Ansoft HFSS仿真分析半波对称振子天线波长缩短效应

利用电磁仿真软件Ansoft HFSS,在5G信号n79波段内,取中心频率分别为4.2,4.4,4.6,4.7,4.8和5.0GHz进行仿真分析,得出这些频率的信号在实际天线中波长分别为64.04,61.22,59,96,58.7, 56.22,67.04 mm。表明,在实际天线中这些信号对应的波长与自由空间波长波长相比缩短率为6.1%。将此结果应用到信号频率分别为5和28GHz的天线仿真设计中,可计算出该频率信号在天线中的实际工作波长分别为117.4和10.06 mm。仿真结果表明,所得天线的谐振频率与预期吻合;天线的回波损耗,相对带宽,输出阻抗和方向增益皆满足移动基站通信天线的要求。     

双频共面波导天线设计

本文提出了一种基于共面波导结构的工作频率在2.45GHz和5.8GHz的双频带天线的设计。该天线采用了增加突出结构和边缘开槽的方法,通过时域有限差分法(FDTD)对共面波导尺寸的变化进行了仿真与优化,得出了共面波导结构对天线性能的影响,从而给出了相应的结构尺寸。并实际测量了天线的反射参数以及方向图,对比测量结果与仿真结果基本符合。最后本文对本次天线设计做出总结并对测量结果做了误差分析。     

基于神经模糊技术的漏钢诊断预报模型的研究

剖析了连铸结晶器粘结性漏钢的基本特征,利用热电偶,提出一种的漏钢诊断预报模型。主要包括神经模糊判别技术,单偶神经网络判别技术,组偶神经网络判别技术,并用现场工艺数据进行了仿真。     

基于曲率值追踪的气象槽线自动分析算法

针对传统槽线自动分析算法中存在的处理效率较低，且分析准确度不高的问题，提出一种基于曲率值追踪的槽线自动分析算法。算法利用位势高度场格点数据，直接计算格点处曲率值，并根据曲率值及相对位置对格点进行分类判别，以提取候选槽点；在候选槽点中筛选合理槽点进行追踪连接；最终通过后处理步骤，得到槽线自动分析结果。实验结果表明，该算法可有效实现气象槽线的自动分析，在分析准确度和运行速度方面较之前算法均有所改进。     

基于方向场的计量刻度线倾斜校正

为了克服牛奶瓶刻度的倾斜给字符分割与识别带来不便的问题,本文提出了一种基于方向场的计量刻度倾斜校正方法。该方法利用刻度线的特征,利用sobel算子计算梯度方向场,进而求出水平倾斜角度和垂直倾斜角度,然后按所得夹角再加上双线性插值进行旋转校正。实验证明,这种方法具有较强的可行性和有效性。     

基于多天线GPS的船载卫星天线跟踪系统

为了克服传统的船载卫星天线跟踪系统因采用多种传感器带来的硬件成本高、软件接口复杂、系统运行速度慢和精度低等问题,提出了用多天线GPS姿态测量的方法,将GPS天线直接安装在卫星接收天线上,根据GPS各个天线的三维位置信息数据计算船载卫星天线的姿态,再由卫星的位置计算天线相对于卫星的角度并进行跟踪,实现了用一种传感器完成船载天线跟踪系统的姿态测量与控制。系统在内湖和海上进行多次测试,测试结果表明:在船体航行过程中电视信号的强度保持在60%~70%之间,对亚洲2号卫星进行移动跟踪的方位角误差的测试数据在±1.5°之间。该设计具有测试方法简单、误差小、成本低和使用方便等特点,有广泛的市场前景。     

一种基于物联网的多天线RFID纱锭定位系统

针对纺纱厂需要对大量纱锭筒管的位置信息采集的需求,在纱厂引入RFID技术。典型的RFID阅读器只有一根天线,一次只能读一个电子标签。为了实现一个RFID阅读器一个工作周期能够读取多个电子标签,设计了一种多天线RFID阅读器。描述了此种多天线RFID阅读器的硬件组成与软件构成,同时对多天线RFID阅读器的线圈数目、阅读距离与切换时间之间的关系进行了探索。为解决RFID系统对数据传输的需求,根据中间件思想构建了基于Web Services技术的接口,介绍了其具体实现的模型,为企业内部间、不同企业之间的信息提供了一个松耦合的系统集成方案。     

基于广义势场的三维形体多层次线骨架构建

在Cornea建立的基于广义势场的骨架生成算法的基础上,提出一种新的多层次线骨架构建算法。通过选取不同的r值简化边界点,减少了斥力场的计算时间。与Cornea算法不同,选取曲面变分替代曲率,并选取局部曲面变分值较高的边界点作为种子点生成多层次的骨架。由于曲面变分比曲率更适用于反映点云形体表面的性质且计算速度较快,因此该算法更适于处理点云,且具有一定的鲁棒性。同时分析了不同的r值与骨架连通性和计算时间的关系。实验结果表明,经边界点简化处理,斥力场计算时间比原来减少一半左右,且以此生成的骨架能够保持较好的光滑性和连通性。还尝试了另一种基于曲面变分简化边界点的准则,并仔细考查了高曲面变分点、邻域半径k以及不同的空间划分尺度n对多层次骨架生成的影响。     

基于多天线NOMA的通信系统高能效功率分配方法

文中提出一种基于多天线非正交多址接入的通信系统高能效功率分配方法.在该方法中,基站采用非正交的方式接入用户,将用户分为多个簇,利用迫零接收方法处理簇间的用户干扰,同时采用串行干扰消除方法处理簇内的用户信号.为了提升该系统的能量效率性能,对基站发射功率的分配方案进行了优化.文中建模该功率分配问题为一个分数形式的非凸优化问...     

High‐gain waveguide slot antenna using simple parasitic patch's cover

In this article, a way based on using miniature patch cells has been proposed to increase gain and bandwidth of the waveguide slot antenna. In the presented approach, an array of 3 × 3 metal patches has been used as superstrate to create Fabry Perot theorem resonance cavity. The proposed high ‐ gain and simple antenna is composed of a conventional waveguide slot antenna with an extended broad wall, and an array of parasitic patches which are symmetrically placed over slot at a distance of about free ‐ space half wavelength. The slot has been created on a rectangular waveguide WR90 with 22.86 mm × 10.16 mm × 52.5 mm dimension, also extended wall dimension is 2λ₀ (67.5 mm) × 3λ₀ (107 mm). It has been shown that the proposed structure compared with the conventional waveguide slot antenna improves antenna peak gain from 6.5 to 16.5 dBi and, in the same time, antenna bandwidth from 11% to around 16.2%. More important advantage of the proposed antenna is that unlike to other Fabry Perot antenna with the same gain, there is not any dielectric material in the proposed structure. A prototype antenna was simulated, fabricated, and measured for verification.     

Two-dimensional broadband and wide angle scanning multi-beam antenna based on leaky-wave metasurface

In this article, a novel two-dimensional multi-beam antenna with a broad band and a wide angle scanning range is proposed. It is composed a leaky-wave metasurface (MTS) and a four-port feeding network with high isolation. The leaky-wave MTS formed by T-shaped slots is displayed as radiator and divided into four angular sectors, each one devoted to the formation of a beam in a given elevation plane. At every fixed frequency, the antenna can radiate multi beam in azimuth plane through exciting different ports. Also, multi-beam radiation with a broad band and a wide angle scanning range in the elevation plane is realized when fixed port is excited at different frequency. The antenna with overall size of 207 mm by 207 mm by 2.0 mm is fabricated on FR-4 substrate. The measured and simulated results show that the ?10 dB relative bandwidth is 30% (from 9.44 to 12.77 GHz). When different ports are excited at the same frequency, the azimuth of radiation beam is steered to 0°, 90°, 180°, and 270°. In addition, the beam-scanning range of the prototyped antenna is from 29° to 75° when the frequency sweeps in the range of 9.5–12.0 GHz. Also, the maximum radiation efficiency reaches to 31.1% and the measured peak gain within the scanning range is 12.29 dBi.     

A compact substrate‐integrated‐waveguide monopulse slot antenna array with TE20 mode

A compact substrate‐integrated‐waveguide (SIW) monopulse slot antenna array with T_E20 mode is proposed, manufactured, and tested in this communication. The TE₂₀ mode electric field distribution is used in this antenna design. The phase difference required by the monopulse system is constructed by changing the orientation of the end of the top microstrip feed line. The microstrip line implements not only the feed function, but also the function of a monopulse comparator. The design greatly reduces the size of the monopulse comparator and the feed network, and improves the aperture efficiency of the antenna. Our measurement shows that the operating frequency of the antenna is 10.4 GHz, and the maximum gain of the sum beam is 13.7 dBi, and the difference beam null depth is ?26 dB. The antenna has the advantages of simple structure, small size, and easy integration of planar circuits. This proposed idea can open new ways for monopulse antenna design.     

Computer aided equivalent circuit model of SIW cavity backed triple band slot antenna

In this article, a study of planar triple band unidirectional Substrate Integrated Waveguide (SIW) cavity backed slot antenna using equivalent circuit model is presented. The proposed antenna uses a modified dumbbell shaped slot of much larger length placed in a planar SIW cavity to excite three closely spaced SIW cavity hybrid modes which help the slot to radiate into free space. The design is analyzed with the help of equivalent circuit model to predict the resonant frequencies of the design and also to explain the excitation mechanism of the proposed slot antenna. The proposed circuit model is validated by comparing its performance with the simulation model for a wide range of parametric variation. The relationship between modification in design dimension with the variation of coupling between feed line and cavity modes is studied which gives a design guideline for the proposed antenna. The fabricated prototype of the antenna resonates at 7.39, 9.43, and 14.79 GHz with a gain of 3.2, 4.9, 4.7 dBi and front‐to‐back ratio (FTBR) of 10 dB, respectively, at three resonant frequencies which makes it suitable for C (4–8 GHz), X (8–12 GHz), and Ku (12–18 GHz) band applications.     

Computer-aided design of a CPW-fed slot antenna for MM-wave applications

This article presents a comprehensive parametric study with experimental characterization of an inductively coupled CPW-fed slot antenna on a GaAs substrate for MMIC applications. The length, width, and feed inset of the antenna are varied and their influences on the input impedance, bandwidth, and gain are investigated. The parametric study reveals that the slot length is the prime factor for determining the resonant frequency, while the width is used for fine-tuning of resonant frequency and gain-bandwidth product. For the fixed slot dimensions, the feed inset tremendously affects both resonant frequency and input match. The manufactured antenna resonates at 22.4 GHz with a 6.1% impedance bandwidth, 2% gain bandwidth, 2.5-dBi boresight gain, and 5-dB front-to-back (F/B) radiation level. The antenna exhibits bidirectional radiation patterns with almost omnidirectional patterns in the E-plane and a wide beamwidth of 84° 3-dB beam width in the H-plane. © 2003 Wiley Periodicals, Inc. Int J RF and Microwave CAE 14, 4–14, 2004     

A cavity‐backed quad‐slot antenna with novel aperture‐coupled feed for circular polarization

This article describes a novel aperture‐coupled feed, for the excitation of a cavity‐backed quad‐slot antenna with circular polarization. Firstly, a quad‐slot cavity‐backed antenna with linear polarization (LP) is proposed. Then, a novel aperture‐coupled feed, which is composed of a cross‐shaped coupling aperture and a T‐shaped feeding microstrip line, will be applied to this LP antenna. By differing the lengths of the four radiation slots together with the novel aperture‐coupled feed, 90° phase difference and equal magnitude between the radiations from the two pairs of slots can be generated. As a result, a good performance of axial ratio will be achieved for the proposed antenna. A prototype is fabricated at Ka band for a demonstration. Investigations show that the antenna can present a minimum axial ratio (AR) of only about 0.37 dB, as well as a fractional AR bandwidth of about 0.94%. A relative high gain of 6.9 dBic at 32.1 GHz is also achieved for the prototype. The proposed substrate integrated cavity backed antenna with circularly polarization has great potential to be integrated into millimeter‐wave transceiver modules. © 2016 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:588–594, 2016.     

Compact CPW‐Fed slot antenna with harmonic suppression

A compact coplanar waveguide (CPW)‐fed uniplanar antenna with harmonic suppression characteristics is presented. The above characteristics are achieved by properly modifying the ground plane and adjusting the signal strip of an open‐ended CPW‐fed transmission line. The simulated and experimental characteristics of the antenna are presented, compared, and discussed. © 2011 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2011.     

Substrate integrated waveguide based cavity‐backed self‐triplexing slot antenna for X‐Ku band applications

A planar substrate integrated waveguide (SIW) based cavity‐backed self‐triplexing slot antenna is proposed for X‐Ku band applications. The antenna comprises of the SIW cavity, radiating slots, and feeding networks. The radiating slots; that are etched on the upper metallic plane of the SIW, are backed up by the three radiated quarter cavities (QCs). The radiating slots in the respective QCs are of different lengths, excited by three separated orthogonal feed lines to resonate at three different frequencies as 11.01, 12.15, and 13.1 GHz. By fine‐tuning the antenna parameters, an intrinsic input port isolation of better than 26 dB is realized which helps in achieving the self‐triplexing property. The behaviors of individual cavity modes at three resonant frequencies are explained with the help of Z‐parameter. The proposed antenna layout is easy to integrate with the planar circuit. The proposed antenna is fabricated and measured results display a close concern with the simulated results. Moreover, a unidirectional radiation pattern and gain of 5.1, 5.54, and 6.12 dBi at resonant frequencies are realized.     

Untilted slot array antenna at the narrow wall of the waveguide using double‐ridge

In this article a novel array antenna composed of untilted slots in the narrow wall of the double‐ridge waveguide, with significantly improved cross‐polarization, is presented. In the first step, suitable radiating elements for designing a linear slot array antenna were created. An untilted slot which is created the narrow wall of the double‐ridge waveguide is suggested to be used as the radiating resonance slot. The concave and convex ridges are located under the untilted slots only. It is shown that the concave and convex double ridge waveguides can produce an orthogonal current distribution in the place of the slots. They are also placed successively to produce the required phase inversion between adjacent slots. The linear array consists of nine uniform resonant untilted slots in the double ridge waveguide and is designed at the frequency of 5 GHz using the normalized conductance of each radiating slot. Analyzing the simulation results shows that cross‐polarization of the designed array was significantly improved, it was also found that the cross‐polarization and the SLL were respectively about ?65 and ?16 dB. © 2010 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2010.     

Design of a compact orthogonal fed self‐diplexing bowtie‐ring slot antenna based on substrate integrated waveguide

In this article, a novel design of compact cavity‐backed slot antenna based on substrate integrated waveguide (SIW) technology is presented for dual‐frequency communication services. A single layer printed circuit board is applied to implement the proposed antenna. The bowtie‐ring slot engraved on the SIW square cavity is excited using two orthogonal microstrip feed lines to operate at two distinct frequencies (6.62 GHz and 11.18 GHz). The proposed antenna allows each of these frequencies to be designed independently. A prototype of the proposed cavity‐backed antenna that radiates at both 6.62 GHz and 11.18 GHz is fabricated and measured. The port isolation better than 29.3 dB is achieved by utilizing the transmission zeros (TZs), which are produced due to the orthogonal feed lines, TE₁₁₀ mode and coupling between the TE₁₂₀ and TE₂₁₀ modes. The measured peak gains of the proposed diplexing antenna are 5.77 dBi and 5.81 dBi at lower and upper resonating frequencies, respectively. The proposed dual‐frequency antenna exhibits the front‐to‐back‐ratio (FTBR) and cross‐polarization level greater than 26 dB and 21 dB, respectively, at both resonating frequencies.