共查询到20条相似文献,搜索用时 31 毫秒
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三维收发(T/R)组件具有小型化、重量轻和可扩充等特点,成为T/R组件技术的重要发展方向之一。本文对一种基于低温共烧陶瓷(LTCC)的Ku波段小型化三维T/R组件进行了研究,通过分析优化组件的垂直微波互连技术、电路布局优化及无源等效模型,设计出具有优良电性能(输出功率≥24.5 dBm,接收增益大于≥25 dB,接收噪声系数≤3.5 dB)的小型化三维T/R组件。该组件利用LTCC高密度布线、球栅阵列(BGA)高密度连接优点,把组件设计成三层层叠结构,并且把部分芯片集成于“多功能芯片”,进一步缩小了尺寸,单个组件尺寸为9.5 mm×9.5 mm× 3.8 mm,有效实现了T/R组件的小型化。 相似文献
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《IEEE transactions on medical imaging》2009,28(7):1051-1061
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A spectral-element time-domain (SETD) method is proposed to solve 3-D transient electromagnetic problems based on Gauss-Lobatto-Legendre polynomials. It has the advantages of spectral accuracy and block-diagonal mass matrix. With the inexpensive inversion of the block-diagonal mass matrix, the proposed method requires only a trivial sparse matrix-vector product at each time step, thus significantly reducing CPU time and memory requirement. Galerkin's method is used for spatial discretization, and a fourth-order Runge-Kutta scheme is employed for the time integration. The perfectly matched layer (PML) is employed to truncate the boundary in unbounded problems. The pseudospectral time-domain method is used to simplify the treatment of the PML inside the proposed SETD method. Numerical examples are shown to verify the efficiency and the spectral accuracy with the order of basis functions 相似文献
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《Antennas and Propagation, IEEE Transactions on》2009,57(11):3655-3663
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圆迹SAR(CSAR)因其特殊曲线运动轨迹而具备3维成像能力。单圈CSAR理论上可以获得距离方位平面亚波长级的分辨率,但是高程向分辨率却很低。同时,利用后向投影(BP)算法进行CSAR 3维成像的算法复杂度高,成像效率低。该文提出一种基于改进3维后向投影的多圈CSAR相干3维成像方法,针对现有成像算法时间复杂度高的问题,提出一种构造几何插值核的CSAR改进3维后向投影算法,可将3维插值操作转化为1维插值操作和距离向量搜索操作,通过多圈CSAR改进3维后向投影成像结果相干积累的方式得到最终3维图像。该文所提方法可有效解决单圈CSAR 3维成像高程向分辨率低的问题,改善3维成像细节,同时能够大幅降低CSAR 3维成像时间。仿真圆锥目标和美国空军实验室GOTCHA数据3维成像结果验证了该文所提方法的有效性。
相似文献7.
Joon-Ho Lee Jiefu Chen Qing Huo Liu 《Antennas and Propagation, IEEE Transactions on》2009,57(9):2666-2674
A discontinuous spectral element time-domain method is proposed to analyze transient electromagnetic properties of general 3-D structures. This method is advantageous in that its mass matrices are block-diagonal due to the Gauss-Lobatto-Legendre polynomials, and it allows different orders of basis functions for each subdomain. The Riemann solver is employed in the boundary integral terms to communicate fields between adjacent subdomains. Perfectly matched layers are utilized to truncate the computational domain. Galerkin method is used for spatial discretization, and a fourth-order Runge-Kutta scheme is employed for the time integration. The validity of the proposed approach is demonstrated through several numerical examples of initial value problems and scattering problems. 相似文献
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圆迹SAR(CSAR)因其特殊曲线运动轨迹而具备3维成像能力.单圈CSAR理论上可以获得距离方位平面亚波长级的分辨率,但是高程向分辨率却很低.同时,利用后向投影(BP)算法进行CSAR 3维成像的算法复杂度高,成像效率低.该文提出一种基于改进3维后向投影的多圈CSAR相干3维成像方法,针对现有成像算法时间复杂度高的问题,提出一种构造几何插值核的CSAR改进3维后向投影算法,可将3维插值操作转化为1维插值操作和距离向量搜索操作,通过多圈CSAR改进3维后向投影成像结果相干积累的方式得到最终3维图像.该文所提方法可有效解决单圈CSAR 3维成像高程向分辨率低的问题,改善3维成像细节,同时能够大幅降低CSAR 3维成像时间.仿真圆锥目标和美国空军实验室GOTCHA数据3维成像结果验证了该文所提方法的有效性. 相似文献
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《Microwave Theory and Techniques》2009,57(8):2015-2020
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A emthod of 2-D Fourier transform used in 3-D surface profilometry is proposed,analyzed and compared with 1-D Fourier transform method in theory and practical measuring result.It was proved that the 2-D Fourier transform method has more advantages over 1-D Fourier transform methodd in biggest crook-rate limits,accuracy and sensitivity of measuring.Styudy on measuring object surface details with large crook-rate changing accurately used new higher-power index low-pass filter of spatial frequency domain.A new method of automatic produced reference grating image and error-correcting is proposed.One undeform row of deform grating image is used to extend a complete reference grating image,and some error-correcting method is used to process the result to get accurate surface shape and the deflection of reference surface normal line deviated from the axle of camera.By this new method,one deform rectangle grating image is only used to get the 3-D shape accurately. 相似文献
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《Microwave and Wireless Components Letters, IEEE》2009,19(2):62-64
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A controller that produces sculptured surfaces from a small input without postprocessing is presented. It generates straight lines, circular arcs, and algebraic and trigonometric curves in any plane or combinations of such forms to produce complex lines and surfaces for machining applications. The controller is very versatile and can reduce programming costs by orders of magnitude 相似文献
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Tian Xiao Qing Huo Liu 《Antennas and Propagation, IEEE Transactions on》2008,56(3):765-773
In this paper, we present an enlarged cell technique (ECT) to avoid the time step reduction encountered in the conformal finite-difference time-domain (CFDTD) method due to small irregular cells truncated by metallic boundaries. We focus our efforts on the discussion of the accuracy and stability of the ECT and its comparison with other conformal methods, especially the one called the uniformly stable conformal (USC) method. We also provide a simplified ECT, which is much easier to implement. In the ECT, a stability criterion is first constructed to identify instable irregular cells, i.e., those having so small an area to cause instability. Those instable cells are then enlarged into their adjacent cells to obtain a large, stable area. Careful treatment is performed on the communication between the intruding and intruded cells in terms of electromotive force by keeping the total electromotive force conservative. This technique is verified by several 3-D numerical experiments. Results show that the ECT is second-order accurate and numerically stable at the regular Courant time step limit. 相似文献
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《Signal Processing, IEEE Transactions on》2009,57(2):551-564
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Eng Leong Tan 《Microwave and Wireless Components Letters, IEEE》2007,17(11):748-750
A concise current source implementation is presented for the unconditionally stable 3-D alternating direction implicit finite-difference time-domain (ADI-FDTD) method. Unlike the conventional implicit symmetric source scheme applied in both updating procedures, the new implementation involves implicit current formulation in the first procedure only. Note however that the resultant accuracy does not deteriorate but remains to be identical as before. This is achieved using our recent efficient algorithm for the 3-D ADI-FDTD method. Moreover, the current formulations applied in both procedures therein are simplified, along with further reduction of the floating point operations count for the main iterations. Analytical validation of the equivalence among conventional implicit symmetric source scheme and our efficient algorithms with alternative current implementations are discussed. Numerical results provide closer scrutiny of the asymmetry errors, which may still exist even with symmetric source. 相似文献
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基于莫尔条纹的三维物体相关识别 总被引:4,自引:0,他引:4
提出了一种新的基于莫尔条纹的三维物体识方法。用阴影莫尔法的装置,采用频域滤波的方法,得到物体的莫尔条纹。用受到物体表面高度调制的莫尔条纹图作为输入图像,用光学匹配空间滤波的概念来实现相关识别方法,根据输出的相关峰值大小即可判别不同的物体。因为物体的莫尔条纹是物体的等高线,体现三维物体特征的高度函数以莫尔等高线的形式编码于莫尔条纹中,因此基于莫尔条纹的相关识别具有本征三维识别的特点。计算机模拟试验结果证明了这种方法用于三维物体识别的可能性。 相似文献