一种低剖面可重构全向圆极化天线的设计

本文提出了一种低剖面极化可重构全向圆极化天线。该天线由一个1×4偶极子阵列天线和一个单极子天线组成,通过设计可重构馈电网络来激励这两部分子天线,可产生左右旋可切换的全向圆极化波。设计的馈电网络主要由一单刀双掷开关电路和一紧凑二阶3dB耦合器组成,从而可输出幅度相等、相位差可在±90°间切换的两路信号。将馈电网络的两输出端口分别与水平极化的偶极子阵列天线和垂直极化的单极子天线相连,便可使天线在左旋圆极化(LHCP)和右旋圆极化(RHCP)两种辐射状态之间切换。设计的天线总体截面积为59.9×59.9×πmm2,天线厚度为0.058λ0。测试结果表明,该天线在左右旋圆极化状态下的阻抗带宽（|S11|＜ -10 dB）分别为21.5%（2.24~2.78GHz）和19.4%（2.32~2.81GHz）。全向左右旋圆极化状态的重叠轴比带宽(AR＜3dB)约为7% (2.44~2.62GHz)。天线的最高增益为-0.9dB,水平面增益波动小于1.3dB。     

一种宽带高低仰角增益的卫星导航终端天线

研究了一种宽频带高低仰角增益的卫星导航终端天线。天线由两对交叉偶极子天线臂、馈电网络和栅栏状反射腔组成;两对交叉偶极子臂分别位于水平面上和垂直面上,形成对上半空间各仰角方向上增益的有效贡献;馈电网络实现交叉偶极子馈电相位相差90°,满足天线的圆极化辐射;栅栏状反射腔实现天线的定向辐射和辅助调整天线的带宽和低仰角增益。分析了典型参数变化对天线性能的影响,测试结果表明,天线|S11 |≤-10 dB 的阻抗带宽1.330~1.810 GHz、轴比小于3 dB 带宽为1.54~1.66 GHz 和在1.561 GHz、1.575 GHz、1.602 GHz 频点10°低仰角最大增益分别为0.35 dBi、0.21 dBi、0.1 dBi。该天线具有高低仰角增益,尺寸小,频带宽的特点。     

单馈点宽带圆极化交叉偶极子天线

基于传统交叉偶极子天线,设计了一款应用于全球定位系统(GPS)的宽带圆极化天线。该天线用一个50 Ω的同轴线给交叉偶极子馈电,通过一对四分之一空置印刷环使振子臂之间形成90°相位差以产生圆极化辐射。为了拓展阻抗带宽和轴比(AR)带宽,在耦合贴片上进行切角、开缝处理。Ansoft HFSS仿真结果显示,阻抗带宽(|S11|<-10 dB)为66.7%(1.141~2.283 GHz),3 dB轴比带宽为33.3%(1.347~1.885 GHz)。在工作频段内最大圆极化增益为8.2 dBi,圆极化特性良好,实现了带宽展宽的目的。     

一种宽带全向圆极化天线简

 基于环天线-偶极子模型,本文提出一种宽带全向圆极化天线.天线包含四对围绕圆柱放置的倾斜振子和一个宽带馈电网络.每对振子包含一个主辐射振子和一个用以增加带宽的寄生振子.馈电网络包括四个宽带巴伦和一个阻抗匹配电路.实验结果表明,该天线15-dB回波损耗带宽和3-dB轴比带宽分别为31%（1.68-2.31GHz）和30%（1.7-2.3GHz）,水平面不圆度小于1dB.     

一种三馈圆极化微带天线的设计与制作

提出了一种应用于无线局域网（WLAN）通信的三馈圆极化微带天线。天线在2300～2600MHz频带内实现圆极化辐射。天线馈电网络采用三功分馈电,增加了轴比带宽;馈电网络和附加的寄生贴片展宽了阻抗带宽;延伸天线介质衬底增大了波束宽度。仿真与实测结果吻合良好。测量结果表明,天线的阻抗带宽达到46.8%（VSWR〈2）,轴比带宽达到12.2%（AR〈3dB）。     

Ku波段宽带高增益基片集成腔圆极化阵列天线北大核心CSCD

提出了一款应用于Ku波段的宽带高增益基片集成腔(Substrate Integrated Cavity,SIC)圆极化阵列天线。通过引入沿SIC口径面对角线放置的一对半月形寄生贴片和SIC底部馈电纵缝,使SIC中的TM_(211)和TM_(121)谐振模式幅值相等、相位相差90°,产生高增益圆极化辐射。同时,双寄生贴片还引入了一种背腔缝隙耦合振子圆极化辐射模式,扩宽了天线高增益圆极化辐射带宽。在此基础上,设计了一款2×2单元顺序旋转馈电的SIC圆极化阵列天线。阵列天线采用双层基片集成波导顺序相移馈电网络进行馈电,进一步增大了天线的圆极化带宽。综合考虑天线的-10 dB反射系数带宽、3 dB轴比带宽和3 dB增益带宽,测试结果表明,圆极化阵列天线的有效带宽为10.74-13.30 GHz(21.3%),在通带范围内最大增益为14.50 dBi。     

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。     

小型化缝隙加载圆极化及宽带微带贴片天线设计

提出了一种十字形缝隙加载的小型宽带及圆极化微带贴片天线的设计方法。该天线通过在方形贴片上加载一个大尺寸的十字形缝隙实现天线的尺寸缩减,介质基片采用由FR4和空气层组成的层叠结构,在缝隙中嵌入L型枝节,只需通过调整枝节上同轴线馈电点的位置来获得圆极化或宽带阻抗匹配。ANSYS HFSS仿真分析表明,天线的圆极化带宽（AR≤3 dB）为1.7%,阻抗带宽（VSWR≤2）为5.8%,天线在宽带范围内具有稳定的增益,峰值增益为7.8 dB,同时贴片面积缩减了52.3%。改变馈电点的位置可调节两个谐振频率使天线阻抗带宽达到9.4%,比传统的微带贴片天线阻抗带宽提高了114%。     

低剖面宽带圆极化天线阵列

基于双馈双线极化微带天线,结合威尔金森功分器、T形结功分器及顺序旋转馈电的优点,设计了一种新型低剖面宽带圆极化2×2天线阵列。把辐射贴片和馈电网络集成在同一介质层,有效地利用了介质空间,降低了天线的剖面,增加了天线的带宽。4个天线单元顺序旋转90°,利用一分四T形结功分器给4个单元等幅、相位依次相差90°馈电。根据Ansoft''s HFSS仿真结果,制作了样机。样机实测结果和仿真结果吻合。实测结果表明,该天线阵驻波带宽可以达到27.78%,3-dB轴比带宽可以达到52%,最大增益为14.19 dB。     

一种应用于三频GPS的宽频带单馈电天线设计

为了实现全球定位系统（global positioning system,GPS）天线小型化并提高其性能,提出了一种新型的三频段GPS宽频带单馈电背腔天线,可在1176.45 MHz（L5）、1227.60 MHz（L2）和1575.42 MHz（L1）三个GPS频段下工作。通过在一端馈送交叉型行波天线并在另一端添加负载,来实现提出天线的右旋圆极化（right-hand circular polarization,RHCP）,且配有弯折线散热器。天线尺寸仅为120×120×29 mm3。仿真和实际测量结果显示,提出的单馈电天线无需使用复杂的馈电网络或双馈结构便可提供宽阻抗带宽（VSWR<2）、低轴比（AR）（<2 dB）和高RHCP增益（>4 dBic）。     

宽带圆极化锥形辐射单元阵列天线的设计

基于L型探针馈电提出了一种宽带圆极化锥形辐射单元天线的设计方法.为了提高轴比带宽,馈电网络应用带L型馈电探针的宽带90°电桥,锥台单元取代普通平面贴片作为辐射单元.4个单元组阵后可得到的峰值增益为12.7 dB.馈电网络在介质基板的底面以此来减小天线总体尺寸.测量结果与仿真结果吻合良好,天线可实现40.1%(VSWR<...     

宽带高增益圆极化微带天线与阵列

设计了一副宽带高增益圆极化微带天线,并进行组阵分析。天线中心频率2.6 GHz,通过增加寄生贴片和空气层来提高天线单元的增益和带宽。上下两层介质板上边长不同的切角方形贴片分别激励一个低频与高频的圆极化模,有效地拓宽了轴比带宽。仿真结果表明,反射系数|S11|<-10 dB带宽21.8%,3 dB轴比带宽12.0%,中心频率点增益9.0 dBi。对天线单元进行加工测试,与仿真结果较为吻合。设计了2×4元阵列,并进行了仿真,增益提升至17.5 dBi,3 dB轴比带宽10.4%。     

Broadband circularly polarised hexagonal slot antenna excited by a tapered microstrip feeder

In this article, a broadband circularly polarised slot antenna fed by a single microstrip line is implemented. The proposed antenna is composed of an unequilateral hexagonal slot to implement circular polarisation and tapered microstrip feeding line to enhance the impedance bandwidth. A conducting reflector is also employed to enhance the antenna gain. The proposed antenna, 60 mm × 60 mm × 18.12 mm in size, was fabricated and tested. The measured??10 dB reflection bandwidth and 3 dB axial ratio bandwidth were 48.9% and 17%, respectively. The measured gain of the fabricated antenna ranged from 5.4 dBi to 6 dBi within an axial ratio bandwidth of 3 dB.     

4-element planar array antenna for UWB application

A novel low-cost 4-element planar array antenna directly fed by a coaxial cable for Ultra-WideBand(UWB) application is presented. The proposed antenna consists of 2×2 bowtie elements and a simple 1:4 power divider feeding network. Compared to the basic bowtie element, the impedance bandwidth of the array antenna has a significant improvement that the low cut-off frequency is extended from 6 GHz of the bowtie element to 2 GHz. The measured results show that the proposed antenna has a large bandwidth of 2 GHz to 11 GHz for Voltage Standing Wave Ratio(VSWR)2, and exhibits a bidirectional radiation pattern and a modest gain across the operating band and a peak gain of about 9 dBi at 11 GHz.     

Circularly polarized dielectric-loaded planar antenna excited bythe parallel feeding waveguide network

A new receiving planar array antenna for DBS (direct broadcasting satellite) is proposed. The element antenna is a short waveguide aperture mounted in the ground plane, loaded with a dielectric and polarizers, and excited through its side wall by another feeding rectangular waveguide. The gain of the element antenna loaded with a dielectric is so high that the grating lobes can be reduced sufficiently even if the element spacing in the array is wider than the wavelength in free space. Therefore we can reduce the number of the array elements, and parallel feeding by the low loss waveguide network can be feasible to provide a planar array antenna. This paper describes the experimental results of several kinds of the circularly polarized dielectric-loaded element antennas and the planar antennas fed by the waveguide network. In the 12 GHz band the planar antenna with 64-element radiators has a maximum gain of 31.9 dBi with an aperture efficiency of 94.7%, the 1 dB-down frequency bandwidth of the gain is about 800 MHz (6.7% for a center frequency of 11.85 GHz), and the frequency bandwidth of the axial ratio is less than 1 dB of 850 MHz (7.2%)     

Evaluation of gain enhancement in improved size microstrip antenna arrays for millimetre-wave applications

A number of microstrip antenna arrays have been designed based on the improved size patch elements with different substrate heights to evaluate the gain enhancement in practical measurements. Initially, microstrip patch antenna arrays (MPAAs) have been designed, analysed and tested at 10 GHz frequency and then the optimised high gain (∼21 dBi) array is fabricated and tested at 60 GHz-band frequencies. It has been found that the loss emergence due to the long feeding transmission line (TL) network severely degrades the antenna gain in large MPAAs on the thicker substrates. However, the gain can be significantly enhanced in large MPAAs by employing relatively thinner substrate but it shrinks the return loss (S11) bandwidth (BW) and increases the side lob level (SLL).     

Array thinning by using antennas in a Fabry-Perot cavity for gain enhancement

A Fabry-Perot cavity (FPC) between a ground plane and a partially reflective surface (PRS) is used here to design array antennas with large distance between the radiating elements. This configuration provides some advantages: i) a reduction of the number of array elements to achieve high directivity; ii) large space between contiguous elements that may host a bulky feeding network as required for dual polarization or active antennas; iii) small coupling and easy feeding network designs because of the smaller number of elements with larger inter-element distance. We show that when designing the FPC antenna a frequency shift of the gain maximum may occur, especially in this sparse array configuration. We also show the existence of preferred distances between elements that controls both the directivity and the side lobe level, and how the presence of the FPC and the relaxed requirement of the interelement distance result in a lower interelement coupling. The presented dual polarized antenna comprises two interleaved 2 /spl times/ 2 arrays placed in a 2-layer FPC, and exhibits a 19 dBi gain and 30 dB of isolation between the two ports over an operating bandwidth of approximately 5.7%, i.e., typical for patch antennas.     

A broadband circularly polarized cavity-backed Archimedean spiral array antenna for C-band applications

In this letter, a new configuration of sequentially rotated circularly polarized (CP) array antenna with a modified gain is investigated. In order to realize the presented antenna, four Archimedean spiral radiators are applied on a substrate, backed by a circularly slotted ground plane. Also a combination of 180° rat-race coupler and 90° branch-line couplers prepare the employed feeding network in this study. Furthermore, cavity-backed structure is utilized to enhance the antenna gain and achieve a directional radiation pattern over the operating frequency band. This configuration also extends the return loss (RL) and the axial ratio (AR) bandwidths, simultaneously. According to the experimental results, the 2 × 2 CP array antenna has RL bandwidth of 64.28%, AR bandwidth of 54.28%, and peak gain of 10.84 dBic. The close correspondence between the measured and the simulated results validates the proposed design.