一种微带反射阵列天线单元特性研究

带开路短截线的贴片是微带反射阵列天线设计中最常用的单元形式之一。结合应用于民用航天领域的薄膜反射阵列天线设计,比较和分析不同物理参数、阵列环境下单元电讯性能变化特点,并优化设计单层薄膜反射阵列天线试验阵面,给出分析结果,供不同应用背景下的反射阵列天线设计参考。     

一种高增益低旁瓣双贴片微带天线阵

设计了一种可工作于Ku波段的高增益、低剖面的准空气微带阵列.天线阵列整体采用分层的准空气微带结构,每个天线单元采用双贴片单元结构以提高天线增益、抑制交叉极化,最终提高了组阵的效率和增益.在阵列天线中采用台阶式分块馈电,有效地抑制了旁瓣电平.最后通过仿真计算设计并实际制作了64单元阵列天线,实验结果和仿真结果吻合良好,阻抗带宽达到17.54%,中心频率14.25 GHz时增益达到24.5曲,E面旁瓣低于-18 dB,H面旁瓣低于-12 dB.     

采用EBG地的低剖面微带定向天线设计

对具有金属地的微带定向天线,低剖面设计面临着工作频带窄的难题。采用蘑菇形EBG结构代替微带定向天线的常规金属地,利用EBG地对特定频率电磁波的同相反射特性,在保持天线工作频带条件下,缩减天线微带基板的厚度,实现低剖面设计。以一只工作频点为5.8 GHz的2×2微带阵列天线为例,该阵列天线的辐射单元采用分形结构以进一步提升天线带宽。仿真计算和实际测试表明:该微带阵列天线在采用低剖面设计后,微带基板厚度由原1.0 mm降至0.25 mm,而天线的定向辐射方向图、增益和工作带宽基本保持不变。     

LTCC圆极化双层微带阵列天线的设计

利用低温共烧陶瓷(LTCC)工艺制作以陶瓷作为基板的双层圆极化微带阵列天线。传统设计中,使用柔性基板制作多层寄生微带阵列天线,由于加工精度及基板之间空气层的原因,阵列天线的圆极化特性以及阻抗匹配与仿真结果相差较大。该文采用低损耗高频陶瓷材料设计了应用于X波段的16单元双层圆极化微带阵列天线。通过实际测试,16单元阵列天线具有较好的带宽和圆极化特性,从而验证了LTCC技术可以很好地应用于微带阵列天线的研制。     

宽带低副瓣微带反射阵列天线

为了实现便携式雷达设备的轻小型化,系统采用微带反射阵列天线替代传统的抛物反射面天线.该天线设计的难点是如何实现雷达工作频带内的天线低副瓣特性.采用微带延迟线的移相方案,并提出微带贴片与延迟线满足线性相移关系的匹配原则,实现了反射阵列天线的宽带低副瓣特性.实测结果表明,在X频段3.2%的带宽内,天线副瓣电平低于-25 dB,并且天线效率不低于50%.     

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。     

一种宽带微带单脉冲阵列天线设计

设计了一种工作在C波段的宽带微带单脉冲阵列天线,采用口径耦合馈电和附加寄生贴片方式拓展微带天线带宽,利用三分支定向耦合器结构设计宽带微带和差网络,并与4×4微带阵列天线组成宽带单脉冲阵列天线,设计仿真后加工实物,经过实测,天线工作带宽1.2 GHz。     

64单元X波段LTCC高增益圆极化微带阵列天线

采用双层矩形贴片加一对切角和2个缝隙的结构设计圆极化单元,并将其应用于X波段64单元高增益圆极化微带阵列天线。传统设计中,多层寄生微带阵列天线使用柔性基板制作,引起加工精度的问题及基板间空气层的存在,使阵列天线的圆极化特性及阻抗匹配与仿真结果相差较大。该文采用低温共烧陶瓷(LTCC)材料设计了应用于X波段的64单元双层圆极化微带阵列天线。实验结果表明,64单元阵列天线增益达到22.03dBi,S11<-10dB的相对阻抗带宽达到6.36%,天线具有良好的圆极化和阻抗匹配特性。从而验证了在研制微带阵列天线方面LTCC技术可很好地得到应用。     

一种新型双频微带反射阵的设计

设计了一种新型双频微带反射阵.该反射阵采用上层为Ka波段阵面、下层为X波段阵面的双层结构,阵列单元由圆与圆环组合单层结构构成.在此基础上,分别选择圆环贴片型和方环缝隙型频率选择表面作为上下两层阵面的接地板,并与传统导体接地板反射阵作比较分析.仿真结果表明:采用频率选择表面作为接地板,不仅使反射阵天线获得较好的双频辐射特性,同时可有效地降低两个阵面之间的相互影响.     

新型Ku频段全向微带阵列天线

设计了一种新型Ku频段全向天线,该天线由双面辐射微带阵列组成,通过串联形式馈电,实现了全向中等增益辐射特性.文中给出了微带阵列天线的设计方法,对该微带阵列天线的阻抗带宽特性、方向图特性和馈电结构进行了分析.结果表明,该微带阵列天线反射损耗小于-10 dB的绝对带宽为1.15 GHz,在可用频带内全向增益为6.8 dB～7.3 dB,E 面波束宽度在20°～24°,H面方向图不圆度在±0.5 dB以内.该天线能够满足微波通信系统要求.     

The development of inflatable array antennas

Inflatable array antennas are being developed to significantly reduce the mass, the launch vehicle stowage volume, and the cost of future spacecraft systems. Three inflatable array antennas, previously developed for spacecraft applications, are a 3.3 m×1.0 m L-band synthetic-aperture radar (SAR) array, a 1.0 m-diameter X-band telecom reflectarray, and a 3 m-diameter Ka-band telecom reflectarray. All three antennas are similar in construction, and each consists of an inflatable tubular frame that supports and tensions a multi-layer thin-membrane RF radiating surface with printed microstrip patches, The L-band SAR array achieved a bandwidth of 80 MHz, an aperture efficiency of 74%, and a total mass of 15 kg. The X-band reflectarray achieved an aperture efficiency of 37%, good radiation patterns, and a total mass of 1.2 kg (excluding the inflation system). The 3 m Ka-band reflectarray achieved a surface flatness of 0.1 mm RMS, good radiation patterns, and a total mass of 12.8 kg (excluding the inflation system). These antennas demonstrated that inflatable arrays are feasible across the microwave and millimeter-wave spectrum. Further developments of these antennas are deemed necessary, in particular, in the area of qualifying the inflatable structures for space-environment usage     

Design and fabrication of a wideband reflectarray antenna in Ku and K bands

The purpose of this paper is design of a wide band single layer reflectarray antenna using a new broadband cell. The proposed cell consists of two parts. The first part is a circular patch and the second one is a ring with some additional stubs, which are attached to the patch and ring in a symmetrical form. The circular patch and ring elements are designed at frequencies of 20 GHz and 15 GHz respectively. In order to increase the reflectarray antenna bandwidth, at first the dimensions of the patch, ring and stubs are optimized to attain uniform phase response in the frequency range from 11 GHz to 20 GHz. Then an air layer is considered under the dielectric substrate. The reflectarray antenna is designed based on this optimized wideband unit cell. A wideband horn antenna is also designed as a feed antenna for the proposed reflectarray structure. The reflectarray antenna with horn are simulated. The 1 dB gain-bandwidth of 4.66 GHz is obtained (27.4% fractional bandwidth) in the frequency band of 14.72 GHz to19.38 GHz. Finally, the reflectarray antenna is fabricated and tested. It can be seen that there is a good agreement between simulation and measurement results.     

基于时域调制反射阵列的波束赋形技术

传统的反射阵利用相控器件与微带线实现波束赋形。为了降低相控成本与系统复杂度,提出基于时域调制阵列波束赋形技术。时域调制反射阵列是一种基于简单可重构反射单元的反射阵,它利用控制可重构反射单元的开与关,达到控制阵列输出,实现旁瓣抑制、波束赋形等功能。通过理论推导及仿真,结果表明,时域调制反射阵可以在不采用传统阵列中的相控器件及馈电网络的前提下,采用最小方差无失真响应波束赋形方法与时间调制法,生成理想的方向图,实现波束赋形功能。此特性将有利于推广波束赋形技术在毫米波频段反射阵的应用。     

Broadband reflectarray with combination of cross and rectangle loop elements

A reflectarray antenna composed of a combination of cross and rectangle loops of variable size printed on a conductor-backed substrate is presented. Using this type of cell element, a wideband, single-layer reflectarray is fabricated and measured. The bandwidth performance of this reflectarray is comparable to the previously reported best figures for reflectarrays using stacked-patch cell elements. Measured results demonstrate a radiation efficiency close to 60% and a 1 dB gain bandwidth of 24%, centred at Ku-band.     

Novel Broadband Reflectarray Antenna with Windmill-Shaped Elements for Millimeter-Wave Application

A novel broadband millimeter-wave reflectarray antenna composed of windmill-shaped elements of variable lengths is proposed. Compared to the conventional single-layer reflectarray elements, the windmill-shaped elements can realize much larger phase variation range (over 600°), leading to broader bandwidth. Using this technique, a 15°-beam-steering reflectarray operating at 30 GHz is designed. The computed results demonstrate the agreement of the main beam steering with the design requirement, and a 1-dB gain bandwidth close to 20% is obtained. The validity of the obtained results is verified by comparing the ones generated by Ansoft High Frequency Structure Simulator (HFSS) with those produced by Ansoft Designer. The antenna is useful for millimeter-wave applications.     

Bandwidth of reflectarrays

It is shown that the dominant factor controlling reflectarray bandwidth is the bandwidth of the radiating element, and that the effect of non-constant path delays over the surface of the flat reflector has little significance unless the aperture is electrically very large and the f/D ratio is small. An example of a polarisation-twist reflectarray using aperture coupled elements with time delay lines is used to demonstrate this conclusion.     

基于遗传算法的非对称多波束反射阵天线设计

针对传统方法设计的多波束反射阵天线增益低、波束偏移大、要求波束对称等问题,通过引入全局优化算法中的遗传算法对反射阵相位分布进行优化,以完成非对称多波束反射阵天线设计。为验证其有效性,设计并制作了一副Ku频段,波束指向分别为θ1=25°,1=0°和θ2=15°,2=180°的非对称双波束反射阵天线。测试和仿真结果较吻合,天线在中心频点的增益为26.03dBi,效率达到28.04%,1dB增益带宽和3dB轴比带宽均能覆盖11.3~12.3GHz(8.3%),实测波束指向为θ1=24.3°,1=0°和θ2=15°,2=180°,波束偏移0.7°。结果表明遗传算法能有效完成非对称多波束反射阵天线设计。     

A C/ka dual frequency dual Layer circularly polarized reflectarray antenna with microstrip ring elements

This paper reports a dual frequency dual layer circularly polarized reflectarray operating in the C and Ka bands. A 0.5-m right-hand circularly polarized planar reflectarray antenna is designed using microstrip ring elements of variable rotations to achieve a cophasal beam at broadside. The microstrip ring elements are more compact than the traditional reflectarray elements and can minimize blockage for the multilayer multifrequency applications. The highest efficiencies measured are 46% at 7.3 GHz and 38% at 31.75 GHz. The tested cross-polarization levels are -21 dB at 7.3 GHz and -29.2 dB at 31.75 GHz at the broadside direction. The tested results show that the designed ring element is suitable for both the single and dual layer applications with good bandwidth and circularly polarized performance.     

Design of millimeter wave microstrip reflectarrays

This paper discusses the theoretical modeling and practical design of millimeter wave reflectarrays using microstrip patch elements of variable size. A full-wave treatment of plane wave reflection from a uniform infinite array of microstrip patches is described and used to generate the required patch-design data and to calculate the radiation patterns of the reflectarray. The critical parameters of millimeter wave reflectarray design, such as aperture efficiency, phase errors, losses, and bandwidth are also discussed. Several reflectarray feeding techniques are described, and measurements from four reflectarray design examples at 28 and 77 GHz are presented     

Investigations into a power-combining structure using areflectarray of dual-feed aperture-coupled microstrip patchantennas

This paper details an investigation of a power combiner that uses a reflectarray of dual-feed aperture-coupled microstrip patch antennas and a corporate-fed dual-polarized array as a signal distributing/combining device. In this configuration, elements of the reflectarray receive a linearly polarized wave and retransmit it with an orthogonal polarization using variable-length sections of microstrip lines connecting receive and transmit ports. By applying appropriate lengths of these delay lines, the array focuses the transmitted wave onto the feed array. The operation of the combiner is investigated for a small-size circular reflectarray for the cases of -3 dB, -6 dB and -10 dB edge illumination by the 2×2-element dual-polarized array