一种宽带圆极化缝隙天线的研究与设计

设计了一种结构简单的宽带圆极化缝隙天线,由单层介质基板和两层金属构成,覆盖WiMAX、WLAN和5G通信的sub6 GHz频段。通过在方形缝隙拐角处分别添加两个矩形贴片和一个倒L枝节,实现宽带圆极化辐射。天线采用微带耦合馈电的方式,通过调整T形微带馈线的长度和矩形贴片的宽度,进一步展宽了天线的带宽。测试结果表明,天线的-10 dB阻抗带宽为1.91～7.14 GHz,轴比带宽为2.5～6.3 GHz,相对轴比带宽为86.4%,峰值增益在5.5 GHz处达到5.5 dBic。     

适用于5G通信系统的宽带圆极化缝隙天线

本文设计了一种结构简单的宽带圆极化缝隙天线.通过L形枝节激励接地板上的缝隙产生圆极化辐射,采用倒叉形缝隙结构实现天线的宽频带特性,在L形枝节上切角,提高了天线的轴比带宽;另外,在L形枝节和叉形缝隙做倒角,改善了天线的阻抗匹配,使得天线的圆极化带宽得到进一步扩展.天线的尺寸为60 mm2×60 mm2(0.28λ0×0....     

基于人工磁导体表面的低剖面Fabry-Perot谐振腔天线设计

该文基于人工磁导体表面(Artificial Magnetic Conductor,AMC)设计了一款工作在7 GHz的新型低剖面Fabry-Perot谐振腔天线.该天线采用带金属接地板的矩形微带贴片天线作为初级馈源,由同轴探针进行馈电.以单层双面印制AMC表面作为天线的部分反射层,所设计AMC表面共包含8×8个均匀阵...     

宽波束十字下垂振子圆极化天线的设计

通过对一般十字振子圆极化天线波束宽度和轴比的分析,提出对下垂十字振子加金属套筒,并使用开槽同轴进行同相馈电,改变振子臂长获得宽波束圆极化波的方法。经过HFSS软件的仿真和优化得到两对振子的臂长,同轴的高度,以及金属套筒的最佳尺寸,使波束宽度最宽可以达到140度以上,并且轴比在俯仰角110度范围内都小于4dB,有很好的宽波束圆极化性能。     

用于卫星通信的S波段宽带圆极化微带天线阵设计方法

提供了一种用于卫星通信的S波段宽带圆极化微带天线阵的设计方法,采用口径耦合馈电,利用连续相位旋转法实现圆极化工作,并增加空气基板展宽其工作带宽。在此设计基础上制作了天线阵实物,实测VSWR1.5的阻抗带宽为23.8%,最大增益为14.5dB。     

一种平面宽带单极天线的设计

设计一种新颖的平面宽带单极天线。该天线由矩形平板单极天线变形而来,通过U形槽、增加和折叠天线两臂,实现小型化、多模和低驻波比特性(在1.71～1.96GHz和2.38～6.37GHz频段内VSWR小于2)。通过CST软件进行仿真,分析各谐振的电流分布和谐振长度。该天线结构简单,尺寸较小(60mm×20mm),制作容易,可用于GSM/WLAN/WIMAX应用。通过加工测试,天线的仿真结果和实测结果非常吻合。     

基于线分量幅度的圆极化天线测试方法的修正

本文讨论了基于线分量幅度的圆极化天线测试方法,介绍了这种方法测试轴比的原理,首次指出了这种方法不能判定主极化旋向的问题,并提出了采用两个一般性能的圆极化参考天线来判定旋向的修正方案.此外针对实际测试中的特殊情况进行了修正完善.最后实际测量了自行设计的双频双圆极化天线阵列,测试与仿真结果保持了良好的一致性,从而表明了该修正的正确性、有效性与实用性.     

一种基于多模谐振的宽带贴片天线设计

设计了一种基于多模谐振的宽带贴片天线.首先,通过在一个矩形贴片上蚀刻两条缝隙的方式,使天线同时工作在TM₁₀和反相TM₃₀两个正交的模式来展宽天线的带宽;其次,通过在辐射贴片左右两侧的顶角处蚀刻4个方形缝隙,改善天线低频处的阻抗匹配,有效激励起缝隙模式,进一步展宽天线的工作带宽;为了激励这3个工作模式,天线采用缝隙耦合馈电方式,同时在微带馈线的终端加载方形贴片,来改善天线的阻抗匹配.测量和仿真结果吻合良好,天线的工作频带为2.09 GHz～2.77 GHz,相对带宽为27.9%.天线实现了良好的宽边辐射,峰值增益达到了6.3 dBi.     

用于静电放电辐射场测试的V型偶极子宽带天线

对静电放电特点和几种瞬变场的相关测试天线进行了分析,针对静电放电辐射场测试技术中的难点和热点问题,作者研制了电阻加载V型偶极子宽带天线.实验表明,结构合理、加载择优的V型偶极子天线具有宽频带、快响应、小失真的特点,能够满足静电放电电磁脉冲场的测试要求.     

A Compact Flexible Circularly Polarized Implantable Antenna forBiotelemetry Applications

With the help of in-body antennas, the wireless communication among the implantable medical devices (IMDs) and exterior monitoring equipment, the telemetry system has brought us many benefits. Thus, a very thin-profile circularly polarized (CP) in-body antenna, functioning in ISM band at 2.45 GHz, is proposed. A tapered coplanar waveguide (CPW) method is used to excite the antenna. The radiator contains a pentagonal shape with five horizontal slits inside to obtain a circular polarization behavior. A bendable Roger Duroid RT5880 material (ε_r = 2.2, tanδ = 0.0009) with a typical 0.25 mm-thickness is used as a substrate. The proposed antenna has a total volume of 21 × 13 × 0.25 mm³. The antenna covers up a bandwidth of 2.38 to 2.53 GHz (150 MHz) in vacuum, while in skin tissue it covers 1.56 to 2.72 GHz (1.16 GHz) and in the muscle tissue covers 2.16 to 3.17 GHz (1.01 GHz). GHz). The flexion analysis in the x and y axes was also performed in simulation as the proposed antenna works with a wider bandwidth in the skin and muscle tissue. The simulation and the curved antenna measurements turned out to be in good agreement. The impedance bandwidth of −10 dB and the axis ratio bandwidth of 3 dB (AR) are measured on the skin and imitative gel of the pig at 27.78% and 35.5%, 13.5% and 4.9%, respectively, at a frequency of 2.45 GHz. The simulations revealed that the specific absorption rate (SAR) in the skin is 0.634 and 0.914 W/kg in muscle on 1g-tissue. The recommended SAR values are below the limits set by the federal communications commission (FCC). Finally, the proposed low-profile implantable antenna has achieved very compact size, flexibility, lower SAR values, high gain, higher impedance and axis ratio bandwidths in the skin and muscle tissues of the human body. This antenna is smaller in size and a good applicant for application in medical implants.     

Compact Interlaced Dual Circularly Polarized Sequentially Rotated Dielectric-Resonator Antenna Array

In this study, a compact 2 × 2 interlaced sequentially rotated dual-polarized dielectric-resonator antenna array is proposed for 5.8 GHz applications. The array is composed of a novel unit elements that are made of rectangular dielectric resonator (RDR) coupled to an eye slot for generating the orthogonal modes, and to acquire circular polarization (CP) radiation. For the purpose of miniaturization and achieving dual polarized resonance, the array is fed by two interlaced ports and each port excites two radiating elements. The first port feeds horizontal elements to obtain left hand circular polarization (LHCP). The second port feeds vertical elements to obtain right hand circular polarization (RHCP). A quarter-wave length transformer is employed to reduce the attenuation and consequently increase the array gain performance. The 35 × 35 mm² () gains were 8.4 and 8.2 dBi for port 1 and port 2, respectively, with port isolations of −33.51 dB. The design achieves a voltage standing-wave ratio (VSWR) < −10 dB and an axial ratio (AR) ˂ − 3 dB bandwidth of 2.48% (5.766 to 5.911 GHz) for LHCP at port 1 and a VSWR < −10 dB and AR ˂ −3 dB bandwidth of 2.28% (5.788 to 5.922 GHz) for RHCP at port 2. The findings of the proposed design validate its use for ISM band applications.     

一种星载Ka频段圆极化振子天线阵列设计

针对Ka频段卫星通信系统的需求,设计了一种应用于卫星通信的星载Ka频段圆极化振子天线阵列.天线单元采用非对称双臂振子单元形式,十字交叉振子采用自相移结构来实现圆极化.天线阵列采用三角形排布的方式,通过调整布阵时天线单元旋转相位,来实现阵列的右旋圆极化.仿真结果表明：天线阵列驻波比除阵面四周由于边缘效应引起的驻波比偏大外,其余都小于1.5;天线阵列的轴比小于2.3 dB;扫描60°时,天线增益下降小于5 dB,表明天线阵列具有较高辐射功率.该天线阵列可作为相控阵天线的馈源,在卫星通信系统具有良好的应用前景.     

Triple-Band Circularly Polarized Dielectric Resonator Antenna (DRA) for Wireless Applications

This paper proposes a new dielectric resonator antenna (DRA) design that can generate circularly polarized (CP) triple-band signals. A triple-band CP DRA antenna fed by a probe feed system is achieved with metal strips structure on side of DRA structure. The design start with conventional rectangular DRA with F shaped metal strips on DRA structure alongside the feed. Then, the F metal strip is enhanced by extending the length of the metal strip to obtain wider impedance bandwidth. Further improvement on the antenna performance is observed by improvised the conventional DRA structure. The method of removing part of DRA bottom resulted to higher antenna gain with triple band CP. The primary features of the proposed DRA include wide impedance matching bandwidth (BW) and broadband circular polarization (CP). The primary features of the proposed DRA include wide impedance matching bandwidth (BW) and broadband circular polarization (CP). The CP BW values recorded by the proposed antenna were ∼ 11.27% (3.3–3.65 GHz), 12.18% (4.17–4.69 GHz), and 1.74% (6.44–6.55 GHz) for impedance-matching BW values of 35.4% (3.3–4.69 GHz), 1.74% (5.36–5.44 GHz), and 1.85% (6.41–6.55 GHz) with peak gains of 6.8 dBic, 7.6 dBic, and 8.5 dBic, respectively, in the lower, central, and upper bands. The prototype of the proposed antenna geometry was fabricated and measured. A good agreement was noted between the simulated and the measured results.     

Endowing Perovskite Nanocrystals with Circularly Polarized Luminescence

Perovskite nanocrystals are attracting great interest due to their excellent photonic properties. Here, through a supramolecular self‐assembly approach, the perovskite nanocrystals (NCs) with a novel circularly polarized luminescence (CPL) are successfully endowed. It is found that the achiral perovskite NCs can coassemble with chiral gelator in nonpolar solvents, in which the gelator molecules modify the surface of the perovskite NCs. Through such cogelation, the molecular chirality can transfer to the NCs resulting in CPL signals with a dissymmetric factor (g_lum) up to 10^?3. Furthermore, depending on the molecular chirality of the gelator, the CPL sense can be selected and the mirror‐imaged CPL is obtained. Such gels can be further embedded into the polymer film to facilitate flexible CPL devices. It is envisaged that this approach will afford a new insight into the designing of the functional chiroptical materials.     

Metasurface-Enabled Generation of Circularly Polarized Single Photons

Single photons carrying spin angular momentum (SAM), i.e., circularly polarized single photons generated typically by subjecting a quantum emitter (QE) to a strong magnetic field at low temperatures, are at the core of chiral quantum optics enabling nonreciprocal single-photon configurations and deterministic spin-photon interfaces. Here, a conceptually new approach to the room-temperature generation of SAM-coded single photons (SSPs) is described, which entails QE nonradiative coupling to surface plasmons being transformed, by interacting with an optical metasurface, into a collimated stream of SSPs with the designed handedness. Design, fabrication, and characterization of SSP sources, consisting of dielectric circular nanoridges with azimuthally varying widths deterministically fabricated on a dielectric-protected silver film around a nanodiamond containing a nitrogen-vacancy center, are reported. With properly engineered phases of QE-originated fields scattered by nanoridges, the outcoupled photons are characterized by a well-defined SAM (with the chirality >0.8) and high directionality (collection efficiency up to 92%).     

Enantiomeric MOF Crystals Using Helical Channels as Palettes with Bright White Circularly Polarized Luminescence

The host–guest chemistry of metal–organic frameworks (MOFs) has enabled the derivation of numerous new functionalities. However, intrinsically chiral MOFs (CMOFs) with helical channels have not been used to realize crystalline circularly polarized luminescence (CPL) materials. Herein, enantiomeric pairs of MOF crystals are reported, where achiral fluorophores adhere to the inner surface of helical channels via biology-like H-bonds and hence inherit the helicity of the host MOFs, eventually amplifying the luminescence dissymmetry factor (g_lum) of the host l /d -CMOF (±1.50 × 10⁻³) to a maximum of ±0.0115 for the composite l /d -CMOF⊃fluorophores. l /d -CMOF⊃fluorophores in pairs generate bright color-tunable CPL and almost ideal white CPL (0.33, 0.32) with a record-high photoluminescence quantum yield of ≈30%, which are further assembled into a white circularly polarized light-emitting diode. The present strategy opens a new avenue for propagating the chirality of MOFs to realize universal chiroptical materials.