Truncated spherical helical antennas

The truncated spherical helix is presented as a compact circularly polarised antenna with relatively high gain and moderate bandwidth. A numerical investigation into the radiation properties of this antenna is also presented. The antenna provides a directivity of >9 dB and an axial ratio of <3 dB over a 10% bandwidth. The radiation pattern has a broad main beam and better than 20 dB front-to-back ratio     

A dual polarized aperture coupled circular patch antenna using a C-shaped coupling slot

The design and development of a dual linearly polarized aperture coupled circular microstrip patch antenna at C-band are presented. The antenna uses a novel configuration of symmetric and asymmetric coupling slots. Variations in isolation between orthogonal feedlines and antenna axial ratio with the position of coupling slots are studied and broadband isolation and axial ratio are achieved. The prototype antenna yields 7.6 dBi peak gain, 70/spl deg/ 3-dB beam width, 25 dB cross-polarization levels and an isolation better than 28 dB between the two ports. With an external quadrature hybrid coupler connected to the two orthogonal feedlines, the antenna yields 3-dB axial ratio bandwidth of more than 30% at 5.8 GHz.     

A 94-GHz aperture-coupled micromachined microstrip antenna

This paper presents an aperture-coupled micromachined microstrip antenna operating at 94 GHz. The design consists of two stacked silicon substrates: (1) the top substrate, which carries the microstrip antenna, is micromachined to improve the radiation performance of the antenna and (2) the bottom substrate, which carries the microstrip feed line and the coupling slot. The measured return loss is -18 dB at 94 GHz for a 10-dB bandwidth of 10%. A maximum efficiency of 58±5% has been measured and the radiation patterns show a measured front-to-back ratio of -10 dB at 94 GHz. The measured mutual coupling is below -20 dB in both E- and H-plane directions due to the integration of small 50-μm silicon beams between the antennas. The micromachined microstrip antenna is an efficient solution to the vertical integration of antenna arrays at millimeter-wave frequencies     

Broadband printed circularly-polarised aperture antenna array for millimetre-wave gigabit applications

A simple and successful design of a printed aperture antenna array is presented in view of high-speed millimetre-wave wireless access applications. The antenna element design is based on a broadband travelling- wave aperture antenna for circularly-polarised radiation. For the antenna array design, the sequential rotation scheme is employed for improving the co-polarised gain and axial ratio. The presented antenna array is designed in the 40?48 GHz band and implemented with a 5mil-thick RT/Duroid-5880 PCB. Promising performances are achieved, including a return loss (,10 dB) bandwidth of 32%, an axial ratio (,3 dB) bandwidth of 25%, and a co-polarised gain (flatness , 3 dB) bandwidth of 32% with a maximum gain of 11dBic.     

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.     

ALPSS: a millimetre-wave aperture-coupled patch antenna on asubstrate lens

The feasibility of millimetre-wave (MM-wave) aperture-coupled patch antennas, printed at the back surface of substrate-lenses is demonstrated and the corresponding radiation characteristics are investigated. A specific realisation of such an air-lens-patch-slot-strip (ALPSS) antenna on a low-permittivity ϵ _r=4.0 extended hemispherical lens substrate is theoretically and experimentally characterised at 70 GHz. It is demonstrated that the ALPSS antenna exhibits clean, axially symmetric patterns of low cross-polarisation (26 dB), a directivity of 30.4 dB and the 3 dB pattern full-beamwidth remains within 6°-5° between 60-80 GHz. In addition, a very-high front-to-back (F/B) ratio, of the order of 50 dB is measured at 70 GHz, despite the absence of a backing ground-plane. The ALPSS antenna is well suited for low-cost broadband point-to-point communications and collision avoidance applications     

高温超导圆极化微带天线辐射性能的研究

本文设计并研制了2GHz敷铜板圆极化微带天线及4.5GHz高温超导(HTS)圆极化微带天线.2GHz敷铜板圆极化微带天线的半功率角为63°,最好轴比为1.2dB;4.5GHz的HTS圆极化微带天线相对于银天线有3dB的增益改善,其半功率角大于63°.     

Analysis and measurements for improved crank-line antennas

This paper describes the radiation characteristics of crank-line antennas radiating a circularly polarized wave. First, the radiation efficiency versus substrate permittivity is evaluated. Second, a 12-cell crank-line antenna of substrate permittivity ε_r=1 and antenna height B=λ_11.85 is investigated as a reference antenna, where λ_11.85 is the wavelength at a frequency of 11.85 GHz. It is found that the main beam direction of the reference antenna varies 7° over a frequency range of approximately 6%, with an axial ratio of less than 3 dB and a gain of approximately 21 dB. Third, attention is paid to the gain behavior versus the antenna height. A way to increase the gain by modifying the antenna height is proposed. An increase of 1.5 dB from the gain of the reference antenna is demonstrated. Finally, the axial ratio, gain, and decoupling factor for crank-line antenna arrays are presented and discussed     

一种RFID小型圆极化四臂螺旋天线

设计了一种用于UHF频段射频识别系统的小型右手圆极化四臂螺旋天线。天线由印制在微带介质板的4个长条形臂组成,通过微带功分器馈电。天线在进行4个端口的单独匹配和功分器相连时,需采用一种新的匹配方法。通过仿真优化,天线尺寸为60 mm×60 mm×6 mm,峰值增益为3.8 dB,带内轴比＜3 dB,3 dB波束宽度＞120°,前后比＞15 dB。实物测试结果与仿真结果吻合。     

基于基片集成波导(SIW)的低副瓣阵列天线设计

基片集成波导(SIW)因其低插损、易于加工等特性,在微波天线领域受到了广泛关注.本文应用SIW技术设计了一个Ku波段20元并联馈电的低副瓣线阵天线.实测结果表明在6%的带宽内,其VSWR＜1.5,可以实现-27dB以下副瓣电平及高于18.7dB的增益.此天线应用了改进的维尔瓦迪辐射单元,有效抑制了单元间的互耦,其功分器...     

一种具有高隔离度的双频双圆极化卫星通信天线

 提出了一种新型的用于卫星通信的双频双圆极化多层微带贴片天线.该天线采用兰格耦合器正交馈电,分别在420±1.5MHz和450MHz±1.5MH的收发频率实现右旋和左旋圆极化辐射,且满足单一天线收发双工的通信要求;采用耦合贴片馈电方式和附加集总电路滤波网络,有效地改善了两端口之间的收发隔离度.此外,该天线采用高介电常数的介质基板减小了天线尺寸.兰格耦合器采用曲折线技术减小了馈电网络的结构尺寸(约74.6%).仿真和实测结果吻合良好,在工作频带内收发隔离度大于40dB,VSWR小于2.0,增益大于3dBc,0dB增益宽度及3dB轴比宽度均达到80°.     

Low cross-polarised patch antenna with single feed

A probe-fed patch antenna that generates low cross-polarised radiated fields is presented. The probe is located in the centre of the patch conductor and a microstrip line within the patch is used to ensure that good impedance matching is achieved. Enhanced radiation performance of the printed antenna is demonstrated by theoretically and experimentally investigating a circularly polarised (CP) version of the probe-fed patch antenna and comparing the results with a conventional probe-fed CP patch. The new radiator has an axial ratio of less than 1.5 dB at broadside and a 3 dB axial ratio beamwidth of close to 200deg     

一种可用于卫星导航抗干扰天线的降耦方法

针对基于功率倒置算法的空时自适应抗干扰技术中天线阵元间互耦误差严重恶化算法性能这一问题,分析比较了目前常见的应对解决方案,并提出一种新的可用于抗干扰卫星导航终端的天线阵列降耦方法。该方法通过在卫星导航抗干扰天线阵列中加载电磁谐振吸波器,降低天线阵元间互耦。实验数据表明,利用该方法可以使阵元间互耦降低10 dB,使抗干扰接收机最大抑制干信比提升5 dB。     

A 24-GHz high-gain Yagi-Uda antenna array

A compact 24-GHz Yagi-Uda antenna has been developed using standard design tables and simple scaling to take into account the added capacitance due to the supporting dielectric substrate. The antenna results in a directivity of 9.3 dB, a front-to-back ratio of 11 dB, and a bandwidth of 2.5-3%. The Yagi-Uda antenna has been implemented in an 11-beam system using a planar array and a 2-inch Teflon spherical lens. The measured patterns show a 22 dB gain beam, a cross-polarization level of -24 dB, and a crossover level of -6 dB. The design method presented in this paper is quite straightforward, and can be used to develop low-, medium-, and even high-gain endfire Yagi-Uda antennas.     

一种基于5G应用的圆极化微带相控阵天线

本文提出一款应用于5G频段,可实现方位面±40°波束扫描的圆极化微带相控阵天线。该相控阵天线单元是由矩形贴片、上下介质板、缝隙耦合馈电结构、金属反射板构成。利用切比雪夫综合法的一分八不等分功分器实现相控阵天线的馈电形式。测试结果表明,阵列天线的驻波比带宽为3.25 GHz～3.69 GHz,端口隔离度大于25 dB,扫描过程中增益最大为21 dB,增益衰落小于3 dB,最大扫描角处轴比为2.89 dB。该天线具有低剖面、高隔离度、高增益以及良好的波束扫描性能等优点。     

Dual-polarized slot-coupled planar antenna with wide bandwidth

A new dual-polarized slot-coupled microstrip patch antenna is presented, which can achieve high-isolation, low cross-polarization levels, a wide bandwidth, and low backward radiation levels. The coupling slot is an H-shaped slot. For wide bandwidth and easy integration with active circuits, it uses slot-coupled stacked microstrip patches. The theoretical analysis is based on the finite-difference time-domain (FDTD) method. First, a parametric study on the input impedance of the antenna with a single input port is presented. Based on the results, a dual-polarized microstrip antenna is designed, fabricated, and then measured. The measured return loss exhibits an impedance bandwidth of over 20.9% and the isolation between two polarization ports is better than 36 dB over the bandwidth. The cross-polarization levels in both E and H planes are better than 22 dB. The front-to-back ratio of the antenna radiation pattern is better than 21 dB. Both theoretical and experimental results of return loss, isolation, and radiation patterns are presented and discussed.     

Quadrifilar loop antenna

A new quadrifilar antenna has been developed for generating circularly polarized backfire radiation. The antenna consists of two orthogonal rectangular conducting loops, each incorporating capacitive coupling and fed using either a single or two coaxial cables. Though the geometry is much simpler than a conventional quadrifilar helix antenna, the radiation pattern performance is very similar. Measured and simulated patterns are compared for two antennas with different feed arrangements. It is shown that the resonant structure can produce a cardioid pattern with a directivity of 4.5 dB (120/spl deg/ 3 dB beamwidth) and a front-to-back ratio of more than 20 dB at the center operating frequency. A 10% impedance bandwidth (VSWR<2) over which the axial ratio is less than 3 dB is demonstrated.     

A crank-line array antenna radiating a circularly polarized wave

An array antenna composed of crank-line elements is investigated on the basis of the element current distributions determined by the method of moments. A technique of gradually increasing the antenna height above the ground plane is adopted to enhance the gain. It is found both numerically and experimentally that a gain of approximately 30 dB is obtained with an axial ratio of less than 3 dB over a frequency bandwidth of 2.5%     

一种工作于UHF频段的宽频带互补天线设计

本文应用互补天线的原理,通过采用蝶形平面天线作为电偶极子,采用垂直壁与接地面作为等效磁偶极子,设计了一种新颖的蝶形宽频带天线.该天线实现了62%的相对带宽(1.52-2.89GHz,S11<-10dB),在工作频段内具有稳定的波瓣图,优于-30dB的交叉极化和超过18dB的前后比.     

一种紧凑型双圆极化有源接收天线设计

设计了一种S波段紧凑型双圆极化有源接收天线,该有源接收天线将微带贴片天线与90°混合电桥、低噪声放大器集成设计,既实现了有源天线的整体小型化又提高了各器件间的连接效率;并通过背馈玻璃绝缘子和一种半差分的方式馈电,在改善微带贴片天线方向图对称性的同时,简化了传统差分式馈电的复杂结构.仿真和实测结果表明,该有源接收天线在2.2~2.3 GHz内端口驻波比小于1.47,噪声系数小于0.73 dB,主瓣内轴比小于2.4 dB,G/T值大于-13.9 dB/K,与已有公开文献的有源接收单元天线相比,在保持结构紧凑的同时,其G/T值有较大幅度提升.