基于遗传算法的套筒单极子天线的优化设计

研究了套筒单极子天线的优化设计。文中采用将圆盘地面和套筒单极子天线整体分析的计算模型 ,运用矩量法结合基于小生境技术的遗传算法对其进行优化设计。最后 ,设计出一种工作在 110 - 390MHz频段、VSWR <3.0的实用套筒天线 ,分析计算结果与实验结果吻合良好 ,验证了本文方法的有效性和实用性。     

一种改进型套筒单极子天线的研究

文中基于单极粗振子展宽带宽理论,采用一种新型加粗套筒单极子辐射体的实用模型来展宽套筒单极子天线的阻抗带宽,并利用有限元法(FEM)对其驻波和辐射特性以及天线各参数进行了分析。在此基础上,设计了一副工作在108MHz～420MHz频段、电压驻波比小于3．0的实用套筒单极子天线,计算结果与实测结果吻合良好。     

精确分析任意导体地面上的套筒单极子天线

利用矩量法分析任意形状导体地面上的套筒单极子天线.对面结构选用三角形面元矢量基函数,对细线结构选用三角基函数,对线面结合处采用一种特殊的基函数,将导体地面和天线作为整体进行分析,大大提高了分析计算的精度.分别分析了两付位于圆形和方形地面上的实用套筒天线,其数值计算结果与实验结果或软件模拟结果吻合良好,表明了该方法的有效性.     

快速计算套筒单极子天线

利用矩量法分析计算套筒单极子天线的电性能参数。采用与实际天线较为接近的矩量法分析模型和一种新的粗圆柱线天线快速精确计算模型,大大提高了分析计算的精度;引入「Ｚ」矩阵插值法,提高了分析计算的速度。将该方法与最优化技术相结合,设计出一付工作在２００～７００ＭＨｚ频段、ＶＳＷＲ〈２．６、增益Ｇ〉５．１ｄｂ的实用套筒单极子天线,理论分析与实验测试吻合良好,从而说明了该方法的有效性和实用性。     

一种新颖的套筒单极子天线

介绍了一种新颖的套筒单极子天线,对其驻波比和辐射特性进行了分析,并通过改变其辐射体在套筒以上部分的结构,有效降低了天线的高度以适应实际应用,实现了展宽套筒单极子天线的阻抗带宽,所设计的天线实现了4倍频工作带宽,并具有较好增益.     

开放式套筒单极子手持天线的设计与验证

设计了一种阶梯结构、集总加载的辐射体、双弧形金属片围成半管状的开放式结构为套筒的开放式套筒单极子天线,天线具有良好的驻波比带宽.电磁仿真结果表明:在400~700 MHz的频带内,天线驻波比均优于2,天线在水平方向的增益均值高于0 dBi.实验测试结果与仿真结果具有良好的一致性,证明天线具有较好的辐射性能.     

新型套筒天线的研究与应用

采用矩量法分析了安装在金属圆柱筒上的套筒天线.研究了这种新型套筒天线的输入阻抗、电压驻波比(VSWR)、增益及辐射方向图等电特性.设计出了工作在105～420MHz频段和225～600MHz频段的实用天线,分析结果与实验结果吻合良好.     

一种两宽带天线共口径的设计

 给出了一种两宽带天线共用一个口径的设计.天线制作在420×200mm²的PCB板上,其中一副天线由阻抗加载的矩形及倒L形金属片构成,两者之间使用了一个低通匹配网络进行连接.此天线实现30~600MHz驻波比小于3的宽带匹配,其中86~110MHz之间为陷波设计.另外一副天线采用开式套筒结构,实现了800~1200MHz驻波比小于2.2的设计.利用天线1的低通匹配网络作为天线2的开式套筒,从而实现了共口径设计.     

浅谈UHF串馈套筒天线设计方法

本文在套筒单极子天线的基础上,对其馈电及结构进行变化,设计了一种UHF串馈套筒天线,并简要介绍了UHF串馈套筒天线的设计过程,利用仿真软件对其结构参数进行仿真分析,得出影响天线特性的参数规律,并通过组阵仿真得到较为理想的方向图,阐述了降低原料成本及提高电气指标的方法,在保证电气指标的前提下优化了天线结构。UHF串馈套筒天线VSWR≤1.2,优于国外同类天线VSWR≤1.4的指标。     

一种新颖的套简单极子天线

介绍了一种新颖的套筒单极子天线，对其驻波比和辐射特性进行了分析，并通过改变其辐射体在套筒以上部分的结构，有效降低了天线的高度以适应实际应用，实现了展宽套筒单极子天线的阻抗带宽，所设计的天线实现了4倍频工作带宽，并具有较好增益。     

Sleeve antenna with ground wires

Pocklington's integral equation for a sleeve antenna with ground wires is formulated. By applying the Galerkin method to this equation, a sleeve antenna, a monopole antenna with ground wires, and a sleeve antenna with ground wires are analyzed, and numerical results for these antennas are compared with measured data. The sleeve antenna features the leakage current on the surface of the coaxial feeder, suppressed by a sperrtopf, but it is mismatched with the 50-Ω feeder. The monopole antenna with inclined ground wires may be adjusted to match the 50-Ω feeder, but the leakage current induced on the feeder cannot be neglected. It is found that the sleeve antenna with ground wires has the advantages of both antennas     

VHF宽带小型化套筒天线的优化设计

研究了VHF宽带小型化套筒天线的设计与制作。采用遗传算法与模拟退火法相结合的优化方法，对套筒天线的结构参数以及宽带匹配网络的元件值进行一体化设计。分别采用外插收敛法、[Z]矩阵插值法以及小波变换法来提高矩量法分析计算天线的速度。利用该方法成功的设计了两副全向宽带小型化的套筒天线。     

A floating sleeve antenna yields localized hepatic microwave ablation

We report a novel coaxial antenna for hepatic microwave ablation. This device uses a floating sleeve, that is, a metal conductor electrically isolated from the outer connector of the antenna coaxial body, to achieve a highly localized specific absorption rate pattern that is independent of insertion depth. This floating sleeve coaxial dipole antenna has low power reflection in the 2.4-GHz IMS band. Ex vivo experiments confirm our numerical simulation results. Index Terms-Ablation, coaxial aperture antennas, finite element methods, floating sleeve, microwave heating.     

Energy deposition in simulated human operators of 800-MHz portable transmitters

The measured values of energy deposited in simulated human tissue exposed for one minute in the immediate vicinity of 800 MHz portable radio transmitters are presented. The deposited RF energy was evaluated by temperature measurements. The portable radio used in the tests had a 6-W experimental transmitter operating at 840 MHz. Two different antennas were tested for energy deposition: a sleeve dipole and a resonant whip. The two antennas have given substantially different results indicating different field structures near the two radiators. The experiments with flat slabs have shown that the sleeve dipole deposits higher levels of power density than the resonant whip in the near field although the length of the latter radiator is about half the size of the former. The temperature profiles generated by both antennas inside the head of the simulated operator indicate the presence of a "hot spot" about 1 in below the surface of the temporal bone. This phenomenon was not detected previously at lower frequencies. The short antenna exposes the eye of the operator to more intense power deposition than the sleeve dipole. The temperature increases measured during the investigation are so small that no thermal damage to tissue should be caused by normal use of the portable radio.     

一种套筒单极天线组成的宽带测向阵列

介绍了一种加粗的套筒单极天线,并作为测向单元使用。运用HFSS电磁仿真软件进行参数优化,在单元驻波与水平面增益满足工程情况下有效降低了天线高度。将这种套筒单极天线组成圆阵,在得出阵列电磁特性的基础上再运用最小二乘法分析了圆阵测向性能。结果表明,该测向天线阵在灵敏度、测向精度及阵列高度上都有一定的优势,特别适合于一些运动平台安装使用。     

复合材料垂尾隐蔽式短波天线研究

为研究复合材料垂尾对机载短波天线输入阻抗和辐射特性的影响,分析了不同机载隐蔽式短波天线的结构和性能,提出了一种基于复合材料垂尾的新型回线天线结构,并利用基于时域有限差分法的仿真软件XFDTD对这种位于机垂尾前缘的隐蔽式回线天线和传统的机载套筒天线分别进行了建模和仿真。根据仿真结果分析并总结出了复合材料垂尾对这两种机载短波天线输入阻抗和辐射特性的影响情况。通过与传统回线天线的比较,验证了新型回线天线的可行性和优势。仿真结果对实际机载短波天线的研究和设计有一定的参考价值。     

A dipole antenna for interstitial microwave hyperthermia

An improved interstitial microwave antenna design was investigated in static phantom experiments at 915 MHz and different insertion depths. Compared with conventional interstitial antennas, the presented dipole microwave antenna shows heating patterns which are concentrated on the dipole irrespective of the insertion depth. By analogy to interstitial radiotherapy, the microwave antenna allows a high concentration of energy in the target volume with as little damage as possible to the healthy surrounding tissue. The undesired heating of healthy tissue along the feeding line observed with conventional interstitial antennas is avoided. A λ/4 sleeve on the feeding line (which does not radiate microwave energy itself to the surrounding tissue) transforms an open end, i.e. a high impedance at the generator end of the dipole antenna. The current flowing back along the outside of the outer conductor of the feeding line in the direction of the generator is zero at this point. Both dipole sections have the same terminating impedance. Since the λ/4 sleeve is mounted outside the antenna, its mechanical length is not restricted by the mechanical length of the antenna. It can be charged with dielectric materials of low dielectricity constants     

Experimental study of embedded insulated antennas

Experimental studies are reported of several coaxial structures useful us embedded antennas and transmission lines. These include the insulated coaxial line with extended inner conductor, the insulated dipole with choke section, and the insulated sleeve dipole. The purpose of the experiments is to confirm theoretical calculations that involve numerous approximations.