光生等离子体菲涅尔波带板天线

本文描述一种光生等离子体菲涅尔波带板天线的设计方法.利用中心波长为808 nm的近红外激光器阵列通过光学掩膜(菲涅尔波带板的照相底片)照射高电阻率的硅片,使硅片呈现出菲涅尔波带板的衍射特性,实现对入射毫米波的聚焦.给出了这种天线在94GHz处的实验验证,并得到了4dB的天线增益效果.     

费涅尔区板天线的设计及与馈源耦合问题的研究

将区板焦区场作为散射问题处理，得到区板感应面电流分布和焦区场分布后，本文利用场相关定理研究区板与馈源的耦合问题，并就主模激励下开口圆波导情形进行了计算和讨论。文中还采用矢量场绕射分析模型进行区板设计，给出了设计曲线     

基于菲涅耳波带板扫描的光学成像技术研究进展

基于菲涅耳波带板(FZP)扫描的光学成像是主动式非传统成像技术,通过二维光学扫描实现对目标的三维高分辨率成像.阐述了目前儿种不同类型的菲涅耳波带板扫描成像系统的原理、结构、性能,分析了国内外的研究现状和应用前景.     

光控菲涅耳波带片扫描天线

描述了基于光生等离子体效应的瞬态毫米波菲涅耳波带片扫描天线的工作原理.模拟计算了高阻硅片在不同激光光强照射下对毫米波的透射率,设计了毫米波在以不同偏离角入射时菲涅耳波带片的结构.分析了激光照射硅片形成不同焦距的波带片时天线的增益性质.实验验证了94 GHz波段天线,测试结果与模拟计算结果吻合得较好.     

A Novel Offset Fresnel Zone Plate Antenna

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偏馈FZPA焦区场特性研究

基于菲涅尔原理提出了一种椭圆形相位修正区域的偏馈菲涅尔区相位修正平面反射面天线（ＦＺＰＡ），在正入射和斜入射等不同情形下，利用物理光学法分析了其聚焦平面的场幅分布。有关结果表明，这种新型的ＦＺＰＡ具有良好聚焦特性，达到了设计目的。     

一种宽带双极化共享折合臂天线设计

针对L、S波段双极化信号宽带监测,提出了一种宽带双极化共享折合臂（dual-polarized shared-folded-dipole,DPSFD）天线. 天线采用宽度渐变振子臂和共享折合枝节结构,这种设计使天线的相对带宽由原来的57.8%拓宽到85.7%,并改善了天线高频段方向图分裂的问题. 理论和实验测试表明:天线在1.6~4 GHz频带范围内,电压驻波比小于2,典型增益为8.3 dBi,天线尺寸仅为最低工作频率对应波长的28%. 新设计的天线可应用于通信信号宽带双极化监测系统中.     

太赫兹开槽介质型菲涅尔天线设计

设计了一款工作在太赫兹频段的开槽介质型菲涅尔(Fresnel)透镜天线,该天线由馈电结构和透镜结构两部分组成。利用CST微波仿真软件,首先设计波纹喇叭馈电结构,其次基于波纹喇叭馈电结构设计开槽型菲涅尔透镜天线,分析全波周期、焦径比和子区等对天线性能的影响,通过横向和纵向对比,确定最佳天线参数。结果表明对天线性能影响从大到小分别为:焦径比、全波周期、子区。焦径比F/D=3、全波周期w=3、子区P=4为最佳天线参数,波纹喇叭馈电天线经过开槽介质型菲涅尔透镜天线聚焦后,天线的增益提升12.5 d B。     

Development and analysis of a folded shorted-patch antenna with reduced size

The length of a wall-shorted rectangular patch antenna can be reduced from /spl sim//spl lambda//sub 0//4 to /spl sim//spl lambda//sub 0//8 by a simple folding operation, which results in a stacked shorted-patch (S-P) structure with a resonant frequency that can be controlled by modifying the distance between the stacked (lower and upper) shorted-patches. A theoretical analysis based on a simple transmission-line model is presented and compared with numerical simulations, showing good agreement if the height of the folded patch is much smaller than the patch length. The physical insight of the variation of the resonant frequency for this reduced-size antenna can be understood by considering the antenna as a shorted patch loaded with a capacitor. An experimental verification is carried out for a 15 mm/spl times/15 mm/spl times/6 mm folded S-P antenna prototype designed for the 2.4 GHz ISM band that can achieve a 10-dB return loss bandwidth of 4% and results in a nearly omni-directional radiation pattern.     

一种Ka波段宽带折合式平面反射阵天线设计与实现

基于反射面天线技术提出了一种工作于Ka波段的宽带折合式平面反射阵天线(Folded Reflectarray Antenna,FRA)。该天线的主、副反射面均采用平面反射面的设计方案,基于双层贴片单元结构设计并实现了主反射面,并通过尺寸变换型单元来实现相位补偿、极化扭转以及大通带特性,副反射面采用双层极化栅来实现对单一极化波的透射。利用电磁仿真软件Ansys HFSS与CST MWS对天线结构进行分析设计,并加工出实物。仿真与实测结果表明,该天线3 dB增益带宽达到了20%,波束宽度在6°以内,在33～40 GHz的通带范围内,天线实测增益达到了26 dBi以上。     

A Systematic Study of Varying Reference Phase in the Design of Circular Fresnel Zone Plate Antennas

A circular Fresnel zone plate antenna was simulated using a finite difference time domain software to study the effect of changing the reference phase from the standard 0deg to any value between 0deg and 180deg. Several prototypes were built to validate the simulations using four different focal-length-to-diameter (F/D) ratios. It was found that a significant improvement in the level of the first sidelobe, up to about 9 dB according to the simulations, could be achieved without sacrificing gain or cross-polarization levels     

Analysis of square Fresnel Zone Plate Lens for dual band detectors

Dust emission is used in space applications for star-formation characterization normally acquired by different detectors operating at Infrared (IR) and sub-millimeter wave (sub-mm wave) frequencies. An integrated dual band detector working at both frequency ranges is described in this paper. The proposed configuration implements a spiral antenna working at sub-millimeter wave frequencies whose design is based on Fresnel zones theory. At the same time, this spiral antenna is used as Fresnel lens to focus IR power (12 μm) into an IR detector. The paper describes the influence of implementing a sub-mm wave spiral antenna based on square Fresnel zones. In particular, the effects on the focal distance and the focal gain at IR frequencies and the radiation features at sub-mm wave frequencies are studied. Furthermore, the importance of the number of Fresnel zones used in the design of the sub-mm spiral antenna is also determined.     

基于TFT-LCD的相位型菲涅尔波带片生成的中空光束

中空光束具有特殊的物理性质,在光信息处理、微电子学、同位素分离和分子光学等领域有着广泛的应用。本文提出采用TFT—LCD制作相位型菲涅尔波带片,平面波经TFTLCD衍射生成中空光束。实验结果表明,基于TFT—LCD的菲涅尔波带片生成的中空光束具有实时可调、快捷和精确等优点。     

Design of modified folded dipole antenna for UHF RFID tag

A simple tag antenna for the Korean ultra-high-frequency radio frequency identification (RFID) band (908-914-MHz) using a modified dipole structure is proposed. The overall dimension of the tag antenna is 64.1 times 17.8-mm. The input impedance of the designed tag antenna is 43-j800 Omegaand is conjugately matched to a Philips EPC UCODE Gen 2 RFID tag microchip with an impedance of 43-j800 Omega at 912 MHz. Good wake-up sensitivity and radiation pattern characteristics were obtained in the desired frequency band.     

一种折叠反射面天线的结构设计

针对机动雷达反射面天线结构尺寸运输超限问题,介绍了在结构设计过程中依据载荷分析计算结果,应用三维建模技术,虚拟装配技术,优化结构布局,完成自动展开/折叠反射面天线的结构设计。该天线在工作状态展开,在运输状态收缩到规定运输界限范围内,满足了雷达机动要求。     

Wideband and compact folded loop antenna

A simple and successful design method that yields a wideband and compact antenna without a ground plane is proposed. The antenna, referred to as the folded loop antenna, can, with the right parameters, achieve wideband characteristics. Calculated and measured results agree well and more than 50% bandwidth (return loss /spl les/-10 dB) is obtained.     

Design and measurement of beam reconfigurable antenna based on folded dipole structure

A reconfigurable antenna based on a folded dipole structure has been designed to operate at 2.45 GHz. The antenna consists of a folded dipole and a reflector. Depending on the states of the switches, the antenna symmetrically changes its shape and thus steers the beam pattern. The measured reflection coefficient and radiation pattern are presented. Also, the antenna is shown to have a larger gain with the reflector than without.     

A Full Electromagnetic Analysis of Grooved-Dielectric Fresnel Zone Plate Antennas for Microwave and Millimeter-Wave Applications

Grooved-dielectric, phase-correcting, Fresnel zone plate antennas are analyzed using the body-of-revolution finite-difference time-domain (BOR-FDTD) method. Parametric studies of the focusing ability of these antennas are performed to examine the effects of the focal length, diameter, number of zones, and the thickness of the lens, as well as the number of phase corrections per zone. The results of these studies are presented as design graphs and are used to lend insight into the focusing mechanism of phase-correcting zone plates. The BOR-FDTD analysis is validated by comparison with previous measurements.     

折合式平面反射阵天线的研究进展

折合式平面反射阵天线(folded reflectarray antenna,FRA)作为一种高增益天线形式,在雷达、通信等领域有着良好的应用前景.在继承平面反射阵天线易加工、低成本、平面化等特点的同时,FRA巧妙地利用了光路折合原理,具有更低剖面、无馈源口径遮挡等优点,自其概念提出以来便一直受到学术界和工业界的广泛关...     

A monopole antenna loaded with a modified folded dipole

A traveling-wave distribution of current can be produced on a linear antenna by inserting a resistance of suitable magnitude one-quarter wavelength from its end. In this study the resistor is replaced with a modified folded dipole which has a radiation resistance approximately equal to that of the matching resistor. Thus the input section has a traveling wave distribution up to the inserted antenna, as before, but now the power that was previously dissipated in the resistor is also radiated. Input impedance, current distribution, and radiation patterns of this antenna are computed, and input impedance and radiation patterns are also measured. Horizontally polarized patterns are similar to those of a horizontal dipole over a ground plane, and vertically polarized patterns in a plane orthogonal to the folded element are similar to those of a monopole over a ground plane. Coverage is also obtained in the zenith direction in the plane of the folded element, as long as it is not an integral number of half wavelengths above the ground plane. The peaks and nulls can be controlled by adjusting the monopole height accordingly and it is possible to achieve near hemispherical coverage