基于人工磁导体的低RCS微带天线设计

基于人工磁导体(AMC)的工作机理,设计了一款工作频率在X波段的低雷达散射截面(RCS)微带天线。设计了一种AMC单元,经X和Y极化波垂直入射在8.6~14.6 GHz的频带范围内,获得180°±37°的反射相位差;将其进行正交排列组成AMC棋盘结构的反射屏,反射屏中AMC阵列块由3×3的单元组成。仿真结果显示,该反射屏较相同尺寸的PEC板具有更小的后向RCS,将此AMC结构与工作频点为10 GHz的微带天线共面排布,在保持原有天线良好辐射性能和剖面高度的同时,在8.4~14.8 GHz的频率范围内对两种极化波垂直入射实现了不低于7.5 dB的RCS缩减量。     

带宽极限下的宽带平面反射阵天线设计

平面反射阵是由金属贴片单元组成的二维阵列,一般用喇叭馈源进行馈电,通过谐振贴片单元的相移量补偿馈源到平面反射阵的空间相位延迟。平面反射阵天线的优势在于主波束指向灵活可控。但由于阵列单元自身的带宽限制和反射机理所致,其主要缺陷是工作带宽窄。在讨论空间相移对天线性能的影响的基础上,设计了一种相位线性变化达500°的新型反射阵单元。用该单元组阵的平面反射阵天线,其1 d B带宽达到25.3%,与传统平面阵结构的天线带宽相比,具有显著的改善。     

一款双频双宽带双圆极化Fabry-Perot谐振腔天线

文中设计了一款双频双宽带双圆极化的法布里-珀罗（FP）谐振腔天线。传统的FP天线具有高增益特性但是难以实现宽带及双频带工作，为了改善其性能，提出一种具有双频正相位梯度的部分反射表面，利用其正相位梯度特性弥补电磁波频率升高带来的空间相位变化，从而在较宽的带宽内满足FP天线的谐振条件以实现宽带辐射。通过加载寄生贴片以及缝隙耦合馈电的方式设计宽带圆极化馈源，并且采用人工磁导体结构替代传统的金属地板，在同一谐振腔高度下满足两个频段的谐振条件，简化了双频FP天线的结构。全波仿真结果表明，所提出的FP天线3 dB轴比带宽分别为10.1%和13.8%，峰值增益达到12.45 dBi和11.9 dBi,3 dB增益带宽分别为11.5%和14.8%。     

基于超表面的低雷达散射截面宽频贴片阵列天线设计

该文设计了一种基于超表面(MS)的低雷达散射截面(RCS)宽频贴片阵列天线。该天线由工作在不同频段的两种开缝贴片天线组成2×4的八元阵,以此实现天线小型化并扩展其带宽,根据相位相消原理,将两种人工磁导体(AMC)以棋盘布阵的方式组成超表面加载到天线阵周围,使其具有低RCS特性。实测和仿真结果表明:加载超表面后,天线工作带宽由5.7~6.2 GHz扩展为5.6~6.6 GHz,相对带宽增大1倍,辐射特性基本保持不变;当平面波垂直入射时,天线单站RCS减缩效果明显,其中,X极化波下3 dB减缩带宽为5.3~7.0 GHz,最大减缩量达31 dB,Y极化波下3 dB减缩带宽为5.8~6.9 GHz。     

5G中的超宽带阵列天线及其小型化技术

研究了超宽带阵列天线的设计及其低剖面技术。将ADS电路仿真软件与电磁场全波仿真软件Ansoft HFSS相结合,利用具有紧耦合的偶极子天线单元设计具有宽带工作的低剖面强耦合阵列天线。研究结果表明,在工作频率范围0.67~3. 78 GHz频段内,该天线阵列的电压驻波比优于2. 0,相对带宽为139. 78%,天线阵列的剖面仅有40.25 mm。其次,研究了加载人工磁导体结构实现阵列天线的低剖面技术。采用构成高阻抗地的人工磁导体结构改善了天线高频谐振性能,从而降低了天线的剖面高度。全波电磁仿真结果表明,该天线阵列在1. 1 ~ 2. 8 GHz范围的工作频率中电压驻波比优于2. 0,天线的剖面高度仅为24 mm,相对带宽78%。该技术可拓展应用到5G天线的开发。     

一种微带反射阵列天线单元带宽拓展方法

在微带反射阵列天线设计中,采用大小不同、结构相似的多个空心单元于同一层面上嵌套形成组合单元,可以拓展单元带宽.通过几种单元实例计算对比和实验阵面性能的仿真分析,结果表明采用此组合单元可有效拓展阵中单元及微带反射阵列天线系统的工作带宽.应用此组合单元法步骤简单,具有一定的通用性,可为各种反射阵列天线设计和工程实践参考.     

一种具有增益改善的低散射缝隙天线设计

基于次辐射源和相位对消原理,研制了一种新型可用于雷达低可见平台的波导缝隙天线。利用人工磁导体和理想电导体组成的棋盘型复合表面代替全金属表面,实现改善天线增益的同时减少雷达散射截面积(RCS)的目的。实测结果表明:加载棋盘型复合表面的缝隙天线E面和H面方向图增益提高5dB以上,同时天线工作频带内RCS减少8dB以上。     

一种新型单层宽带微带反射阵天线设计

针对微带反射阵天线带宽窄的问题,提出了一种新型线极化双谐振宽带"蝴蝶"形单元结构,详细描述了单元结构设计步骤,研究了不同基板以及不同结构参数对单元相位曲线的相移范围、平滑度以及谐振点位置的影响。仿真测试表明,该单元结构能够在5.5-7GHz带宽内具有良好的相位特性曲线。对36个"蝴蝶"形单元组件测试表明,其在20%带宽内辐射效率达到40%以上,最大辐射方向上交叉极化电平小于-30dB。此外,"蝴蝶"形单元结构类似于"十"字形单元结构,有利于进一步扩展实现多频带、多波束反射阵天线设计。     

多波束涡旋电磁波反射阵天线设计

针对传统反射阵天线产生涡旋电磁波存在方向单一、轨道角动量(Orbital Angular Momentum, OAM)模态单一的问题,设计了一款多波束涡旋电磁波反射阵天线。提出了一款基于旋转单元法的新型宽带圆极化单元,并利用口径场叠加法,获得了单个馈源产生多个涡旋波束的反射阵阵面补偿相位。仿真结果表明,该天线在26.5～32 GHz生成了2个携带模态-1和+1的涡旋波束,OAM带宽和3 dB增益带宽均为18.3%。在工作带宽内,最大增益为18.3 dBic,口径利用效率为10.31%。     

K波段高增益宽带的异极化透/反射阵列天线

提出了一种具有新型多功能空间馈电平面的阵列天线,可以同时实现透/反射两个波束。该阵列通过快速响应编码对圆环反射单元和透射单元进行合理分布,以实现不同极化方向的透/反射波束。基于所提出的透射和反射单元,设计并制造了具有25×25个单元的透射-反射阵列天线,分别产生θ=0°向后的x极化方向的反射波束和θ=180°向前的y极化方向的透射波束。该天线的中心频率为22 GHz,测试结果表明,反射波束最大增益为22 dB,3 dB增益带宽达到28%;透射波束的最大增益为19.2 dB,3 dB增益带宽达到27%。     

Wide band radar cross section reduction by thin AMC structure

A new thin and wideband RCS reduction metasurface is designed and fabricated by using two different AMC unit cell tiles arranged in chessboard like configuration. One of these tiles is formed by saltire arrow unit cells, whereas the other one is formed by Jerusalem unit cells which are designed to achieve out phase difference at broad frequency range. This metasurface reduces the RCS more than 10-dB from 15.75 GHz to 41.3 GHz (90% bandwidth). The designed metasurface works properly at both TE and TM propagation modes, also. Moreover, it has stable 10-dB RCS reduction bandwidth for TM propagation mode up to 50° oblique incident angle and 30° for TE ones. These good specifications prove the designed metasurface capability compared with the state of the art references.     

宽带低RCS超表面天线阵设计

该文利用电磁超表面与微带天线的结构高度相似性,设计了2种辐射特性几乎一致且具有反射相位差异的超表面天线,通过将2种天线单元进行棋盘布阵,在x极化波和y极化波照射下分别利用相位相消及匹配负载吸收实现了天线阵带内散射能量的抑制。实测与仿真结果表明:该超表面天线工作于6.0～8.5 GHz。x极化波垂直入射时天线单站RCS减缩6 dB带宽为6.2～10.5 GHz,最大减缩量达21.07 dB。y极化波垂直入射时天线的带内RCS减缩依然能达到3 dB以上。且实测与仿真结果吻合良好。该设计方法为实现天线阵带内RCS减缩提供了新的设计思路。     

Radiation performance improvement of wideband microstrip antenna array using wideband AMC structure

In this paper, the radiation performance of an antenna array is improved by designing a new wideband artificial magnetic conductor (AMC). The proposed AMC surface operates at the frequency of 3 GHz with ±90^° reflection phase bandwidth of 22%. In order to identify the key design parameters of the AMC structure, a parametric study is performed. To improve the radiation performance of the antenna array, an AMC reflector is developed through utilizing an array of 2 × 8 periodic patches of AMC unit cells. By this technique, the front to back ratio of the designed antenna array is enhanced about 16.27 dB. It is concluded that tuning of the AMC dimensions for controlling the reflection coefficient at each port of antenna array during beam steering is necessary. Because of the using of the AMC surfaces as a reflector instead of conventional PEC surfaces, size reduction of the antenna array in the order of 20% is achieved. In this study, a circuit model for single element of the antenna array with considering AMC loading effect is introduced, which predicts the bandwidth behaviour of the proposed antenna. The final designed antenna array exhibits low level of cross polarization making it well‐suited for tracking radars and electronic warfare applications. The proposed antenna with the AMC reflector is fabricated and measured. The measured ?10 dB impedance bandwidth and peak gain of the proposed antenna is 20% (2.7‐3.25 GHz) and 13.4 dBi, respectively, which are compatible with the simulation results.     

具有超宽带RCS减缩特性的天线设计

该文设计了两种人工磁导体(AMC)单元,在8～20 GHz的超宽频带内,两种AMC结构能够实现180°±37° 的反射相位差,将这两种单元组成棋盘结构时,能够实现入射电磁波的散射场相消,从而在超宽的频带内实现棋盘表面法向雷达散射截面(RCS)的显著减缩。同时,利用超表面天线的概念,设计馈电网络,将设计的AMC结构用做天线,仿真发现在9.08～10.30 GHz的范围内,天线的S₁₁小于–10 dB,可以实现天线的有效辐射。实测结果和仿真吻合较好,因此该文的棋盘结构可以实现具有RCS减缩特性的天线设计。     

一种45°极化的毫米波二维宽带宽角扫描相控阵

设计了一款工作于Ka波段的+45°极化宽带宽角扫描相控阵.基于电磁镜像原理,通过嵌入人工磁导体,提出了一款具备宽波束辐射能力的+45°极化天线单元,其相对带宽达18.2％,水平方位面的3 dB波束宽度达114°,展示出宽角扫描潜能.将上述单元组成4×16均匀面阵并研究相控阵宽角扫描特性.计算结果表明,该面阵能在水平方位...     

Novel Design of a High-gain and Wideband Fabry-Pérot Cavity Antenna Using a Tapered AMC Substrate

A high-gain and wideband electromagnetic bandgap (EBG) resonator antenna with a tapered artificial magnetic conductor (AMC) ground plane is presented. The proposed EBG resonator antenna is comprised of a frequency selective surface (FSS) superstrate with a strip dipole array and an AMC ground plane with tapered rectangular patches. The realized gain and the bandwidth of the antenna can be improved simultaneously by using the tapered AMC where the phase difference of the reflected waves from the patches with different length is within 180° and the destructive interference among them can be considerably reduced. The maximum gain is increased about 2∼3 dB and the bandwidth is improved about 2.5 times compared to when the uniform AMC is used.     

分布式有源对消及测角误差影响分析

为减小测角误差对有源对消效果的影响,进而降低有源对消对测角系统性能的要求,促进有源对消技术在雷达散射截面(Radar Cross Section, RCS)缩减中的应用,基于平台及单个强散射源RCS 曲线随角度变化的特点,提出了分布式的有源对消方案。推导了包含测角误差的有源辐射场表达式,分析了测角误差对有源对消效果的影响方式,为减小测角误差的影响提供了指导。采用蒙特卡罗方法仿真分析了集中式有源对消和分布式有源对消的性能随测角精度的变化。最后在一定测角精度情况下,分析了不同幅度相位误差对分布式对消的影响。结果表明,分布式对消方案具有较为稳定的对消效果,在测角误差3°的情况下,为达到6dB 的缩减,相位和幅度容差分别达到10°和2 dB。上述结果为有源对消在RCS 缩减的应用中提供了新思路。     

A frequency-controlled beam-steering array with mixing frequency compensation for multichannel applications

A frequency-controlled beam-steering planar array with mixing frequency compensation is presented for cost-effective multichannel phased array applications. The new feed networks for frequency compensation not only operate in wide band but also ensure radio-frequency (RF) amplitude imbalance cancellation and progressive phase distribution. The parallel equal power dividers installed in both LO and intermediate-frequency (IF) feed networks provide uniform amplitude and phase distribution, while the fixed delay lines installed in the LO feed network exhibit precise phase progression, compared to a series feed structure. The LO power imbalance caused by the unequal delay line loss between elements is corrected by pumping each mixer into the LO saturation region, leading to linear IF-RF response. Thus, sidelobe degradation and pattern distortion caused by the RF amplitude imbalance, as well as the beam-steering error and beam squint caused by the phase errors of the delay lines, are removed. The proposed feed networks combined with quasi-Yagi antenna arrays and microwave monolithic integrated circuit mixers realize a broad bandwidth of more than 3 GHz in K band for multichannel wireless applications. The K band transmitter/receiver pair proposed in this paper successfully demonstrates two-channel simultaneous RF transmission and single channel 50-Mb/s data communication with 40/spl deg/ scanning. This simple, compact, yet cost-effective planar array ensures multichannel broadband wireless communications with beam-steering capability.