网络采用带状线结构,整个馈电网络和印刷天线采用一体化设计,具有插入损耗小,结构紧凑的特点.实测表明,3dB波束宽度为11°,水平面锐截止为5.83dB/(°),副瓣低于-20dB.天线设计满足指标要求,并已获得应用. 相似文献
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Based on the existing method of iterative Fourier transforms, an adaptive iteration Fourier technique (AIFT) is proposed for antenna arrays synthesis. Compared with the initial method, three different aspects exist in AIFT. Firstly, the method could adaptively compute the peak sidelobe threshold(PST) in order to obtain the optimum distribution of element excitations satisfying the objective parameter. Secondly, un-uniform element excitations are employed to meet the requirement of sidelobe reduction. Thirdly, when the antenna arrays were massively truncated, the method could lower the beamwidth of their far field patterns by adaptively modulating the value of array factors that are located in the edge region of mainlobes so that the beam broadening caused by the initial method could be efficiently avoided. Simulation results for different design requirements show the effectiveness and high efficiency of the proposed method. 相似文献
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超低副瓣相控阵天线设计中的几个问题 总被引:8,自引:0,他引:8
本文论述了超低副瓣相控阵天线的设计方法,它涉及诸多因素,这里主要研究诸如阵列单元互耦,单元与馈电系统之间的传输变换段,阵列激励与位置误差,以及单元通道校准问题。 相似文献
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