Design,fabrication and measurement of triple band frequency reconfigurable antennas for portable wireless communications

In this paper two triple-band monopole antennas are proposed for portable wireless applications such as WiFi, WiMAX and WLAN. Two different geometrical structures are used for the radiating elements of these antennas, each printed on a low cost FR-4 substrate. Truncated metallic copper ground is used to attain optimum radiation pattern and better radiation efficiency. The frequency of the antennas is reconfigured using a lumped-element switch. The proposed antennas covers three frequency bands 2.45, 3.50 and 5.20 GHz depending upon the switching conditions. Both antennas works with an optimum gain (1.7–3.4 dB), bandwidth (6–35%), VSWR (<1.5) and radiation efficiency (85–90%). Due to its affordable size (1.6 × 35 × 53 mm³), the antennas can be used in modern and portable communication devices such as laptops, iPads and mobile phones. The prototype of the antennas are fabricated and the measurements and simulations are found in close agreement.     

2450MHz医用微波辐射天线的设计

设计了一种工作在2450MHz频率的新型的医用微波热疗天线。采用有限元数值分析方法针对人体肌肉组织微波热疗模型,对单极辐射天线和改进的挽袖圆顶辐射天线在肌肉组织中产生的电磁场分布及单位质量电磁能量吸收率(SAR)进行了模拟计算,并且比较了挽袖圆顶天线和挽袖天线在2-3GHz频率之间的S11值。结果显示:挽袖圆顶天线通过优化的挽袖结构,减少了天线的能量反射,能量的分布不会随天线插入组织深度的不同而引起变化,优化的顶部结构可得到更好的反射特性。     

Design and realization of low profile dual-wideband monopole antenna incorporating a novel ohm (Ω) shaped DMS and semi-circular DGS for wireless applications

In this paper, a compact microstrip line fed dual-wideband printed monopole antenna (PMA) for wireless communication applications is presented. The proposed antenna consists of an asymmetric rectangular patch via a microstrip-fed line, an ohm (Ω) shaped DMS loaded at the rectangular patch, and dual semi-circular shaped DGS embedded in the partial rectangular ground plane. The combination of an ohm shaped DMS and two semi-circular DGS is used to broaden the bandwidth of the two bands and improve the return loss for the desired antenna. The measured 10 dB bandwidth for return loss are achieved to be 21.52% (3.40–4.22 GHz) and 47.32% (5–8.1 GHz) in the lower and upper band, respectively which covers the bandwidth requirements of 5.2/5.8 GHz WLAN and 3.5/5.5 GHz Wi-MAX application bands. Furthermore, the proposed antenna has a very simple planar structure and occupies a small area of only 621 mm² (23 mm × 27 mm). The proposed antenna has a desirable VSWR level, radiation pattern, radiation efficiency and gain characteristics which are suitable for wireless communication applications.     

A printed monopole ellipzoidal UWB antenna with four band rejection characteristics

An antenna design with four band rejection characteristics for UWB application is demonstrated. The proposed unique UWB antenna has shape of an embedded ellipse at top of trapezoidal patch (named as ellipzoidal), 50 Ω impedance microstrip line feed and a truncated beveled ground plane. To realize four band stop characteristics, three inverted U-shaped and a single I-shaped slots each of half guided wavelength are utilized on radiating element. The fabricated antenna has dimensions of 27 mm × 36 mm × 1.6 mm. This four band notched ellipzoidal UWB antenna has measured frequency bandwidth 2.8–14 GHz for magnitude of S₁₁ < −10 dB level. The measured ellipzoidal antenna exhibits four band rejection characteristics for magnitude of S₁₁ > −10 dB at 3.55 GHz for WiMAX band (3.26–3.9 GHz), 4.55 GHz for ARN band (4.35–5.05 GHz), 5.7 GHz for WLAN band (5.5–6.65 GHz) and 8.8 GHz for ITU-8 band (7.95–9.35 GHz). The proposed ellipzoidal UWB antenna maintains omnidirectional radiation pattern, gain, linear phase response, <1 ns group delay, and transfer function in the whole UWB operating bandwidth except at notched frequency bands.     

Multi band multi polarized reconfigurable circularly polarized monopole antenna with simple biasing network

Design of a reconfigurable multiband multi polarized monopole antenna with simple bias circuit is presented. The proposed antenna consists of simple radiating truncated rectangular patch with a cross-shaped slit and a ground plane embedded with L-shaped slit. The antenna produces two separate impedance bandwidth with three senses of polarization namely right hand circular polarization, left hand circular polarization and linear polarization. PIN diode is used to reconfigure the L-shape slit in the ground plane. The antenna generates dual band behavior with multiple circularly and linearly polarized bands. With OFF state of the diode, the impedance bandwidth of the antenna is 10.22% and 83.43% from 3.99 GHz to 4.42 GHz and 5.84 GHz to 14.20 GHz, respectively, while 3-dB axial ratio bandwidths are 9.83% and 13.73% from 5.79 GHz to 6.39 GHz and 8.49 GHz to 9.74 GHz, respectively. In the ON state, antenna also shows the dual band behavior with an impedance bandwidth of 49.10% and 21.31% from 7.20 GHz to 11.04 GHz and 12.66 GHz to 15.37 GHz, respectively, while 3-dB axial ratio bandwidth of 6.49%, 8.45% and 2.0% from 7.90 GHz to 8.43 GHz, 10.08 GHz to 10.97 GHz and 12.87 GHz to 13.13 GHz, respectively.     

Analysis of monopole antenna on circular disc by mode matching

Mode matching is used for the analysis of monopole antenna on circular disc, which is achieved by developing a novel model consisting of two artificial ground planes above and bellow the monopole antenna. Using this model, the input impedance is computed and compared with measured data reported in literatures, and excellent agreement is observed.     

平面双频单极天线研究

研究了一种小型化的平面双频天线,利用一个斜F加倒L图形结构并通过在天线结构中的电感平衡加载来设计一种平面单极双频天线.它具有接地板小且天线低端谐振点频带宽的特点,为平面双频单极天线的小型化设计提供了一种新的方案.     

On the design of inscribed triangle circular fractal antenna for UWB applications

In this article, an ultrawide band inscribed triangle circular fractal antenna is presented. The antenna has been designed on FR4 substrate dielectric constant ?_r = 4.3 and thickness of substrate 1.53 mm with initial dimension of 30 mm diameter. The experimental result of fractal antenna exhibits the excellent ultra bandwidth from 2.25 GHz to 15 GHz corresponds to 147.83% impedance bandwidth at VSWR 2:1. This ultrawide band characteristcs of antenna has been achieved by using the CPW-fed and fractal concept. The measured radiation pattern of fractal antenna is nealy omnidirectional in azimuth plane and bidirectional in elevation plane. The measured group delay of proposed antenna is almost constant throughout the band. Such type of antenna is very useful for UWB communication system.     

考虑初始几何缺陷正十二边形单管塔插接节点性能

近年来插接式单管钢塔已在电力线路、通讯和交通照明等各个行业中得到大量的应用,其插接节点本身存在一定的初始几何缺陷。本文提出了三种简化的初始几何缺陷模式,借助有限元分析软件ANSYS,分析了节点初始几何缺陷对正十二边形单管塔插接节点的抗弯刚度和抗弯极限承载力的影响。     

快速拼装、可搬迁通信铁塔预制基础研究

本文提出两种新型的通信铁塔预制基础的结构形式,介绍了其拼装、组合原理、施工过程及设计计算要点,并通过工程实例实现了通信基站铁塔的快速部署及可搬迁。