Ultra-wideband （UWB） microwave images are proposed for detecting small malignant breast tumors based on the large contrast of electric parameters between a malignant tumor and normal breast tissue. In this study, an...Ultra-wideband （UWB） microwave images are proposed for detecting small malignant breast tumors based on the large contrast of electric parameters between a malignant tumor and normal breast tissue. In this study, an antenna array composed of 9 antennas is applied to the detection. The double constrained robust capon beamforming （DCRCB） algorithm is used for reconstructing the breast image due to its better stability and high signal-to-interference-plus-noise ratio （SINR）. The successful detection of a tumor of 2 mm in diameter shown in the reconstruction demonstrates the robustness of the DCRCB beamforming algorithm. This study verifies the feasibility of detecting small breast tumors by using the DCRCB imaging algorithm.展开更多
In order to obtain the robust high-resolution beamforming, a high order cross sensor processing(CSP) approach is developed. According to the relation ship between the target bearing and the phase difference of each el...In order to obtain the robust high-resolution beamforming, a high order cross sensor processing(CSP) approach is developed. According to the relation ship between the target bearing and the phase difference of each element receiving signal, this method exploits the property that the same diagonal of covariance matrix with the same phase difference and obtains(2M-1)(N-1)virtual elements(N is the original array number) by executing M order CSP. The extended virtual elements can effectively increase the physical aperture of linear array, reduce the main lobe width of beam-forming, and improve the bearing resolution. The CSP method accumulates the data on the same sub-diagonal of the covariance matrix, which can decrease the impact of background noise on beam-forming. The theoretical analysis and experimental results both show that this method has high resolution in bearing estimation, compared with the MUSIC method, which has better robustness under the lower signal-to-noise ratio(SNR).展开更多
针对现有超宽带穿墙雷达时域波束成像分辨率低、旁瓣高以及干扰抑制能力弱等问题,提出利用稳健Capon波束形成对目标成像的方法。该方法基于目标回波模型首先补偿近场扩散损耗、墙体传播损耗和折射效应,实现天线阵列接收数据的配准,利用...针对现有超宽带穿墙雷达时域波束成像分辨率低、旁瓣高以及干扰抑制能力弱等问题,提出利用稳健Capon波束形成对目标成像的方法。该方法基于目标回波模型首先补偿近场扩散损耗、墙体传播损耗和折射效应,实现天线阵列接收数据的配准,利用稳健Capon波束成像得到良好的成像分辨率和更好的干扰抑制能力。利用时域有限差分(finite-difference time domain,FDTD)数值仿真和实验数据实现了隐藏目标的二维成像,验证了该方法的有效性。展开更多
当阵列误差存在时,Capon波束形成算法性能会急剧下降,特别是阵列输出信干噪比(signal to interfer-ence plus noise ratio,SINR)。对角加载可以减弱小特征值对应的噪声波束的影响,能有效改善阵列性能及方向图畸变,但加载值的确定是一个...当阵列误差存在时,Capon波束形成算法性能会急剧下降,特别是阵列输出信干噪比(signal to interfer-ence plus noise ratio,SINR)。对角加载可以减弱小特征值对应的噪声波束的影响,能有效改善阵列性能及方向图畸变,但加载值的确定是一个较为困难的问题。该算法根据加载值和采样协方差矩阵间的关系确定加载值,能自适应地根据采样数据确定加载值,在小快拍数和阵列误差存在情况下仍具有良好的鲁棒性,明显改善了阵列性能并减小了方向图畸变,且使零陷准确对准干扰方向。计算机仿真结果证实了此算法的鲁棒性。展开更多
基金supported by the National Natural Science Foundation of China (Grant No. 61271323)the Open Project from State Key Laboratory of Millimeter Waves, China (Grant No. K200913)
文摘Ultra-wideband （UWB） microwave images are proposed for detecting small malignant breast tumors based on the large contrast of electric parameters between a malignant tumor and normal breast tissue. In this study, an antenna array composed of 9 antennas is applied to the detection. The double constrained robust capon beamforming （DCRCB） algorithm is used for reconstructing the breast image due to its better stability and high signal-to-interference-plus-noise ratio （SINR）. The successful detection of a tumor of 2 mm in diameter shown in the reconstruction demonstrates the robustness of the DCRCB beamforming algorithm. This study verifies the feasibility of detecting small breast tumors by using the DCRCB imaging algorithm.
基金supported by the National Natural Science Foundation of China(61372180)the Young Talent Frontier Project of Institute of Acoustics of Chinese Academy of Sciences(Y454341261)
文摘In order to obtain the robust high-resolution beamforming, a high order cross sensor processing(CSP) approach is developed. According to the relation ship between the target bearing and the phase difference of each element receiving signal, this method exploits the property that the same diagonal of covariance matrix with the same phase difference and obtains(2M-1)(N-1)virtual elements(N is the original array number) by executing M order CSP. The extended virtual elements can effectively increase the physical aperture of linear array, reduce the main lobe width of beam-forming, and improve the bearing resolution. The CSP method accumulates the data on the same sub-diagonal of the covariance matrix, which can decrease the impact of background noise on beam-forming. The theoretical analysis and experimental results both show that this method has high resolution in bearing estimation, compared with the MUSIC method, which has better robustness under the lower signal-to-noise ratio(SNR).
文摘针对现有超宽带穿墙雷达时域波束成像分辨率低、旁瓣高以及干扰抑制能力弱等问题,提出利用稳健Capon波束形成对目标成像的方法。该方法基于目标回波模型首先补偿近场扩散损耗、墙体传播损耗和折射效应,实现天线阵列接收数据的配准,利用稳健Capon波束成像得到良好的成像分辨率和更好的干扰抑制能力。利用时域有限差分(finite-difference time domain,FDTD)数值仿真和实验数据实现了隐藏目标的二维成像,验证了该方法的有效性。
文摘当阵列误差存在时,Capon波束形成算法性能会急剧下降,特别是阵列输出信干噪比(signal to interfer-ence plus noise ratio,SINR)。对角加载可以减弱小特征值对应的噪声波束的影响,能有效改善阵列性能及方向图畸变,但加载值的确定是一个较为困难的问题。该算法根据加载值和采样协方差矩阵间的关系确定加载值,能自适应地根据采样数据确定加载值,在小快拍数和阵列误差存在情况下仍具有良好的鲁棒性,明显改善了阵列性能并减小了方向图畸变,且使零陷准确对准干扰方向。计算机仿真结果证实了此算法的鲁棒性。
