伴随着6G 通信的发展，雷达遥感、检测成像等多个领域向太赫兹频段拓展，获取材料在该频段的介电常数显得愈发重要。本文基于NR 迭代法提取了太赫兹频率下样品的复介电常数，分析了迭代法的初值选取对提取结果的影响。在325~500 GHz 频段(Y 频段)搭建了一套由矢量网络分析仪(VNA)、扩频模块和四抛物面镜组成的8f 准光系统，实现散射参数S 2 1 的自由空间测量。由电磁波传输模型推导出复介电常数与S 2 1 之间的关系式， 利用迭代法提取出了特氟龙(Teflon)、丙烯腈-丁二烯-苯乙烯共聚物(ABS)和聚甲基丙烯酸甲酯(PMMA)样品的复介电常数谱，与其他文献报道的结果一致，验证了系统和方法的有效性。

In this study, carbon black (CB) powder-loaded polyurethane (PU) composites (CB–PU composites) were prepared by melt mixing method with different volume percentages (45, 50, 55, 58 and 61 vol.%) of CB in the PU matrix. The prepared CB–PU composites had been further studied for surface morphology using the field-emission scanning electron microscopy (FESEM) technique. Dielectric properties in terms of real permittivity (𝜀′) and imaginary permittivity (𝜀′′) of the fabricated composites were computed using an Agilent E8364B vector network analyzer in the frequency range of 8–12 GHz (X-band). Dielectric loss factor of the prepared CB–PU composites was computed in terms of the dielectric loss tangent (tan δe = 𝜀′′/𝜀′). Microwave absorbing properties were appraised in terms of the reflection loss (RL) which in turn was calculated for varying thicknesses of the prepared composites from the measured real and imaginary permittivity data. The minimum RL was observed as −20.10 dB for the absorber with a thickness of 2.2 mm and the bandwidth achieved was 1.92 GHz for RL ≤−10 dB. Based on the above results these CB–PU composites have potential use as effective microwave absorbers in 8–12-GHz (X-band) frequency range.In this study, carbon black (CB) powder-loaded polyurethane (PU) composites (CB–PU composites) were prepared by melt mixing method with different volume percentages (45, 50, 55, 58 and 61 vol.%) of CB in the PU matrix. The prepared CB–PU composites had been further studied for surface morphology using the field-emission scanning electron microscopy (FESEM) technique. Dielectric properties in terms of real permittivity (𝜀′) and imaginary permittivity (𝜀′′) of the fabricated composites were computed using an Agilent E8364B vector network analyzer in the frequency range of 8–12 GHz (X-band). Dielectric loss factor of the prepared CB–PU composites was computed in terms of the dielectric loss tangent (tan δe = 𝜀′′/𝜀′). Microwave absorbing properties were appraised in terms of the reflection loss (RL) which in turn was calculated for varying thicknesses of the prepared composites from the measured real and imaginary permittivity data. The minimum RL was observed as −20.10 dB for the absorber with a thickness of 2.2 mm and the bandwidth achieved was 1.92 GHz for RL ≤−10 dB. Based on the above results these CB–PU composites have potential use as effective microwave absorbers in 8–12-GHz (X-band) frequency range.

为解决微波激发等离子体参数诊断存在的困难问题，提出利用二端口传输反射法测量微波激励产生的低温等离子体的等效相对复介电系数。使用有限元方法设计了基于BJ22标准波导的样品测试结构，该 结构能在较大的介电系数范围内，保证介电系数和端口的|S11|,φS11和|S21|参数保持较好的单调性，避免产生多值问题；通过人工神经网络对计算获得的各介电系数对应的S参数进行训练，达到足够的精确度；最后 通过实验，将测量获得的S参数利用神经网络反演获得待测物质的相对复介电系数。该方法对今后测量类似等离子体、复介电系数实部为负的特殊材料的介电常数具有一定的指导意义。

沙尘对激光信号的散射和吸收作用会引起激光信号的严重衰减, 本文结合我国沙尘粒子的半径分布特征, 在考虑含水影响的基础上, 研究了沙尘对激光信号衰减特性的影响, 得到了接收端信噪比的表达式；同时针对OOK调制, 推导了沙尘天气下激光通信系统的误码率和信道容量。仿真分析了能见度、传输距离、含水量以及激光波长等因素对误码率和信道容量的影响。结果表明：随着含水量和传输距离的增大以及大气能见度的减小, 系统的误码率会呈现出不断增大的趋势, 而信道容量则呈现减小的趋势。在能见度为4 km的情况下, 波长为1 550 nm、传输距离为1 km时系统的误码率可达10-2数量级, 且归一化信道容量为8.48 bps/Hz。

微波对物质的加热涉及电磁、热、加热物的物理参数随温度变化等多种物理过程的综合作用。研究耦合电磁场、热传导和被加热物质物理参数方程构建多物理场方程组, 数值求解获得微波加热过程的温度变化。给出多物理场算法公式和计算流程, 以 2.45 GHz微波加热水为例, 多物理场仿真了该加热过程的微波功率分布、热量累积和温度上升, 设计和加工制作了微波加热实验装置。在工作频点 2.45 GHz处, 测试装置的回波损耗为 16.2 dB, 同时测试了输入功率 40 W时4个指定点处 60 s内的温升, 多物理场仿真结果与测试结果吻合良好, 验证了多物理场仿真的正确性。

研究了固体有机样品的太赫兹介电谱与组分体积含量之间的关系。通过分析有效介质理论中的 CRI(Complex Refractive Index)模型, 得到样品的介电参数与组分体积含量的关系式。利用太赫兹时域光谱技术测得室温下两种氨基酸样品在 0.5～2.7 THz的介电性质, 样品的折射率、介电系数及介电损耗均随氨基酸体积含量增加而增大。选取氨基酸介电损耗谱特征峰位处的介电参数, 根据 CRI模型进行拟合, 得到折射率与体积含量的线性关系式, 介电系数和介电损耗与体积含量的二次函数关系式。研究结果有利于扩展太赫兹波段的定性定量分析手段, 并对聚合物基复合材料制备有一定参考意义。

采用带法兰结构的TE01n圆柱谐振腔，用无损检测的方法测量薄板型微波介质材料的复介电常数。利用轴向模式匹配法对谐振腔内的电磁场进行了求解，给出了相对介电常数和损耗角正切的计算公式，并利用矢量网络分析仪对几种常用微波介质材料进行了测量，其结果表明：该测量方法对相对介电常数的测量误差不超过1%，而对损耗角正切的测量误差不超过10%。该方法还具备一腔多模的测试能力，测量频率可调，可用于介质材料频率特性的测量。

介绍了材料复介电常数测量方法的研究进展,包括理论基础,发展过程,以及最新的应用。其中主要以谐振法,传输反射法,自由空间法为研究对象,就各类方法的优缺点与适用情况进行分析,也简要介绍了时域测量法。

提出了一种基于闭式谐振腔TM_0mn模式测量微波介质材料复介电常数的方法。利用模式匹配技术、Ritz-Galerkin方法以及传输模品质因数测量法导出了介质材料相对介电常数和损耗角正切的测量公式。最后,利用矢量网络分析仪对常用天线罩材料进行了扫频测量,结果表明:高分子量聚乙烯在3~6 GHz范围内的相对介电常数为2.30±0.05,损耗角正切为(1.8~2.0)×10-4。