新型电控可重构天线阵全向单元设计

该文提出了一种性能良好的新型方向图可重构天线阵全向印刷单元天线。该天线由两对半波振子背靠背印刷在介质板上构成,结构简单紧凑。相对带宽达50%(VSWR<2),在工作频带内,增益6.44 dBi,不圆度小于2.0 dB。文中给出了仿真设计结果和实测的电参数数据,两者有较好地一致性。本天线适用于WiMax(802.16)终端及WLAN基站或中继站天线。     

一种新型低剖面、双频、双极化宽频带阵列天线的研究与设计

设计了一种结构新颖的双频、双极化基站阵列天线并进行了仿真和实验研究。双频阵列由采用新型印刷金属圆弧耦合馈电的圆环天线(低频)与交叉微带印刷振子(高频)嵌套构成。首次采用印刷金属圆弧耦合馈电拓宽了圆环天线带宽,并利用反相馈电技术提高了端口隔离度(<-28dB)、加强了方位面方向图的对称性、降低了交叉极化电平;对在双频结构中受影响较大的高频阵元进行了相位误差分析;最后给出了整个双频阵列的实测结果,与仿真理论值吻合较好。该阵列天线具有宽频带(806~960MHz、1710~2170MHz)、低剖面(35mm)、高极化隔离、结构紧凑、方位面波瓣恒定(65±6°)等优点,适合用于双频基站系统或星载/舰载通信系统。     

微带线馈电的宽带单层贴片天线

微带贴片天线已广泛应用于雷达系统,文中介绍了一种新型背腔式单层微带贴片天线,辐射贴片采用微带线馈电,为增加工作带宽,提供了两种不同的贴片形状,第一种是E形贴片,仿真及测试结果表明,此种单元在驻波比优于2的条件下可实现45%的阻抗带宽,但该单元的波瓣带宽较窄。为抑制交叉极化,通过在E形贴片上开四个槽,得到了第二种改进的E形贴片。该单元可实现14%的频带内驻波比优于1.5,同时交叉极化优于-15dB。对C波段8×16单元实验小阵的测试结果表明,该天线在17.9%的频段内具有良好的交叉极化性能及较高的工作效率。     

Fixed-Beam Frequency-Tunable Phase-Reversal Coplanar Stripline Antenna Array

A fixed-beam frequency-tunable coplanar stripline (CPS) antenna array using the phase reversal technique and varactor diodes tuning is presented. The antenna array is composed of plurality of half-wavelength CPS sections interconnected by phase reversing crossovers. These crossovers have two functions: they serve as the radiators (small dipoles) of the array and also provide their own required in-phase excitations for broadside radiation. Two microstrip-to-CPS transitions for excitation of the balanced input/output antenna array are implemented and compared. A six-element array is demonstrated theoretically and experimentally, with 9.3 dBi of gain for bidirectional radiation and 12.5 dBi of gain for unidirectional radiation using a back reflector. Moreover, shunt varactor diodes are incorporated along the CPS structure to achieve frequency tuning through a bias voltage control while broadside radiation patterns remain fixed. The return loss and the radiation patterns at several frequencies are presented, and up to 50% tuning range is obtained. The proposed antenna array is simple and uniplanar with small lateral size, high radiation efficiency and high directivity. In addition, it uses a very simple biasing circuit with high DC-RF isolation. Its balanced input/output makes it suitable for RF system integration and active integrated antenna design.     

A Double Rhombus Antenna Fed by 180$^{circ}$ Phase Shifter for Ultrawideband Phased Array Applications

A double rhombus antenna fed through a microstrip 180deg phase shifter is presented. The 180deg phase shifter is a novel design of microstrip-to-coplanar waveguide (CPW)-to-microstrip transition. The proposed phase shifter is obtained without changing the layer of the second microstrip line for an easy embedding into the feedline. Via holes are used to transfer the current from the top to the bottom substrate layer and vice versa. The antenna with the phase shifter is operating in a wide bandwidth from 5.7 and 18.6 GHz (106%), and provides stable endfire radiation patterns. This design is tested in a modified two-element array configuration and proved to have a wide usable bandwidth.     

Broadband Patch Antenna With a Folded Plate Pair as a Differential Feeding Scheme

A broadband differential-fed patch antenna (DFPA) with good radiation pattern is proposed and studied. Unlike conventional DFPAs, the proposed antenna employs a folded plate pair as the differential feeding scheme. The devised feeding approach subtly acts as an impedance matching media for two radiation modes of the antenna, conducing to the wide impedance bandwidth. The conceived bandwidth enhancement technique demonstrates an impedance bandwidth (SWR les2) of up to 74% which outperforms conventional broadband patch antennas of more than 20%. Meanwhile, by using a differentially-driven signal along with the introduced feeding scheme, symmetric radiation patterns, low cross-polarization levels and stable radiation patterns are realized within the band. More importantly, the antenna has a stable gain at 8.5 dBi within a wide frequency range, demonstrating the high stability of the radiation characteristics for the two radiation modes. Analysis and parametric studies of the proposed feeding structure are provided.     

宽带平板天线的设计与仿真

基于CST软件设计了一种宽带平板天线,在由4个偶极子组成的阵列下方放置一块金属反射板形成定向天线,通过在平板上采用周期结构反射器来扩大天线的带宽,并结合这种方法,设计了工作在760 MHz～1220 MHz的大线,在此频段内VSWR ＜2,增益高达10.5 dBi.该天线的带宽很宽,且定向性很好,具有广阔的应用前景.     

Design of CPW-fed asymmetric slot UWB antenna for wireless application

A compact Ultra-WideBand(UWB) slot antenna is presented in this paper. The slot is modified rectangular in shape and asymmetrically cut in the ground plane. A hexagonal patch with two stepped CoPlanar Waveguide(CPW) feed is used to excite the slot. Wider impedance bandwidth is achieved due to the extra inductive reactance created by the asymmetric slot which neutralizes the capacitive reactance of the hexagonal patch. The measured impedance bandwidth of the proposed antenna is 11.85 GHz(2.9–14.75 GHz). The radiation patterns of the proposed antenna are obtained and found to be omni-directional in H-plane and bi-directional in E-plane.     

Printed Wide-Slot Antenna for Wideband Applications

The design and analysis of a novel printed wide-slot antenna, fed by a microstrip line, for wideband communication systems is presented. Detailed simulation and experimental investigations are conducted to understand its behavior and optimize for broadband operation. The designed antenna has a wide operating bandwidth of over 120% (2.8-11.4 GHz) for S11 <-10 dB. In addition to being small in size, the antenna exhibits stable far-field radiation characteristics in the entire operating bandwidth, relatively high gain, and low cross polarization. By properly choosing the suitable slot shape, selecting similar feed shape and tuning their dimensions, the design with very wide operating bandwidth, relatively small size and improved radiation pattern is obtained. A comprehensive parametric study has been carried out to understand the effects of various dimensional parameters and to optimize the performance of the designed antenna. Results show that the impedance matching of this kind of antenna is greatly affected by the feed-slot combination and feed gap width, with the slot shape being a main contributor of the radiation characteristics. The simulated and measured Results for return loss, far-field E and H-plane radiation patterns, and gain of designed antenna are presented and discussed.     

Broadband RFID tag antenna with quasi-isotropic radiation pattern

A passive RFID tag antenna in the UHF band using two bent dipoles and a modified double T-matching network is proposed. The antenna was fabricated with a thin copper layer printed on a 50 /spl mu/m-thick PET substrate for low-cost production. The proposed antenna provided a quasi-isotropic radiation pattern and a fairly broad bandwidth S/sub 11/<-10 dB, 8.5%) for conjugate-matching with a commercial tag chip. The efficiency of the antenna was about 90% in the operating frequency band. The measured readable range was between 170 -240 cm for an arbitrary rotation angle of the tag.     

A wide bandwidth and wide beamwidth CDMA/GSM base station antenna array with low backlobe radiation

A wide bandwidth and wide beamwidth L-probe-fed patch antenna array with a novel design of grounded structure is proposed and tested. The antenna is made of stacked patches supported by plastic screws. The patches are proximity fed via L-shaped probe. By cutting slots in two vertical side walls of a box-shaped grounded structure, an impedance bandwidth larger than 20% (SWR<1.5), an H-plane beamwidth over 90/spl deg/, and much reduction in backlobe radiation can be obtained. Details of the proposed antenna, simulation, and experimental results are presented and discussed.     

Circularly polarized feed for cylindrical parabolic reflector antennas

The feed design described is a linear array of crossed dipoles above a ground plane. The radiation patterns of the longitudinal and the transverse dipoles are made equal by parallel longitudinal rods, referred to as beam forming rods or beam matching rods. When used as a circularly polarized feed for an offset parabolic cylinder antenna, aperture efficiencies (spillover included) as high as 0.89 are potentially available if the field distribution along the array is uniform. The beam patterns of the feed were computed both by the method of moments and the geometrical theory of diffraction and are compared with patterns measured on a model at 1.5 GHz. A method of matching the impedance for both linear polarizations is proposed using parallel impedance matching rods.     

A low profile circularly polarized UWB antenna with integrated GSM band for wireless communication

A novel monopole antenna with wide impedance bandwidth and axial ratio bandwidth (ARBW) is presented. The proposed structure is consisting of a wide slot hexagonal shape with an L-shaped radiator coupled inside the slot. Further, two inverted L-shaped strips are protruded on the opposite corners of the hexagonal patch for better radiation capability. The radiating patch is fed by a semi hexagonal ring feed mechanism followed by a tapered line coplanar waveguide (CPW) for improving antenna performance. The proposed structure is supported by a triangular shaped ground plane. An extremely wide -10 dB impedance bandwidth of around 195% and 3-dB axial ratio bandwidth of 32.5% is achieved. The designed antenna has stable radiation characteristics within the operating band. Proposed antenna is fabricated on FR4 epoxy substrate by means of standard photolithography process and measured results are found in a good match with simulated.     

A miniature UWB planar monopole antenna with 5-GHz band-rejection filter and the time-domain characteristics

A planar monopole antenna with a staircase shape and small volume (25/spl times/26/spl times/1 mm/sup 3/) is proposed in this paper. With the use of a half-bowtie radiating element, the staircase-shape, and a modified ground plane structure, the proposed antenna has a very wide impedance bandwidth measured at about 11.6 GHz (2.9-14.5 GHz, bandwidth ratio about 1:5) below VSWR 2 including the WLAN band notched in the vicinity of 5 GHz. An omnidirectional radiation pattern is obtained. The group delay which is an indication of linearity between two proposed antennas is less than 1 ns. The electrical characteristics in terms of frequency and time domains and physical ones of the proposed antenna make it attractive for use in ultrawideband (UWB) systems.     

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。     

An Investigation of Printed Franklin Antennas at X-Band Using Artificial (Metamaterial) Phase-Shifting Lines

Non-radiating artificial phase-shifting lines are constructed using conventional positive-refractive-index (PRI) transmission lines (TL) and the recently developed negative-refractive-index (NRI) transmission lines. The two types of fully printed artificial lines are used to implement microstrip Franklin antennas. The aim is to provide co-phase excitation to an array of half-wavelength dipoles, which generate a broadside beam at the design frequency. The proposed antenna structures not only retain the benefits of previously published designs but also feature a smaller footprint in the transverse direction. Between the two proposed antenna configurations, the PRI-TL based design allows broadside radiation with minimal beam squinting, while the NRI-TL based design provides a frequency steerable beam. A 14-element antenna array for each configuration is characterized using an intuitive TL model, and the study is experimentally verified at 12 GHz. The measured radiation patterns, directivity, gain, and beam-scanning capability are presented.     

宽带高增益圆极化天线

设计了一种宽带高增益圆极化天线。天线采用双同轴线激励以及威尔金森功分器和90°相位比较器的馈电网络形式实现了天线的宽带圆极化特性。该馈电网络形式能在较宽的频带范围内保持稳定的幅度和相位。通过在蝶形天线外围引入方形环,增加了天线的有效辐射面积,从而显著提高了天线的增益。测试结果显示,该圆极化天线VSWR<1.5的阻抗带宽达到63.6%,3 dB轴比带宽达到66.7%,且在1.1~1.6 GHz频段范围内,右旋圆极化增益＞9.4 dB。     

单兵通信系统头盔天线研究进展

头盔天线是指以特殊的人工结构或材料共形到单兵可穿戴头盔上的一种天线,它是单兵无线通信系统中的核心器件。当前的头盔天线研究仅关注辐射全向性、大宽带、高增益和低比吸收率(SAR)中的某一方面或两个方面,难以满足快速发展的战术通信要求。近年来各种基于人工磁导体、超构材料等新型材料/结构的天线设计和阻抗匹配方法被相继提出,使得头盔天线有望突破增益、带宽、尺寸、重量和电磁辐射之间相互制约的技术难题。该文旨在通过系统总结国内外对于头盔天线在控制辐射方向、扩展带宽、增益提高、抑制比吸收率的研究进展之基础上,展望未来头盔天线重点突破的技术方向,并提出一种基于非福斯特电路的圆形阵列头盔天线技术构想。     

On the design of square shape fractal antenna with matching strip for UWB applications

This article presents the design of ultra wide band (UWB) square shape fractal antenna with matching strip. The impedance matching of this proposed antenna is achieved using the metal strip in ground plane at angle 60° from the centre of the patch. The experimental results of this antenna exhibit the ultra wide band characteristics from 2.355?GHz to 15.0?GHz corresponding to 145.722% impedance bandwidth. The proposed antenna has been simulated using 3D-Electromagnetic software. The experimental and simulated results are in good agreement. The measured radiation patterns of this antenna are nearly omni-directional in H-plane and bidirectional in E-plane. This antenna can be useful for transmission of high data rate wireless communications, medical imaging and other UWB applications.     

基于紧耦合结构的宽带基站天线设计

随着5G移动通信频段的公布,传统基站天线已不足以覆盖其工作频段。文章以紧耦合阵列天线理论为基础,提出了一种基于紧耦合结构的交叉偶极子宽带基站天线。该天线由两对正交的领结状偶极子天线构成,通过两对交叉偶极子之间的耦合效应,有效地展宽了天线的阻抗带宽。同时,通过在天线和金属反射板之间加载电阻型频率选择表面,吸收由反射板引入的谐振反射波,改善天线高频端辐射性能。仿真及测试结果表明:该天线在1.7-3.6 GHz 频率范围内,可以满足基站天线的设计指标,两端口驻波比均小于1.5,两端口之间隔离度大于55 dB,半功率波束宽度满足65°±5°范围,且整个频段内增益均大于8.5 dBi。