Effect of Partial Ground Plane Removal on the Radiation Characteristics of a Microstrip Antenna

This study presents a new, simple method for reducing the back-lobe radiation of a microstrip antenna (MSA) by a partially removed ground plane of the antenna. The effect of the partial ground plane removal in different configurations on the radiation characteristics of a MSA are investigated numerically. The partial ground plane removal reduces the backlobe radiation of the MSA by suppressing the surface wave diffraction from the edges of the antenna ground plane. For further improving the front-to-back (F/B) ratio of the MSA, a new soft-surface configuration consisting of an array of stand-up split ring resonators (SRRs) are placed on a bare dielectric substrate near the two ground plane edges. Compared to the F/B ratio of a conventional MSA with a full ground plane of the same size, an improved F/B ratio of 9.7 dB has been achieved experimentally for our proposed MSA.

Stitched Ground Planes for Textile Antenna Application: An Experimental Study

This paper presents an application of stitched ground plane for microstrip patch antenna design. In this work Matlab interface to computer embroidery techniques were used to implement the felt and denim substrates on microstrip patch antenna. These antennas were simulated using a commercial full 3D electromagnetic CST Microwave Studio 2019. A method to optimize the stitch patterns with conductive thread for antenna ground plane for 2.45 GHz industrial, scientific, and medical (ISM) band and 5 GHz wearable wireless local area networks (WLAN) frequencies was achieved. Rigid and flexible wearable antennas (microstrip patch antennas) were fabricated using the stitched ground plane. The electrical resistance was reduced between the meshes during the stitching design process. Results in terms of bandwidth, radiation patterns and reflection coefficients (S11) are presented.

有限大接地板对圆极化微带贴片天线等化波束宽度影响的研究

基于数值仿真和实验测量,研究了接地板尺寸对微带贴片天线圆极化等幅条件的影响规律。结果表明:当接地板尺寸变化时,铅垂极化分量幅度(|E_(θ)|)和水平极化分量幅度(|E_(φ)|)受到地板尺寸变化的敏感度和规律不同,从而影响了圆极化天线主波束范围内保持其幅值相等的条件。最终推得接地板尺寸在0.6~1.0波长范围内,铅垂、水平极化分量保持等幅条件(按幅度差不大于3dB计)的“等化波束宽度”经验公式,为可穿戴圆极化贴片天线的波束宽度调控及选择提供理论依据。

太赫兹天线(一)

文章叙述了天线的作用和辐射电磁波的原理、天线的分类和性能(指标)要求,介绍了一些微波、毫米波和光波中的传统天线在太赫兹天线中的应用。

Review of Large Spacecraft Deployable Membrane Antenna Structures

The demand for large antennas in future space missions has increasingly stimulated the development of deployable membrane antenna structures owing to their light weight and small stowage volume. However, there is little literature providing a comprehensive review and comparison of different membrane antenna structures. Space-borne membrane antenna structures are mainly classified as either parabolic or planar membrane antenna structures. For parabolic membrane antenna structures, there are five deploying and forming methods, including inflation, inflation-rigidization, elastic ribs driven, Shape Memory Polymer （SMP）-inflation, and electrostatic form- ing. The development and detailed comparison of these five methods are presented. Then, properties of membrane materials （including polyester film and polyimide film） for parabolic membrane antennas are compared. Additionally, for planar membrane antenna structures, frame shapes have changed from circular to rectangular, and different ten- sioning systems have emerged successively, including single Miura-Natori, double, and multi-layer tensioning systems. Recent advances in structural configurations, tensioning system design, and dynamic analysis for planar membrane antenna structures are investigated. Finally, future trends for large space membrane antenna structures are pointed out and technical problems are proposed, including design and analysis of membrane structures,materials and processes, membrane packing, surface accuracy stability, and test and verification technology. Through a review of large deployable membrane antenna structures, guidance for space membrane-antenna research and applications is provided.

A new photonic bandgap cover for a patch antenna with a photonic bandgap substrate

A new photonic bandgap (PBG) cover for a patch antenna with a photonic bandgap substrate is introduced. The plane wave expansion method and the FDTD method were used to calculate such an antenna system. Numerical re-sults for the input return loss, radiation pattern, surface wave, and the directivity of the antennas are presented. A com-parison between the conventional patch antenna and the new PBG antenna is given. It is shown that the new PBG cover is very efficient for improving the radiation directivity. The physical reasons for the improvement are also given.

A new patch antenna with metamaterial cover

A metamaterial was introduced into the cover of a patch antenna and its band structure was analyzed. The metama- terial cover with correct selection of the working frequency increases by 9.14 dB the patch antenna’s directivity. The mechanism of metamaterial cover is completely different from that of a photonic bandgap cover. The mechanism of the metamaterial cover, the number of the cover’s layers, and the distance between the layers, were analyzed in detail. The results showed that the metamaterial cover, which works like a lens, could effectively improve the patch antenna’s directivity. The physical reasons for the improvement are also given.

Multiband Monopole Antenna with Sector-Nested Fractal

A kind of novel multi-frequency monopole antenna with sector-nested fractal is proposed and designed, which is nested with a series of similar circular sector elements. By means of the trapeziform ground plane with the tapered CPW (coplanar waveguide) feeder in the middle, the antenna’s radiation performance is greatly improved. The antennas can synchronously operate in three frequencies, covering the working frequency bands of WLAN/WiMAX, 2.44 GHz/3.5 GHz/5.2 GHz - 5.8 GHz. The pattern and impedance measurements of antenna show a good performance over the WLAN/WiMAX band;it possesses a near omni-directional characteristic and good radiation efficiency. Moreover, the antenna is miniature and its design idea can be easily applied into other types of nested structure, the features of which make the proposed antenna have a promising application in other fields.

Design of Integrated Triple Band Notched for Ultra-Wide Band Microstrip Antenna

Ultra-wideband (UWB) is one of the recent topics that received a great concern from academia and industry. However, UWB found many difficulties to be standardized due to the overlay working that made UWB an important potential interference source to many licensed and unlicensed spectrum throughout the band 3.1 to 10.6 GHz. This paper demonstrates the design of integrated triple band notched for UWB Microstrip antenna. We simulated UWB short range systems which require low power and these are built using inexpensive digital components. We proposed a compact triple band notched CPW (Co-planar Waveguide) fed Micro strip Antenna (MSA) for UWB. This band-notched antenna has rejection characteristics at 3.2 GHz (for Wi-MAX band 3.16 to 3.32 GHz), at 5.5 GHz (for WLAN 2 band—5.3 to 5.72 GHz) and at 7.9 GHz (for ITU band 7.72 GHz to 8.13 GHz). The simulation was done using IE3D simulator.

A Compact 28 GHz Millimeter Wave Antenna for Future Wireless Communication

This article presents a novel modified chuck wagon dinner bell shaped millimeter wave(mm-wave)antenna at 28 GHz.The proposed design has ultra-thin Rogers 5880 substrate with relative permittivity of 2.2.The design consists of T shaped resonating elements and two open ended side stubs.The desired 28 GHz frequency response is achieved by careful parametric modeling of the proposed structure.The maximum achieved single element gain at the desired resonance frequency is 3.45 dBi.The efficiency of the proposed design over the operating band is more than 88%.The impedance bandwidth achieved for−10 dB reference value is nearly 2.9 GHz.The proposed antenna is transformed into four element linear array which increases the gain up to 10.5 dBi.The fabricated prototype is tested for the measured results.It is observed that measured results closely match the simulated results.By considering its simple structure and focused radiation patterns,the proposed design is well suited for IoT(Internet of Things),mmWave microwave sensing,5G and future RF(Radio Frequency)frontends.

Design of Miniature UWB-Based Antenna by Employing a Tri-Sectional SIR Feeder

A novel ultra-wideband(UWB)-based microstrip antenna is presented in this work by using a slotted patch resonator,a tri-sectional stepped impedance resonator(SIR)feeder,as well as a reduced ground plane.The whole structure was realized on an FR4 substrate.The impact of incorporating several cases of ground planes on the input reflection has been thoroughly investigated under the same tri-sectional SIR feeder and by employing a slotted patch radiator.Since the complete ground plane presents an inadequate frequency response,by reducing the ground plane,the induced UWB responses are apparent while the antenna exhibits higher impedance bandwidth.The impact of both the uniform impedance resonator(UIR)as well as the SIR feeder on the input reflection has also been examined by following the same adopted reduced ground technique and using a slotted patch radiator.As a result,the UIR feeder exhibits a dual-band frequency response,when a wide notched band is incorporated in the range from 4.5–6.5 GHz.The dual-band response of the bi-sectional SIR feeder is still apparent with a narrower notched band in the frequency range from 4–5 GHz.As far as the tri-sectional SIR feeder is concerned,the UWB response is discernible without recording the existence of a notched band.Additionally,the antenna displays a higher impedance bandwidth compared with the previously reported steps.Our proposed antenna configuration is designed with highly compact dimensions and an overall size of 14×27.2 mm2.Moreover,it operates under the impedance bandwidth of 2.86–10.31 GHz that can be leveraged for numerous applications where wireless systems are used.Our approach presents several advantages compared with the other reported UWB-based antennas in the literature,whereas the measured S11 pattern is in good agreement with the simulated one.

波导通风窗在矿用方舱电磁屏蔽中的应用研究

为满足矿用方舱内外的电磁屏蔽要求,同时保证良好的通风效果,结合截止波导管的高通滤波性能,设计并改进了一种有效的通风窗结构。将多个方形波导管组成波导通风窗,以平面波作为外部干扰源,在0-20GHz频段内仿真分析了开孔面积、开孔数量以及开孔倾角对方舱内部电磁屏蔽效果的影响,结果表明当单个波导结构不变时,增大开孔面积不会提升方舱内部的屏蔽效能;而当开孔面积保持一致时,开孔数量越多,电磁屏蔽效果越好;适当改变开孔倾角能够提升方舱的屏蔽效能。以工作频率为3GHz的半波偶极子天线作为内部干扰源,模拟了方舱内部产生的电磁干扰对舱外环境的影响,结果证明所设计的波导通风窗结构能够很好地阻隔舱内设备产生的电磁干扰。

平面圆极化磁电偶极子天线设计

设计了一种小尺寸平面结构的圆极化(CP)磁电偶极子(ME)天线。该天线由印刷在介质基板上的1/4波长短路贴片与一对平行的电偶极子臂相连组成。天线通过同轴探针进行馈电,短路片最大开口的切向电场可等效为磁流,与电偶极子臂上的电流的相位差约为90°,可获得圆极化的定向辐射模式。通过ANSYS HFSS电磁仿真软件仿真结果表明:|S_(11)|≤-10 dB的阻抗带宽为6.9%(5.57~5.97 GHz),有效带宽内增益为4.15~4.66 dBi,轴比均小于3 dB。天线尺寸较小,结构简单,易于制造,可用于现代无线通信。

平面近场天线测量误差分析

基于平面近场天线测量的基本理论,以半波偶极子阵列天线为模型,利用数值分析的方法研究了平面近场天线测量中的有限扫描面截断误差、位置误差和暗室环境误差对天线方向图副瓣特性的影响;并用自比较法实测了探头和AUT之间多次耦合的影响;给出了有探头补偿时由近场数据确定天线远场方向图的计算公式和OEWG探头的E面和H面方向图。通过与理论结果比较,得出了上述5项误差源产生的误差及其范围,即测量天线方向图副瓣的不确定度大小。该研究为近场天线测量技术的误差分析和补偿提供了一定的理论依据。

一种新型宽频带多频微带天线设计

目前，同时适用于蓝牙、射频识别、全球微波无线互联网和无线局域网这几大主流物联网通信技术标准的多频天线设计较少，为此，提出了一种新的小型化宽频带多频微带天线。该微带天线主要由一个矩形环、一个开口六边形环、三条矩形带以及缺陷地组成，可同时工作在蓝牙、射频识别、全球微波无线互联网和无线局域网的通信频段上。天线谐振频率分别为2．47GHz、3．48GHz和5．55GHz，相应带宽为0．11GHz（2．38～2．49GHz）、0．86GHz（3．19～4．05GHz）和1．11GHz（4．95～6．06GHz），增益最高达到5．75dBi。实测结果显示，该天线在工作频段具有很好的辐射特性和增益．适用于当前应用的无线通信系统。

一种用于GIS局部放电检测的新型特高频传感器

研制了一种用于GIS局部放电检测的宽带特高频外部传感器,其有效带宽为300～3000MHz。用天线理论对该传感器的特性加以分析,并在实验室进行了性能实测,结果表明,该传感器有良好的特性。

紧凑型电磁带隙结构在短路微带天线中的应用

该文提出一种带有紧凑型电磁带隙结构的短路微带天线,并与相同尺寸的普通短路微带天线作比较。测试结果表明该电磁带隙结构天线在增益上增加了3dB,H面的交叉极化有了明显的改善。同时也证明了设计具有同样谐振频率的电磁带隙结构单元,使用这种紧凑型结构的单元边长尺寸仅为普通结构的50?60%左右。这对最终实现电磁带隙结构微带相控阵天线具有重要意义。

印刷偶极子天线实现全向辐射的一种设计方法

印刷偶极子天线由于具有体积小、频带宽等优点而被广泛用于许多领域。针对在某些场合需要E面全向辐射天线,设计了一个平面结构的宽带阵列天线,并利用电磁仿真软件HFSS进行仿真。天线采用了巴伦馈电的印刷偶极子作为基本单元,通过引入平面喇叭和反射单元来改善方向图不圆度,使其能在E面实现全向辐射。结果表明,它在3.5～6.5GHz的宽频率范围内的回波损耗基本在-10dB以下,E面方向图不圆度小于3dB,仿真与实测结果能够较好地吻合。

弹载天线载体截短对天线辐射特性的影响

应用几何绕射理论 ( GTD)对弹载口径天线载体截短对子午面辐射特性的影响进行了分析计算。截断模型包括弹体尾部圆柱部分、尖端锥体部分以及同时截短尾部圆柱部分和截断尖端锥体部分。计算结果表明 ,将弹体适当截短对弹载天线子午面内辐射特性影响很小 ,完全可以在弹载天线的测量中对弹体进行截短处理。

紧缩平面场扫描架系统研制

紧缩平面场 (CATR)是在较小的微波暗室里模拟远场的电磁环境 ,以行进各种天线的测量和研究 .其最终性能指标要由紧缩平面场扫描架评定 .根据紧缩平面场扫描测量原理 ,及其对扫描架平面度、直线度、定位精度及自动化程度的要求 ,研制了极坐标型紧缩场扫描架系统 ,通过采用高精度直线导轨、平面度微调方式和基于工业控制计算机的数字控制技术 ,达到了所要求的检测精度 ,满足了紧缩平面场扫描测量的要求 .