共查询到20条相似文献,搜索用时 171 毫秒
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采用有限元方法研究二维混波室结构辐射电流和测量的辐射场平均值的关系,目的是了解混波室测量环境是否能够满足电磁兼容辐射测量的要求.从二维数值计算结果可以看到,观测场的平均值和辐射电流具有很好的线性关系,从而证明混波室可以作为电磁兼容辐射测量的一个有效测试设备. 相似文献
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无线移动信道由于电波在移动信道中时域与空域上传输时,有很大的随机波动与起伏的特点,控制与测量一般难以把握,通过数值计算与路径损耗建立模型与仿真,能够较好地预知信道特性。根据无线移动信道模型特征建立无线移动信道模型,然后对自由空间模型、经验模型Okumura-Hata模型、COST-231 Hata模型以及COST231-WI模型进行了建模与仿真,并将对仿真结果进行了分析,为无线移动通讯信道传播模型选择提供参考。 相似文献
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研究了UWB通信系统的Scholtz室内信道传播模型,进行了信道仿真,仿真结果具有明显成簇现象,与已公布的UWB信道实测结果具有很好的相似性。同时,研究了UWB通信系统的另3种信道传播模型,S—V信道模型、IEEE802.15.3a信道模型和AT&T信道模型,进行了信道仿真,得到了特征参数。并将Scholtz信道在3种不同房间中的传播特性以及各信道模型在同样的环境中进行了比较。为UWB系统在不同的信道模型上得到的分析值之间的转化提供参考。 相似文献
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本文对家用平板微波炉和混波室的结构和应用进行了对比并提出在微波炉性能改善的工作中可以借鉴混波室的设计方法。在此基础上对多搅拌片和不规则形状的腔体进行了设计和验证。两种方法的验证结果相对传统的微波炉结构的微波加热均匀性都有明显的提升,表明混波室为形成统计均匀的电磁场的设计方法可应用于微波炉加热均匀性改善。 相似文献
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针对战术通信模拟训练无线信道建模与仿真的需要,设计了基于HLA的无线信道模型与仿真框架及其仿真流程。研究分析了由天线模型、连通判断模型、时延计算模型、传输模型、接收功率模型、干扰功率模型、信噪比模型组成的无线信道及其干扰模块,此模型较好地对战术通信无线信道情况进行描述,并拥有良好的扩展性和可移植性。 相似文献
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A new way to experimentally simulate propagation channels between antenna arrays using coupled mode-stirred reverberation chambers is presented. This technique, which can be performed in a laboratory facility, is simple to use and allows the easy modification of the channel characteristics. 相似文献
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为了提高盲源分离(blind source separation, BSS)算法在混响和噪声环境下的鲁棒性,提出了一种适用于欠定情况下用于卷积混合信号的盲源分离算法。在该算法中,利用高混响环境下混合模型即使在时频(time-frequency, TF)域中仍具有卷积特性,并结合房间冲激响应(room impulse response, RIR)的统计规律,将时频域中的瞬时模型扩展到更适合高混响环境的卷积模型,进而构建一欠定盲源分离优化问题,最后,采用交替方向乘子法(alternating direction method of multipliers, ADMM)优化框架来求解该问题。仿真实验结果表明:在混响环境下,本文提出的基于卷积模型的盲源分离算法与现有盲源分离算法相比,具有非常明显的性能优势。 相似文献
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A closer look at reverberation Chambers - 3-D Simulation and experimental verification 总被引:4,自引:0,他引:4
This paper presents three-dimensional (3-D) full-wave simulations of the electromagnetic field inside a medium-sized reverberation chamber. A frequency-domain method-of-moments approach based on the electric field integral equation is used. A synopsis of the computational challenges particular for reverberation chambers is described and a detailed overview on the chamber modeling procedure is given. The electric field inside the chamber is computed and the influence of small geometric details and asymmetries is investigated as well as the effect of different excitations and stirrers. It is demonstrated that a statistics-based validation of reverberation chamber simulations is insufficient. To validate simulation results, therefore extensive near-field measurements inside the prototype reverberation chamber are performed. The complete 3-D reverberation chamber simulation, considering stirrers, door, and various practical excitations, accurately predicts the fields within the chamber in the important lower-to-medium frequency range and thus represents a reliable tool facilitating reverberation chamber optimization. 相似文献
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A computer model has been developed that simulates charge transport of carriers in a surface channel charge-coupled device. This model is based on the charge continuity and current transport equations with a time dependent surface field. The device structure of the model includes a source diffusion an input gate and transfer gate. The present model is the first real simulation of the input scheme of the surface-channel CCDs. The scooping and spilling techniques associated with the charge injection process are simulated by the input diffusion which is included in the model.As an application to a CCD practical problem the present model has been used to study the linearity of the electrical charge injection into surface channel charge-coupled devices. The generated harmonic components of a sinusoidal input are calculated using the transfer characteristics of the input stage obtained from the computer simulation.Using this model the spatial variations of the self-induced fringing field and total currents under the storage and transfer gates were computed. The charge transfer mechanisms for short-gate (L ≤ 8 μm) CCDs was investigated. It was found that for short gates the charge transfer efficiency is governed mainly by the fringing field and self-induced current mechanisms. The results of this study help to clarify the mechanism by which the signal-charge level and gate length affect the charge transfer efficiency. 相似文献
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A major problem for active sonar systems operating in shallow water is reverberation. High time-bandwidth waveforms and coherent matched filtering are often used to improve detection performance in reverberation. However, an active sonar echo undergoes distortion during the two-way propagation and reflection from the target. As a result, the full performance gain is not achievable, and this approach is severely limited. In this case, more robust detectors are needed. We evaluate the detection performance of several commonly used detectors in an ideal nondistorting channel, a fast-fading distortion (FFD) channel, and a channel with time-spreading distortion (TSD). We examine the robustness of the various detectors by evaluating the performance in the case of mismatch between the detector and the channel parameters. Studying the relation between the FFD model and the TSD, we show that, under certain conditions, the TSD and FFD channels have an equivalent effect on the waveform 相似文献