A novel design using meshed-planar fan-electromagnetic bandgap (MP-FEBG) structure for ultra-wideband (UWB) antenna

A concept to combine the plane fan antenna with the meshed-planar electromagnetic bandgap (MP-EBG) structure is proposed; and then, based on the theory, a novel ultra-wideband (UWB) antenna with double-deck meshed-planar fan-electromagnetic bandgap (MP-FEBG) is designed. The structure of the sector is beneficial to the increase of the antenna bandwidth. The double layer structure can greatly reduce the size of the antenna, and the aperture structure can easily adjust antenna's performance. The antenna is compact in size, suitable for UWB applications. An antenna model was established on the substrate of FR4 and at least 79.1% dimension of the antenna was reduced by the traditional UWB antenna in the related documents. The simulation results show that the antenna can achieve a wide bandwidth from 3.20 to 15.78 GHz with return loss less than −10 dB and exhibit stable antenna gain. Furthermore, the measurement result is in better consistence with the simulation result.     

Ultra-wideband water-based metamaterial absorber with temperature insensitivity

The natural water has frequency dispersion and its permittivity is also related to temperature, which are important factors to design temperature insensitive absorber at microwave frequency. Here, a water-based metamaterial absorber which is fabricated by 3D-printing is proposed. The absorber can perform stably at different temperatures and it also shows 90% absorption in the frequency range of 7.9–21.7 GHz. The experiment proves that the absorber can work at a wide incident angle and is polarization insensitive. Based on these features, the water-based absorber could be applied to various electromagnetic scenarios such as stealth technology and electromagnetic compatibility in temperature-variable environment.     

A High-Power Reflector Impulse Antenna with Dual-Tem Source

There are different demands on radiation efficiency and direction pattern according to various ultra-wideband (UWB) antennas and high power applications. To obtain more radiating gain on bore-sight of paraboloidal reflector and centralized radiating direction, a novel feeding structure called dual-TEM source has been designed and applied in half-paraboloidal reflector impulse radiating antenna (IRA) applications. Simulation results proved that this proposed half-paraboloidal reflector IRA with dual-TEM source provided greater radiation performance on bore-sight as a result of the synthesized power in the aperture space of paraboloid. Moreover, lots of simulation work and comparison have been done in different feeding models to summarize a relative optimal feeding structure.     

Wu-King 加载偶极天线的FDTD分析

 用时域有限差分法分析了高斯脉冲激励的Wu-King加载偶极天线的特性。给出了天线周围空间瞬态场的变化情况及天线上的电流波形，这种形象化的结果为加载脉冲辐射天线的设计和改进提供了直观的物理依据。通过时域远近场变换，得到了天线脉冲辐射远场。计算并给出了描述脉冲辐射器性能的时域参数：保真度和能量方向图。     

重构-等效啁啾分布反馈半导体激光器的多信号直调特性

在测量与分析频率响应与动态范围的基础上,研究了重构-等效啁啾分布反馈半导体.直调激光器偏置电流以及调制信号的微波功率对直调结果的影响.将300Mb/s基带信号与1.562 5Gb/s超宽带信号同时直接加载到该激光器上,经过10km单模光纤传输后进行波形、频谱及误码率的检测,结果表明:基带信号与超宽带信号的功率代价分别为1.98dB与0.92dB;该激光器具有良好的多信号直接调制性能,在基于波分复用无源光网络的多业务融合网络中具有重要的应用前景.     

Photonic generation of millimeter-wave ultra-wideband signal using microfiber ring resonator

The photonic generation of millimeter-wave (MMW) ultra-wideband (UWB) signal using microfiber ring resonator (MRR) is proposed. The central frequency and 10-dB bandwidth of generated MMW-UWB signal varying with Q factor of MRR are analyzed. We successfully demonstrate a generation of 24-GHz MMW-UWB signal by utilizing a microfiber ring resonator with free spectrum range of 20 GHz and Q factor of 19,000. The generated MMW-UWB signal has a power spectrum density complying with Federal Communication Committee requirements.     

TEM喇叭超宽带接收特性分析

 采用时域有限差分（FDTD）和离散傅里叶变换（DFFT）相结合的方法计算了不同长度及不同张角TEM喇叭接收天线的传递函数及灵敏度，采用最大相对误差和相对平均偏差分析了TEM喇叭超宽带接收的波形保真性与其几何尺寸之间的关系。分析结果表明：在设计高灵敏度及高波形保真性的超宽带TEM喇叭脉冲测量天线时，对TEM喇叭的张角和长度应进行折衷考虑。     

微波孔缝线性耦合函数研究

讨论了微波脉冲通过孔缝线性耦合进入腔体内的研究方法。给出了线性耦合的物理基础,定义了耦合函数，并导出了耦合函数随入射电场极化方向变化的公式。简要描述了数值求解孔缝线性耦合的时域有限差分方法以及修正算法。给出了以矢量网络分析仪HP8510C为主要设备测量耦合函数的实验方法。通过耦合函数的研究，观察到了共振效应和增强效应等现象，给出了微波孔缝耦合发生共振的普适公式。分析了测量探头对耦合函数测量的影响，验证了耦合函数随入射电场方向变化的公式。理论、数值和实验结果符合得较好。     

宽波束双馈源超宽带抛物面天线设计与仿真

 针对单馈源超宽带抛物面天线波束较窄的问题，设计了一种宽波束双馈源超宽带抛物面天线。该抛物面天线是由一个普通的抛物面从中间对称分式，并在中间以平板连接而成的。馈源采用改进型平面TEM喇叭天线，同轴垂直馈电方式。两个馈源分别置于抛物面的两个焦点上。并利用时域有限差分数值方法分析了该天线的辐射性能。通过改变抛物面的结构，调节双馈源与天线主轴的夹角等方法可以有效改善天线的辐射性能。结果表明，所设计的宽波束双馈源抛物面天线可以在远区更宽的空间上形成峰值功率比较均匀的电磁脉冲，在不降低峰值功率的前提下有效地增加了波束的宽度；在抛物面天线两边进行少量切割不会对辐射场产生明显影响，节省了空间。     

Design and Simulation of a Wide-Beam High-Power Parabolic Antenna with Dual-Source

For resolving the essential problem that the beam is too narrow in the application of the high-power UWB (Ultra-Wideband) antenna with single-source, a novel wide-beam high-power parabolic antenna with dual-source has been designed, and the edge of the paraboloid was cut in order to reduce the size of the antenna. Radiation properties of this proposed antenna are studied with finite-difference time-domain (FDTD) numerical method. The radiation properties of the proposed antenna can be improved by changing the structure of the parabolic antenna and adjusting the angle between the source and the axis of the antenna. The result shows that the beam-width has been improved significantly under the precondition of maintaining the peak power, and also the size of the antenna was minished by cutting the edge of the paraboloid.