一种新型共边矩形环嵌套的分形多频天线设计

提出了一种新型分形结构的天线,该分形结构由多个共用一条边的矩形环嵌套构成。由于结构的自相似特性,使天线能够在多个频段工作。研究表明,天线的通频带个数由分形结构的矩形环个数控制,且各谐振频点与相应辐射单元的尺寸密切相关。设计了能同时工作在蓝牙、WLAN和WiMAX频段的三频天线,天线仿真的谐振频点分别为2.44GHz、3.55GHz和5.59GHz,相应的带宽分别为7.0%(2.35GHz-2.52GHz)、15.0%(3.28GHz-3.81GHz)和30.1%(5.13GHz-6.95GHz)。实物的测试结果与仿真结果基本吻合,符合设计要求。     

短路针加载三角形微带贴片天线的研究

短路针加载微带贴片天线具有较低的谐振频率,特别适用于低频便携式通信设备(如手机)中.与短路针加载矩形和圆形贴片天线相比,短路针加载三角形贴片天线具有更低的谐振频率.本文基于腔模理论,利用未加载三角形贴片天线的静态模,提出了短路针加载三角形贴片天线的理论分析方法,给出了天线谐振频率、输入阻抗及反射损耗的计算公式.数值计算与实测结果相吻合,表明这种分析方法是有效的.     

Analysis of gap-coupled microstrip antenna

In the present paper the analysis of a gap-coupled microstrip antenna (GCMSA) is carried out using the circuit concept and consequently various parameters such as input impedance, VSWR and return-loss are investigated for different air gap lengths. It is observed that the resonant frequency of the antenna with different substrates depends on the gap length. The gap-coupled antenna behaves as an RL network below the resonant frequency for all substrate materials and gap lengths, whereas the antenna behaviour above resonance is like an RC network. It is further observed that the resonant frequency of the GCMSA decreases with increasing gap length.     

顶部加载单极天线的研究与仿真

短波天线的尺寸是其应用的主要障碍。论文分析了顶部加载对天线性能的影响,选取顶部加载单极天线作为研究和仿真的对象。通过改变顶线个数、张角、长度以及直径等参数值,仿真分析各参数变化对天线性能的影响。结果表明,顶部加载可以有效降低天线的谐振频率,实现天线的小型化。     

Approximate expression for the resonant frequency of a rectangular patch antenna

An approximate expression is derived for the resonant frequency of a rectangular patch antenna. It shows explicitly the dependence of the resonant frequency on the characteristic parameters of the antenna. Accuracy of the expression is established by comparing the theoretical results with available measured results.     

Design and Analysis of Triple-Band Rectangular Microstrip Antenna Loaded with Notches and Slots for Wireless Applications

In this paper, a rectangular triple-band microstrip antenna has been designed for Bluetooth application by successively loading notches and slots of different dimension in radiating patch. The conventional microstrip antenna suffers with narrow impedance bandwidth. The current work affords an alternate option to enhance the bandwidth of antenna that resonates in triple-band operation. Initially, the antenna is resonating in single-band but after loading slots, the bandwidth of microstrip antenna has been obtained 1.97% (lower band), 10.35% (middle band) and 33.16% (upper band) resonating in triple-band with three resonant frequency at 1.422 GHz (lower resonant frequency), 1.791 GHz (middle resonant frequency) and 2.467 GHz (higher resonant frequency). The suggested antenna has upper frequency band in the range of 2.045–2.858 GHz resonating at 2.467 GHz frequency and it is appropriate for Bluetooth applications (2.40–2.48 GHz) and both lower band useful for other wireless (L-band) applications. The return loss of upper band is ??34.52 dB at 2.467 GHz. The suggested microstrip antenna is directly fed by 50 ohm microstrip line feed. The suggested antenna has been designed, simulated and analyzed by IE3D simulation software.

     

A compact dual band planar branched monopole antenna for DCS/2.4-GHz WLAN applications

A compact dual band planar antenna for a digital communication system (DCS)/2.4-GHz WLAN application is presented. The two resonant modes of the proposed antenna are associated with various length of the monopoles, in which a longer arm contributes for the lower resonant frequency and a shorter arm for higher resonant frequency. The experimental results show that the designed antenna can provide excellent performance for DCS/2.4-GHz WLAN systems, including sufficiently wide frequency band, moderate gain, and nearly omnidirectional radiation coverage. The outcome of the experimental results along with the design criteria are presented in this letter.     

Broadband dual frequency microstrip antenna

A new dual port microstrip antenna geometry for dual frequency operation is presented. The structure consists of the intersection of two circles of the same radius with their centres displaced by a small fraction of the wavelength. This antenna provides wide impedance bandwidth and excellent isolation between its ports. The gain of the antenna is comparable to that of a standard circular microstrip antenna operating at the same resonant frequency. A theoretical analysis for calculating the resonant frequencies of the two ports is also presented     

Graphene based tunable and wideband terahertz antenna for wireless network communication

A wide band terahertz dipole-antenna using graphene with tunable resonant frequency is proposed. Presence of graphene in the antenna is shown to electrically tune resonant frequency and to push the antenna to resonate with multibands in terahertz regime. The proposed terahertz antenna shows maximum of five tuning frequencies and better performance parameters such as return loss of ?? 39.7 dB, maximum directivity of 9.3 dB, five resonant tuning frequencies (multi resonances) at chemical voltage of 0.5 eV, maximum fractional bandwidth of 15.6%, maximum radiation efficiency of 21.5% and large bandwidth of 2.32 THz. Large bandwidth of the antenna can be very useful for highest possible data transfer among wireless devices. The proposed graphene based terahertz antenna has the dimensions of few micrometers so miniaturization i.e. size is reduced to 0.007 mm² which is suitable for size limited future applications such as Wireless Networks on Chip, software defined meta material and Wireless Nano Sensor Networks (WNSNs). Size of the proposed terahertz antenna is less than that reported in the literature. One reconfigurable and miniaturized antenna may replace a number of single function radiators, thereby also cost and size of a WNSNs can be abridged while performance is improved.

     

可调频矩形帖片天线的研究

本文首次采用有限元法对有调谐销钉的可调频薄基片矩形贴片微带天线的谐振频率和输入阻抗进行了计算,谐振频率的计算结果与实验结果符合很好.该方法原则上适合于任意数目调谐销钉置于任意位置的情形.可能会是处理带调谐销钉的最有效的方法.     

低RCS栅格微带天线研究

研究了栅格微带天线在微带天线RCS减缩中的应用。分析了栅格线宽度、栅格线间距、栅格化方式等参数对天线的谐振频率、增益的影响。设计了一副具有低RCS特性的栅格微带天线,与谐振在同频率的微带贴片天线相比,天线的增益仅降低0. 6dBi,而天线在2~10GHz频带内的平均RCS降低4dBsm。     

Differential Dual‐Frequency Antenna for Wireless Communication

A novel differential dual‐frequency antenna using proximity coupling is proposed. Dual bands are realized by a slot in the ground plane. The lower resonant frequency is controlled by the slot in the ground plane, and the upper resonant frequency is mainly determined by the dimensions of the radiating patch. Measured results show that the proposed antenna can operate at 2.51 GHz and 5.38 GHz.     

Measurement and analysis of miniature multilayer patch antenna

Although the microstrip patch antenna has a number of advantages such as low-cost and light weight, its physical size is quite large at low microwave frequencies. The designs of multilayer miniature patch antennas with coaxial feed are presented. The first design is a rectangular two-layer patch antenna. Measured results and the results of a preliminary analysis are presented. The projection area of the two-layer patch antenna is kept the same as the single-layer rectangular patch antenna. The resonant frequency of the two-layer antenna is reduced by 50% and has bandwidth of 5%, which is wider than the single-layer rectangular patch antenna. In the second design, the upper patch is cut into a bow-tie shape. This results in a 60% reduction in resonant frequency and a 12% bandwidth. Both the two-layer rectangular and the two-layer bow-tie antennas have good radiation patterns, with cross-polarization level lower than the copolarization level by more than 20 dB     

Theoretical and experimental study of the input impedance of thecylindrical cavity-backed rectangular slot antennas

The authors study the input impedance of a cylindrical cavity-backed slot antenna based on mode matching and the complex Poynting theorem. Two cavity-backed slot antennas were fabricated to verify the theory. The numerical results agree very well with measurements. Two resonant frequencies were found from the input impedance. One resonant frequency is attributed to the rectangular slot and the other is due to the cavity. The slot length controls the first resonant frequency and has a much stronger effect on the input impedance at the antenna operating frequency as compared with the cavity length     

Design of reconfigurable slot antennas

In this paper the design of a compact, efficient and electronically tunable antenna is presented. A single-fed resonant slot loaded with a series of PIN diode switches constitute the fundamental structure of the antenna. The antenna tuning is realized by changing its effective electrical length, which is controlled by the bias voltages of the solid state shunt switches along the slot antenna. Although the design is based on a resonant configuration, an effective bandwidth of 1.7:1 is obtained through this tuning without requiring a reconfigurable matching network. Four resonant frequencies from 540-890 MHz are selected in this bandwidth and very good matching is achieved for all resonant frequencies. Theoretical and experimental behavior of the antenna parameters is presented and it is demonstrated that the radiation pattern, efficiency and polarization state of the antenna remain essentially unaffected by the frequency tuning     

基于Hilbert分形结构的电子标签天线设计研究

基于分形理论思路,设计了一款Hilbert分形结构的无源电子标签天线,分析研究了天线基板材料和封装材料的相对介电常数大小与介质厚度对天线性能的影响。仿真结果表明:随着介质厚度和材料相对介电常数的增加,谐振频率下降,但是对第一谐振频率点的方向图影响不大。这在电子标签的设计、仿真和制作中具有重要的参考意义。     

电流路径法在微带天线设计中的应用研究

微带贴片天线上的电流分布与它的工作模式、谐振频率有直接关系.通过分析微带天线贴片表面的电流分布来优化微带天线的结构,从而使天线性能满足要求,这种方法直观、有效,在国内外已被广泛采用.文中由规则矩形贴片的谐振频率和该贴片上的电流分布出发,探讨在保持电流路径长度不变的情况下,贴片形状的变化对谐振频率的影响,从而找到应用电流路径法设计多波段天线的更一般性的规律.     

Resonance of a rectangular microstrip patch on a uniaxial substrate

Effects of uniaxial anisotropy in the substrate on the complex resonant frequency of the microstrip patch antenna are investigated in terms of an integral equation formulation. The complex resonant frequency of the microstrip patch antenna is calculated using Galerkin's method to solve the integral equation. The sinusoidal functions that are selected as the basis functions, which show fast numerical convergence. Numerical results indicate that both the resonant frequency and the half-power bandwidth are increased due to positive uniaxial anisotropy and decreased due to negative uniaxial anisotropy     

Imaginary part of antenna's admittance from its real part usingBode's integrals

The imaginary part of an antenna input admittance is calculated from its real part using Bode's integrals. Since the real part is typically a smoother function of the frequency than the imaginary part, the procedure presented here requires computation at a smaller number of frequency points, thus saves time, and is ideal for systems whose input conductance exhibits sharp peaks. A numerical procedure to evaluate the singular Bode's integral is also presented. Numerical examples using a wire antenna are used to illustrate the advantages of this approach compared to calculations involving a densely scanned frequency range. The noise stability and robustness of the algorithm are demonstrated through the successful prediction of the susceptance and the resonant frequencies of the antenna in the presence of random noise in the conductance     

Design and Simulation of a Novel Micromachined Frequency Reconfigurable Microstrip Patch Antenna

In this paper, a novel model of a frequency reconfigurable microstrip patch antenna based on MEMS (microelectromechanical system) technology is introduced. Fabrication process of the proposed antenna is comprised of bulk and surface micromachining. Patch of the antenna is deposited over a silicon platform. The platform is created by structuring the silicon membrane which is formed through bulk micromachining of a silicon chip. The patch and the platform beneath it are discretized to facilitate their vertical displacement over underside air gap. Thermal actuation is used as driving mechanism. Operational mechanism of the antenna is such that by downward relocation of the patch, its resonant frequency shifts downward. Thermal actuators are connected to the platform and applying voltage to them cause downward shift in resonant frequency of the antenna. FEM (finite element method) simulations confirm mechanical and microwave performances of the antenna which are investigated by theoretical analyses. From mechanical point of view, antenna has tolerable mechanical stability and microwave point of view indicates that return losses are good (below $-$ 10 dB) and radiation patterns are very close to each other with reasonable gains. Moreover VSWR is less than 2 throughout the frequency tuning range. In the proposed antenna by applying a CMOS compatible voltage in the range of 0–4.5 V to each thermal actuator, the resonant frequency of the antenna shifts from 17.37 GHz in up-sate position to 15.07 GHz in down-state position. As a result of this frequency shift, a frequency tuning range of 2.3 GHz with bandwidths of 3.9 % in up-state and 1.4 % in down-state positions is achieved.