甚低频发射天线的损耗电阻研究

甚低频发射天线结构庞大，但其尺寸与波长相比仍属于电小天线，它的辐射电阻较小，天线的损耗电阻对天线辐射效率影响较大；天线的损耗主要来自于地损耗电阻，本文根据单极型天线地损耗电阻的理论计算公式，对设计时需着重考虑的关键参数进行了分析，并借助数值仿真计算方法对某十三塔天线的实例进行了计算验证。     

甚低频发射天线多调谐模式研究

甚低频天线一般是工作于该频段的电小天线,且其辐射效率不高,为了满足远距离的通信要求,天线往往采用多组天线的方式来保证足够大的功率容量,因此,多组天线的同步调谐就至关重要,本文对多组天线多调谐方式进行了研究,并对其互耦效应及调谐过程进行了理论分析,并借助数值仿真计算对简化的多调谐山谷天线进行了计算验证,得到了一致的结果,...     

中波发射天线地网与设备接地

中波发射天线地网与设备接地谢根棣（湖南省永州市中波转播台４２５００６）１地网的作用估算天线的效率，就必须考虑导体损耗，绝缘子的介质损耗，垂直接地天线的接地损耗。大地是接地天线回路的一部份。当电流流过大地回到天线底部时，天线底部附近的电流很大。能量的损...     

甚低频发信天线电晕电压计算方法研究

文中研究了甚低频发信天线电晕产生的机理,分析了电晕电压发生时伴随的物理现象和化学反应,理论推导了甚低频发射天线电晕电压的计算方法,实例给出了天线导线取值与电晕电压的计算结果,指出电晕电压与天线导线的直径、导线表面的粗糙程度、导线所处位置的大气密度、通过导线的电流频率、淋雨状态及导线的冰渍情况有关。     

甚低频发射天线辐射性能计算与测量研究

针对目前甚低频发射天线辐射性能测量不准确的问题,对影响岸基甚低频发射天线辐射电场和磁场的各个场分量进行了分析计算。提出了在满足一定精度的要求下的甚低频辐射磁场和电场的最佳测试距离,且在夜间测试更为准确,并提出电场和磁场测试值可按照自由空间波阻抗关系相互转换的条件,为准确获取甚低频发射天线辐射性能提供了有实际意义的指导原则。     

楼顶中波小天线地网技术研究

本文提出一种楼顶小中波天线地网的解决方案,解决了楼顶小中波天线的稳定性难题,提高了小天线的辐射效率,并提供了试验方法和大量的实测数据来验证该方案的可行性,小型中波天线的地网的研究对中波天线小型化技术具有一定的借鉴和促进作用。     

基于阻尼振荡法的甚低频天线阻抗测量

为了准确测量甚低频发射天线在实际工作环境和工作频点上的输入阻抗,本文提出了一种基于RLC阻尼振荡法的阻抗测量方法,并推导了天线阻抗、电容、电感和电阻的测量公式;该测量方法可通过提高测量电压来提高测量信噪比和测量精度;测量系统谐振于被测天线的工作频点或其附近,使甚低频发射天线输入阻抗的测量值更接近天线在实际工况下的真实值.试验表明,本文提出的测量方法简单可行,具有较高的精度和稳定性,可实现甚低频发射天线输入阻抗的现场测量.     

T型甚低频多调谐发射天线电容与电感研究

甚低频天线理论认为,采用多调谐方式,T型甚低频多调谐天线可以基本按比例增加天线电容,在实际工程中常用五组或六组天线.本文利用甚低频天线输入电抗的实测值,计算了在不同频率下天线所呈现的等效电容和等效电感,研究了T型甚低频发射天线的等效电容、电感、功率容量与天线组数及频率之间的关系.研究结果表明T型甚低频多调谐天线的组数过...     

强噪声环境下测量甚低频天线阻抗方法的研究

比较了在强噪声环境下测量甚低频发射天线输入阻抗二种方法, 提出一种新的矢量谐振测量方法, 这种新方法比传统的阻抗电桥法具有更高的精度.在此基础上研制出基于计算机数据采集与处理的天线输入阻抗实际测量系统, 该系统通过对测量网络各节点电压采样与处理, 自动计算天线输入阻抗并显示在计算机上.实测结果表明, 该系统具有优良的精度和稳定性.     

Design of electrically small Yagi antenna

A two-element electrically small Yagi antenna is presented. The antenna is composed of a spiral-shaped driver and a director. To step up the low radiation resistance due to the small element size and close element spacing, multiple folded arms are used on the driver element. The design has been optimised, built and measured. The total volume of the antenna is 0.065lambdatimes0.095lambdatimes0.095lambda and the measured realised gain toward the director direction is 8.81 dB     

A method for computing the input conductance of an electrically small antenna

An expression based upon the effective aperture area of an antenna is derived which relates the input conductance at the feed point to an integral involving the magnitude of the short circuit current at the same point when the antenna is used as a receiving element. Using this relationship the input conductance for an evanescentTM_{01}circular waveguide mode inside and near the end of a finite-length thin (Omega = 2 ln (2h/a) = 10) cylinder is calculated over a wide range of electrical lengths including those for which the antenna is very short to those on the same order of a free-space wavelength, specificallykh = 0.05 to 3.5.     

Design of electrically small ground planes for HF ground wave transmission

Electrically small spiral ground planes for a monopole and an electrically small antenna have been designed for HF ground wave transmission. Prototype ground planes have been built and tested. For the monopole, the transmission loss of the designed ground plane is 6 dB better than that of the same size ground radials. For the electrically small antenna, the transmission loss of the designed ground plane is 7 dB better than that of the same size solid ground plane at the antenna's operating frequency.     

Quality factor of an electrically small antenna radiating close toa conducting plane

Expressions are derived for the smallest achievable radiation quality factor (Q) of an electrically small antenna in front of a conducting plane. Applying the low-frequency approximation to the source region involving an electric or a magnetic point dipole plus their images behind the plane, an expression is formed for the field in the radiation zone. The contribution of non-propagating energy in the near field is obtained explicitly using a spherical harmonics decomposition. The radiation Q is found to depend on the radius (relative to wavelength) of the smallest sphere that encloses the antenna and its image, the ratio of the vertical and horizontal dipole moments, as well as the positions of the dipoles relative to each other and to the plane. A number of simple wire structures are analysed with NEC (based on the method of moments), and the approximate Q obtained from their fractional bandwidth are compared to the corresponding theoretical minima     

Singular integral equation solution for electrically small short cylindrical antenna

It is shown, that in the case of the electrically small tubular cylindrical antenna whose length-to-radius ratio is 0(1) or smaller, that the integral equation involved readily reduces to a simple, singular equation, the solution of which is in terms of elementary functions.     

Improved slow-wave active transmitting antenna with photonic band-gap and defected ground structure

This paper presents an improved active transmitting antenna. Defected ground structures (DGSs) are used to eliminate the higher mode radiation. Slow-wave propagation is realized by adopting DGS and photonic band-gap (PBG) structure, and consequently, size reduction is achieved. Suppression of the excited surface-waves of the patch antenna is realized by using an array of rectangular PBGs. Higher mode reduction is realized by using DGS. Measurement results are presented and discussed.     

DARPA机械天线项目或掀起军事通信革命

为突破传统“电源型”天线尺寸微缩难、阻抗匹配难、辐射效率低等原理性桎梏,基于器件物理本质首次准确定义了体声波(bulk acoustic wave, BAW)介导的磁电(magnetoelectric, ME)耦合天线,即BAW ME天线. 这是一种新型“磁源型”天线或机械天线,其工作机理迥异于“电源型”天线,有望通过原理颠覆性创新根治这些问题. 在深入认识机械天线物理本质的基础上,对其进行了理论溯源、分类梳理. 以BAW ME天线为典型案例,综述了BAW ME天线技术的研究进展,分析了该技术所涉及的关键科学问题,进一步给出了解决这些问题的技术方案框架.     

Design of electrically small, pattern reconfigurable Yagi antenna

An electrically small, pattern reconfigurable Yagi antenna is designed fabricated and measured. Two directors are located on the two opposite sides of the driver. A pin diode is used on the bottom of the director to switch the beam pattern. The measured maximum realised gain of the antenna is 8.5 dB and the front-to-back ratio is 7 dB.     

Study of electrically small printed chakra (wheel) antenna

A novel printed antenna configuration in the form of a chakra (wheel) is presented. The antenna has many design parameters, such as axle radius, rim radius, and shaft location, and exhibits a very low design frequency which is five times smaller than that of a regular circular microstrip patch antenna of the same size