Dual-Channel Communication of Column Plasma Antenna Excited by a Surface Wave——Actualization and Simulation of Radiation Pattern

Along with the introduction of the concept of dual-channel communication,we utilized the finite-difference time-domain（FDTD） method to simulate and measure the radiation pattern under certain plasma densities and plasma collision frequencies.Results show that under certain settings,the radiation pattern of a plasma antenna resembles that of a metallic antenna.In contrast to a metallic antenna,a plasma antenna possesses other functionalities,such as dynamic reconfiguration and digital controllability.The data from simulation are similar to the measurement results,indicating that column plasma antenna can realize dual-channel communication.This work confirms the viability of realizing dual-channel communication by column plasma antenna,which adds a new but promising method for modern intelligent communication.

Reconfigurable Pattern Patch Antenna for Mid-Band 5G:A Review

New requirements in communication technologies make it imperative to rehash conventional features such as reconfigurable antennas to adapt with the future adaptability advancements.This paper presents a comprehensive review of reconfigurable antennas,specifically in terms of radiation patterns for adaptation in the upcoming Fifth Generation(5G)New Radio frequency bands.They represent the key of antenna technology for materializing a high rate transmission,increased spectral and energy efficiency,reduced interference,and improved the beam steering and beam shaping,thereby land a great promise for planar antennas to boost the mid-band 5G.This review begins with an overview of the underlying principals in reconfiguring radiation patterns,followed by the presentations of the implemented innovative antenna topologies to suit particular advanced features.The various adaptation techniques of radiation pattern reconfigurable planar antennas and the understanding of its antenna design approaches has been investigated for its radiation pattern enhancement.A variety of design configurations have also been critically studied for their compatibilities to be operated in the midband communication systems.The review provides new insights on pattern reconfigurable antenna where such antennas are categorized as beam steering antenna and beamshaping antennas where the operation modes and purposes are clearly investigated.The review also revealed that for mid-band 5G communication,the commonly used electronic switching such as PIN diodes have sufficient isolation loss to provide the required beam performance.

Antenna Array Pattern Synthesis via Coordinate Descent Method

This paper presents an array pattern synthesis algorithm for arbitrary arrays based on coordinate descent method (CDM). With this algorithm, the complex element weights are found to minimize a weighted L2 norm of the difference between desired and achieved pattern. Compared with traditional optimization techniques, CDM is easy to implement and efficient to reach the optimum solutions. Main advantage is the flexibility. CDM is suitable for linear and planar array with arbitrary array elements on arbitrary positions. With this method, we can configure arbitrary beam pattern, which gives it the ability to solve variety of beam forming problem, e.g. focused beam, shaped beam, nulls at arbitrary direction and with arbitrary beam width. CDM is applicable for phase-only and amplitude-only arrays as well, and furthermore, it is a suitable method to treat the problem of array with element failures.

Achieving Directionality and Transmit Diversity via Integrating Beam Pattern Scanning (BPS) Antenna Arrays and OFDM

In this paper, we introduce a novel merger of antenna arrays with scanning beam patterns, and Orthogonal Frequency Division Multiplexing (OFDM) systems. Controlled time varying phase shifts are applied to the antenna array elements mounted at the base station with beam patterns directed toward the desired user. This creates a small beam pattern movement called Beam Pattern Scanning (BPS). In rich scattering environments BPS creates a time varying environment leading to time diversity exploitable at the receiver enhances its probability-of-error performance. Here, we apply OFDM signals to BPS antenna arrays, and we achieve: (1) directionality, which supports Space Division Multiple Access (SDMA);and (2) a time diversity gain, which leads to high performance. We discuss the structure of the base station antenna array and the OFDM receiver that exploits time diversity. We also introduce the merger of BPS and multi-carrier OFDM (MC-OFDM) systems. In MC-OFDM each bit is transmitted over all sub-carriers after serial to parallel conversion. BPS/ MC-OFDM receiver exploits both time diversity inherent in BPS, and frequency diversity inherent in MC-OFDM transmission technique. Simulation results show high Probability-of-error performance is achie- vable via BPS/OFDM and BPS/MC-OFDM schemes comparing to the traditional OFDM and MC-OFDM, respectively. Simulations also reveal that MC-OFDM system as well as its merger with BPS is capable of mitigating large Peak-to-Average Ratio (PAPR) problem in traditional OFDM system. In addition, performance simulations with coded OFDM (COFDM) and coded MC-OFDM (MC-COFDM) and their merger with BPS are studied.

Optimal Design of Wireless Power Transmission Systems Using Antenna Arrays

Three design methods for wireless power transmission(WPT)systems using antenna arrays have been investigated.The three methods,corresponding to three common application scenarios of WPT systems,are based on the method of maximum power transmission efficiency(MMPTE)between two antenna arrays.They are unconstrained MMPTE,weighted MMPTE,and constrained MMPTE.To demonstrate the optimal design process with the three methods,a WPT system operating at 2.45 GHz is designed,simulated,and fabricated,in which the transmitting(Tx)array,consisting of 36 microstrip patch elements,is configured as a square and the receiving(Rx)array,consisting of 5 patch elements,is configured as an L shape.The power transmission efficiency(PTE)is then maximized for the three application scenarios,which yields the maximum possible PTEs and the optimized distributions of excitations for both Tx and Rx arrays.The feeding networks are then built based on the optimized distributions of excitations.Simulations and experiments reveal that the unconstrained MMPTE,which corresponds to the application scenario where no radiation pattern shaping is involved,yields the highest PTE.The next highest PTE belongs to the weighted MMPTE,where the power levels at all the receiving elements are imposed to be equal.The constrained MMPTE has the lowest PTE,corresponding to the scenario in which the radiated power pattern is assumed to be flat along with the Rx array.

Pattern synthesis optimization of 3-D ODAR based on improved GA using LSFE method

Pattern synthesis in 3-D opportunistic digital array radar(ODAR) becomes complex when a multitude of antennas are considered to be randomly distributed in a three dimensional space.In order to obtain an optimal pattern,several freedoms must be constrained.A new pattern synthesis approach based on the improved genetic algorithm(GA) using the least square fitness estimation(LSFE) method is proposed.Parameters optimized by this method include antenna locations,stimulus states and phase weights.The new algorithm demonstrates that the fitness variation tendency of GA can be effectively predicted after several "eras" by the LSFE method.It is shown that by comparing the variation of LSFE curve slope,the GA operator can be adaptively modified to avoid premature convergence of the algorithm.The validity of the algorithm is verified using computer implementation.

Analysis of the radiation Resistance and Gain of Full-Wave Dipole Antenna for Different Feeding Design

This paper demonstrates the analysis of antenna pattern and gain for different designs of full-wave dipole antenna feeding techniques. Seven such techniques were studied and analyzed;symmetrical dual feeding in phase, symmetrical dual feeding out of phase, asymmetrical dual feeding in phase, asymmetrical dual feeding out of phase, symmetrical triple feeding in phase and symmetrical triple feeding out of phase. Symmetrical dual feeding in phase produced high gain as compared to the single and center-fed antennas. An improvement of about 3 to 3.5 dB was achieved comparing to center tap fed and off center fed. It was found that an asymmetrical dual feeding in-phase provides good performance, considering the directivity, pattern, and input impedance. A 2.46 dB gain has been attained. It was found that a symmetrical triple feeding provides an overall best performance with respect to gain, radiation pattern, beam width and input impedance.

Researches on Reconfigurable Antenna in CEMLAB at UESTC

This paper summarizes the achievement and progress in the research on reconfigurable antenna since 2001, in Computational Electromagnetics Laboratory （CEMLAB） at University of Electronic Science and Technology of China （UESTC）. Several typical reconfigurable antennas are introduced, which can realize frequency, pattern or frequency-pattern reconfigurability by electrically controlling methods. Some techniques involved in the design and analysis of reconfigurable antennas are reported. At last, the development trend of reconfigurable antenna is predicted in the conclusions.

Mathematical Simulating Model of Phased-Array Antenna in Multifunction Array Radar

A mathematical simulating model of phased-array antenna in multifunction array radar has been approached in this paper, including the mathematical simulating model of plane phased-array pattern, the mathematical simulating model of directionality factor, the mathematical simulating model of array factor, the mathematical simulating model of array element factor and the mathematical simulating model of beam steering.

Effect of Metal and Magnetic Slab on Radiation Characteristics of Monopole Antenna

The effect of metal and magnetic slab on the radiation characteristic of monopole antenna is studied in this paper. The presence of metal slab changes the antenna radiation pattern and it also increases the gain up to 4.6 dB. The radiation characteristic of monopole antenna is determined by the separation distance between planar monopole and metal slab. In addition, magnetic slab also changes the antenna radiation pattern and it also increases the gain up to 3 dB. Metal slab makes antenna generate reflection, but magnetic slab makes antenna generate refraction is their difference. As to the application slab, the initial pattern of the antenna without materials was omnidirectional. However, when the materials were added, its pattern would change, making the antenna to have other usages and transition effect. They will influence electromagnetic in power systems.

A Compact UWB MIMO Antenna for Portable Applications

A novel compact multiple-input-multiple-output (MIMO) antenna for portable ul-trawideband (UWB) applications is presented. This antenna consists of two modified planar-monopole antenna elements with coplanar waveguides-fed printed on one side of the substrate. To enhance isolation and increase impedance bandwidth, a tree like stubs is placed on the ground plane at the 45°axis. The measured results show that the MIMO antenna operates from 2.3 GHz to 13 GHz, covering WLAN, WiMAX, and UWB. The low mutual coupling and low envelope correlation coefficient of less than 0.2 across the whole frequency band proved that this antenna was suitable for MIMO/diversity systems. Also, good performance of radiation patterns and the antenna’s compact size make it a good candidate for portable devices.

Space-borne antenna adaptive anti-jamming method based on gradient-genetic algorithm

A novel space-borne antenna adaptive anti-jamming method based on the genetic algorithm （GA）, which is combined with gradient-like reproduction operators is presented, to search for the best weight for pattern synthesis in radio frequency （RF）. Combined, the GA＇s the capability of the whole searching is, but not limited by selection of the initial parameter, with the gradient algorithm＇s advantage of fast searching. The proposed method requires a smaller sized initial population and lower computational complexity. Therefore, it is flexible to implement this method in the real-time systems. By using the proposed algorithm, the designer can efficiently control both main-lobe shaping and side-lobe level. Simulation results based on the spot survey data show that the algorithm proposed is efficient and feasible.

Beam Pattern Scanning (BPS) versus Space-Time Block Coding (STBC) and Space-Time Trellis Coding (STTC)

In this paper, Beam Pattern Scanning (BPS), a transmit diversity technique, is compared with two well known transmit diversity techniques, space-time block coding (STBC) and space-time trellis coding (STTC). In BPS (also called beam pattern oscillation), controlled time varying weight vectors are applied to the antenna array elements mounted at the base station (BS). This creates a small movement in the antenna array pattern directed toward the desired user. In rich scattering environments, this small beam pattern movement creates an artificial fast fading channel. The receiver is designed to exploit time diversity benefits of the fast fading channel. Via the application of simple combining techniques, BPS improves the probability-of-error performance and network capacity with minimal cost and complexity. In this work, to highlight the potential of the BPS, we compare BPS and Space-Time Coding (i.e., STBC and STTC) schemes. The comparisons are in terms of their complexity, system physical dimension, network capacity, probability-of-error performance, and spectrum efficiency. It is shown that BPS leads to higher network capacity and performance with a smaller antenna dimension and complexity with minimal loss in spectrum efficiency. This identifies BPS as a promising scheme for future wireless communications with smart antennas.

Comparative Study of the Performances of Opaque and Transparent Patch Antennas

The performances of two microstrip patch antennas with low visual impact are presented in this paper and compared to an opaque solution. These consist in a copper film deposited on a Borofloat 33 glass substrate through a thin titanium gripping layer. The mesh is obtained by wet chemical etching. Antennas differ by the dimensions in the ground plane mesh pattern. The opaque antenna only consists of a full copper deposit. The transparency work was mainly carried out on the ground plane as it is the largest area available. Specific attention is paid to optical transparency in the visible light spectrum, sheet resistance and electromagnetic performances in the [2.8;3 GHz] bandwidth. They are measured in each case, compared and discussed. Both simulations and measurement results show good performance, especially the antenna with the most transparent ground plane: a high level of optical transparency of almost 73%, coupled with a sheet resistance of less than 0.028 Ohms/sq and a gain of about 3.22 dBi at 2.8 GHz, slightly higher than the gain of the reference opaque antenna of about 2.66 dBi at 2.99 GHz. The opaque reference antenna has a bandwidth of 1.30 GHz while those of the transparent antennas are about 1.60 GHz and 2.10 GHz (S11 < −10 dB). This solution presents a real interest for low cost integrated and discrete antenna solutions in ISM band.

Design of Ellipse Antenna Array for Cellular Phone Localization Systems

This paper describes our contribution in the ANR (Agence Nationale de la Recherche) project called GELOCOM (GEo-LOCalisation de telephOnes Mobiles) managed by the THALES Communications company, dedicated to the emergency localization of cellular phones. This contribution takes place in the field of antennas, with the development of broad-band systems: a circular array of six elements with separated outputs for the receiving part. In this paper, we present the design and the characterization of broad-band double ellipse array antenna. This special structure is chosen in order to obtain a good omnidirectional radiation pattern, enhance the gain and maximize the V/H polarization ratio. In comparison with the already existing antenna systems in the wireless market for similar purposes, the proposed antenna has considerably shown better performance which makes it competitive among other antenna models. For the design and optimization of antennas, we use CST MWS software. The antennas have been designed and successfully measured.

Multi-Band Antenna with Three Folded Monopoles for Mobile Communication Systems

This paper presents the design and the experimental characterization of a new multi-band antenna consisting of three folded monopoles dedicated to mobile communication systems. The originality of this paper is to get the PMR (Professional or Private Mobile Radio) band with the GSM (Global System for Mobile Communications), DCS (Digital Cellular System) and UMTS (Universal Mobile Telecommunications System) bands. The main lobe of the antenna radiates in the zenith direction with a linear polarization over all bands. It is interesting to design the proposed antenna in order to obtain better performances in terms of directive radiation pattern (especially in the PMR band) in comparison with the already existing antenna systems in the wireless market for similar purposes. The prototype was studied with the software CST-MWS (Micro wave studio 2012). The antenna has been designed and successfully measured.

一种等通量波束的多极化可重构天线

随着航天技术的革新,对近地轨道的通信需求逐年增高。近地轨道卫星就在此背景下产生,主要应用于遥感探测天气预报和数据通信领域。由于近地轨道卫星天线辐射波束所覆盖的地球表面是球面,因此波束通常设计为等通量形式。由于卫星通信通常存在极化失配、多径效应等问题,选择多极化而不是圆极化作为近地卫星天线的工作状态能更好地适应复杂的工作环境,保证通信质量,将等通量波束天线和多极化可重构技术结合起来有很大的应用前景。基于一对正交圆极化波能合成线极化波的设计原理,文中提出了一种具有等通量波束的多极化可重构天线,该天线由可重构馈电网络和带扼流环的隔片极化器圆波导组成。馈电网络中嵌入单刀四掷开关(SP4T)与单刀双掷开关(SP2T),通过改变开关的工作状态,馈电网络将给圆波导提供不同的馈电条件,在圆波导内隔片的作用下天线实现两种圆极化与两种线极化的可重构。通过在圆波导口引入扼流环以及波导口作“T”型开槽处理,实现波束赋形,并且保证天线在不同极化状态下辐射等通量波束。实测结果显示,天线在不同的极化状态下-15 dB重叠阻抗带宽14.7%,覆盖4.80~5.56 GHz,方向图顶部在θ为-24°~+24°范围内具有平坦效果,圆极化状态下空间轴比覆盖-51°~+50°,覆盖范围大于方向图顶部平坦范围。天线实测结果与仿真结果有较好的一致性,具有多极化和方向图顶部平坦的优势,可满足移动通信和卫星通信中多极化应用场景的需要。

A Compact Diversity Antenna for Handheld Terminals

The handheld terminals antenna should have a small size, sufficient gain and big bandwidth. In this paper, a compact planar inverted-L diversity antenna for handheld terminals is proposed. Three diversity antennas operating at 2.15 GHz are designed and the effect of important parameters of the proposed antenna is measured. The isolation is found to be better than 13 dB, the usable bandwidth is about 13%. Moreover, the measured radiation patterns are also obtained that the backward radiation is decreased.

数模混合二维相控阵雷达远场收发校准方法研究

本文提出了一种基于最小系统设计准则的数模混合二维相控阵雷达远场收发校准方法,给出了实现流程、数据分析过程和实测结果。方向图的实测结果显示本文提出的校准方法得到的收发方向图主要技术指标良好且均满足使用要求,在实际工程中具有较好的操作性和推广性。