An experimental radome panel evaluation

Modern antenna radomes are made of materials that tend to shed water to minimize their RF attenuation when wet. The microwave performance of these materials has been studied experimentally. Radome attenuation was measured as a function of frequency, rain rate, rain incidence angle, RF incidence angle, and polarization. The tests were performed on (1) new, clean radome panels, (2) used, dirty radome panels, (3) cleaned, used radome panels, and (4) panels treated with hydrophobic paint. The results show weak loss dependence on frequency over the 13-20 GHz frequency range of interest, which increases slowly with rain rate from 2.5 to 29 mm/h except for surfaces that are wettable, where the dependence on rate is much stronger. Loss is nearly independent of rain incidence angle, but it is strongly a function of surface condition. Hydrophobic paint is shown to be very effective. The test setup used, limitations imposed by the real world, and a simplified model of radome loss derived from the test results are described     

C波段机载干扰机天线罩的分析与设计

运用微波等效网络法对机载干扰机天线罩进行了计算机辅助设计,计算的天线罩透波率、加罩天线辐射特性与实测结果相吻合。研制的C波段机载干扰机天线罩经高低温、振动、静压试验,性能良好,其透波率达85％以上,达到了设计指标要求。     

一种基于超材料的谐波抑制天线罩

设计了一种基于超材料结构的前置谐波抑制单元天线罩,该天线罩采用多层互补型亚波长单元结构,在一个天线单元的有限尺寸范围内排列更多的周期单元,减小边缘效应的影响,天线罩总厚度小于5 mm,通过PMI泡沫与喇叭天线连接。采用激光刻蚀工艺制备了不同尺寸的两种试验件,并进行了超材料的传输系数测试以及带罩天线阵谐波抑制性能测试,结果表明,所设计的超材料谐波抑制天线罩具有带内0.3 dB 的插损,二次谐波20 dB和三次谐波30 dB的抑制能力。     

纽扣式雷电分流条对雷达天线罩的传输影响分析

传统的金属雷电分流条难以满足高频雷达天线罩的电磁波传输要求,而纽扣式分流条可以兼顾防雷和电磁波传输。通过仿真和试验对比分析雷电分流条的电磁波传输特性,使分流条电磁波传输性能研究模型化。分析纽扣式分流条的电磁波传输机理,同时研究金属片形状、金属片间距和天线频率对雷达罩电磁波传输性能的影响。结果表明:金属分流条对雷达罩的电磁波传输性能影响严重,合理设计的纽扣式分流条可以有效传输电磁波;纽扣式分流条的金属片形状对电磁波传输影响明显,金属片横向越宽,对电磁波传输影响越大,圆形结构电磁波传输性能最差,窄菱形结构电磁波传输性能最好;纽扣式分流条的金属片间距对雷达罩的电磁波传输影响不大,主要影响其击穿电压;同一形式的纽扣式分流条,天线频率越高,电磁波传输性越差。     

试验天线对雷达罩传输效率的影响及分析

在雷达罩电性能测试过程中,需要用到试验天线,试验天线的类型、极化方式和口径尺寸对雷达罩电性能测试结果有一定影响。文中对试验天线口径尺寸对雷达罩传输效率的影响程度进行了仿真计算,通过对比测试验证了仿真计算的正确性。计算和测试结果表明:当试验天线与装机天线口径尺寸差别不大时,试验天线口径尺寸对传输效率的影响较小。在工程实践中,当无法得到装机天线时,可以用类型相同、极化方式相同、口径相近的天线作为试验天线,以完成传输效率的测试。     

Boresight errors induced by missile radomes

Radome induced boresight errors are defined in terms of antenna difference port to sum port voltage ratios. The antenna port voltages are derived using the reaction integral for the case of a planar waveguide slot array in the presence of a dielectric radome. Radome transmission uses planar slab results. Both the antenna reflection and the radome shadow contribution are taken into account. Although only linear copolarized comparisons are presented here, the analysis is kept arbitrary with respect to incident and seeker antenna polarizations. Measurements include a line source experiment that tests the antenna model sensitivity to geometry. A simple distributed source experiment, in the form of a planar slab radome with thickness corrugation, tests the influence of transmission through varying wall thickness. Effects of curvature are assessed with an offset hemisphere radome and finally a series of tangent ogive radome comparisons verify the limits of the analysis. A trend for the yaw errors to be less accurate than the pitch errors is consistently noted for the tangent ogive radomes, and this behavior is discussed.     

发射天线罩抗微波烧毁理论分析

本文给出了机载宽带大功率发射天线抗烧毁理论分析方法和实验结果 ,从天线近场理论出发 ,计算了天线罩、极化器、密封膜片等处的功率密度。结合材料特性 ,给出了天线罩等的安全距离的计算公式 ,并提出了具体的抗微波烧毁措施。     

一种小型化体外挽袖微带圆贴片微波热疗天线北大核心CSCD

小体积生物组织进行微波热疗过程中,热疗天线辐射的微波能量聚焦体积过大、治疗范围超出热疗目标区域烧伤其余健康组织,针对这一问题,文中提出了一种小型化体外挽袖式微带热疗天线。它由SMA连接器法兰盘两侧焊接的挽袖圆铜壳及两个圆形微带贴片组成。微带贴片的介质基底是相对介电常数为4.4的FR-4材料,基底厚1.6 mm。实测天线在915 MHz的反射系数为-18.5 dB,试验中由该天线加热40 mm×40 mm×40 mm的小体积猪肉组织,并采取红外热成像仪和热电偶两种测温方式测试天线加热情况,研究结果表明该天线有效治疗区域为20 mm×20 mm×10 mm的半椭球型,温度分布较为均匀,适用于小体积体外微波热疗系统。     

Corrections for the effects of a radome on antenna surfacemeasurements made by microwave holography

Measurements of the surface deviations of a parabolic antenna by microwave holography have been corrected for the effects of an enclosing radome. The largest correction, which is due to diffraction from the metal space frame, is made by using a model computed from the radome structure. This model accounts for the changing diffraction as the antenna is scanned during the interferometric mapping of the complex beam pattern. Correction for reflections from the radome panels is made by simultaneously measuring the beam pattern at multiple frequencies to provide delay discrimination to reject antenna sidelobes generated by multiple reflections which arrive with delays different from that of the main beam     

Numerical optimization of a cylindrical reflector-in-radome antennasystem

Accurate numerical optimization based on rigorous solution of the integral equation using the method of analytical regularization is performed for a cylindrical reflector antenna in a dielectric radome. It is shown that the multiple scattering in this system is more significant for the optimum radome design than any nonplane-wave effects or the curvature of the radome. We claim that, although the common half-wavelength design is a good approximation to avoid negative effects of the radome (such as the loss of the antenna directivity), one can, by carefully playing with the radome thickness, its radius, reflector location, and the position of the feed, improve the reflector-in-radome antenna performance (e.g., increase the directivity) with respect to the same reflector in free-space     

面向高铁卫星通信系统的高性能天线罩设计

设计了一款适用于高铁平台卫星通信相控阵天线的高性能天线罩.该天线罩针对载体应用环境，设计了双向对称、低剖面的气动外形，以满足载体高速双向对开时低空气阻力的要求；同时根据卫星通信相控阵天线波束扫描的特点，设计了变厚度夹层结构，以实现天线罩对任意极化方向的电磁波宽角入射时高透波率的电性能.以Ku频段为例，根据设计结果进行了实物制作和测试验证，测试结果显示在10.5~13 GHz频率范围内，采用垂直极化波和水平极化波分别照射时，天线罩在0~70°的入射角范围内，透波率均保持在80%以上，同时天线罩对相控阵扫描波束的指向误差维持在±0.5°范围内.     

一种基于介质填充的天线罩电厚度反射测试波导探头

电厚度是雷达天线罩重要的电性能参数,在天线罩制造过程中经常需要采用反射测量方法实现工艺控制,但测试能力严重受限于测试探头与被测天线罩的失配反射影响.在分析失配原理的基础上,提出了反射测试波导探头内部介质填充方法,通过结构不连续性和介质不连续性的分离,实现了失配反射信号的内部自然抵消.给出了明确的介质填充形状和结构参数设...     

搜零法在相控阵雷达罩电性能测试中的应用

在机载相控阵雷达罩电性能测试过程中,由于被测天线是相控阵天线,使得测试方法与经典测试方法有所不同.文中对搜零法在相控阵雷达罩电性能测试中的应用进行了探索,确定了搜零系统中相控阵天线的安装方式和收发电轴对准的判据,集成了一套相控阵雷达罩电性能搜零系统,系统功能和精度满足测试需求.还在X波段相控阵雷达罩电性能测试中验证了搜零法的有效性,测试数据规律正确且重复性良好.测试结果表明相控阵雷达罩电性能搜零系统可用于新型战斗机雷达罩研制过程.     

Optimization of two-dimensional radome boresight error performanceusing simulated annealing technique

A systematic approach to radome design is presented. The problem is formulated as a global optimization procedure such that the radome performance is optimized by properly adjusting the thickness of the radome layer over the entire radome surface. In this approach the thickness profile is parameterized via B-splines representation. Simulated annealing technique is applied to finding the best thickness profile so that the maximum boresight error is reduced to as small as possible over the entire range of the antenna look angle. A two-dimensional design example is given. The best possible thickness profile is found and the boresight error is reduced considerably compared to that due to a uniform layer. The method is general and can be applied without difficulty to other realistic three-dimensional radomes of arbitrary shapes     

天线罩对抛物面单脉冲天线极化特性的影响机理和仿真分析

单脉冲定向技术是目前最准确的电子定向技术之一, 被广泛应用于微波毫米波跟踪、监视、通信、测量、天文观测等系统.为了保护雷达天线免受环境的影响, 许多单脉冲天线都采用天线罩, 这会对单脉冲天线方向图的极化结构产生影响, 另外, 有意的电子欺骗干扰如交叉极化干扰会对定向性能产生较大影响.文章以雷达导引头普遍采用的X波段抛物反射面幅度比较单脉冲天线为对象, 分析了抛物面结构、初级馈源特性、天线罩引起交叉极化分量的机理, 建立了典型物理参数下的计算模型, 在Ludwig第三定义下对加入天线罩前后单脉冲天线交叉极化特性进行仿真, 综合考虑了天线几何形状、偏置结构、天线扫描等因素对极化特性的影响.结果表明:多种因素会引起单脉冲天线显著的去极化效应, 复杂的方向图极化结构使得单脉冲雷达导引头的定向精度敏感于电波极化方式, 这为进一步开展交叉极化对抗单脉冲跟踪技术研究提供了重要理论基础.     

电子定标法测试天线罩瞄准误差原理之分析

论述了电子定标法测试天线罩瞄准误差的原理方法,并分析了该方法成立的理由。电子定标法的步骤依次为:收发天线机械轴对准－天线和差通道自检－收发天线电轴对准－电子定标寅无罩测试寅带罩测试－查表计算天线罩瞄准误差。电子定标原理和实测结果表明:测试过程中接收天线差电压与和电压之商,可分解为相对自检过程的共模分量和正交分量;定标过程共模分量保持不变,它决定天线的零深;正交分量随收发天线夹角变化,不受天线零深影响,其曲线为定标曲线;无罩和带罩定标曲线线性度极好,其斜率为天线差斜率;天线加装高性能天线罩后,差斜率变化微小;故可以使用无罩天线差斜率和带罩测试的和差通道电压,计算得出天线罩瞄准误差。差斜率近似引入的误差很小,电子定标法成立。     

GaAs heterojunction bipolar transistor device and IC technology forhigh-performance analog and microwave applications

GaAs-AlGaAs n-p-n heterojunction bipolar transistor (GaAs HBT) technology and its application to analog and microwave functions for high-performance military and commercial systems are discussed. In many applications the GaAs HBT offers key advantages over the alternative advanced silicon bipolar and III-V compound field-effect-transistor (FET) approaches. TRW's GaAs HBT device and IC fabrication process, basic HBT DC and RF performance, examples of applications, and technology qualification work are presented and serve as a basis for addressing general capability issues. A related 3-μm emitter-up, self-aligned HBT IC process provides excellent DC and RF performance, with simultaneous gain-bandwidth product, f_T, and maximum frequency of oscillation, f_max, of approximately 20-40 GHz and DC current gain β≈50-100 at useful collector current densities ≈3-10 kA/cm², early voltage ≈500-1000 V, and MSI-LSI integration levels. These capabilities facilitate versatile DC-20-GHz analog/microwave as well as 3-6 Gb/s digital applications, 2-3 G sample/s A/D conversion, and single-chip multifunctions with producibility     

雷达天线罩电性能补偿技术

对于A型玻璃钢蜂窝夹层罩对雷达天线电性能的影响及接缝的电性能补偿技术进行了理论分析和实验,并对天线整罩进行了测试,提供了测试结果。     

一种基于电磁超材料的大规模天线阵列天线罩解耦技术

文中设计了一种去耦天线罩,为解决紧凑排列的大规模天线阵列中相邻端口隔离度较低的问题提供了参考.天线罩主体是一层具有低介电常数和低损耗性的介质板,其上印刷了周期性排列的金属贴片结构.通过调整金属贴片的形状以及天线罩到天线阵列的距离,使天线罩产生的反射波与阵中的耦合波幅度相同、相位相反,二者相互抵消,达到增加阵中端口间隔离...     

Microwave noncontact examination of disbond and thickness variationin stratified composite media

Numerical and experimental results of a microwave noncontact, nondestructive detection and evaluation of disbonds and thickness variations in stratified composite media are presented. The aperture admittance characteristics of a flange mounted rectangular waveguide radiating into a layered, generally lossy dielectric media backed or unbacked by a conducting sheet is modeled. The theoretical implementation is based on a Fourier transform boundary matching technique to construct the field components in each medium, coupled with a stationary form of the terminating aperture admittance of the waveguide. The model can serve as a reliable test bed for real-time examination of layered composite media. Experimental results for several cases are presented which show good agreement with the theoretical findings. This is a versatile technique for near-field in situ interrogation of stratified composite media which provides for high resolution measurements