This paper investigates the effect of an external plane wave on a Multi-conductor transmission line (MTL) located above a multilayer soil directly in the time domain. An improved finite-difference time-domain (FDTD) method is used, in conjunction with the Vector Fitting (VF), to obtain the recursion relations of voltages and currents along the line by discretizing the equations in time and one-dimensional space. The source terms of the coupling equations are efficiently obtained in the time domain based on the Gaver-Stehfest algorithm. An equivalent model is also established in this work, where the geometry with three conductors is reduced to two conductors. Finally, some examples are presented to illustrate the effect of the soil and the plane wave on the transient.
A coplanar waveguide (CPW) fed multiple-input multiple-output (MIMO) ultra-wideband (UWB) antenna with high isolation and dual band-notched characteristic is proposed. The antenna consists of two orthogonal circle patches. An annular SRR slot and a rectangular SRR slot are added on the patches to produce two notched bands. High isolation is successfully acquired by adopting a double Y-shaped branch between the two radiation elements. By cutting the fractional substrate, the antenna size has been reduced by 31.4 percent. The measured results show that the working bandwidth of the antenna covers 2.36-12 GHz, and at the same time, the notched bands cover 3.37 GHz-3.98 GHz and 4.71 GHz-5.51 GHz. The isolation is better than 21 dB. The paper also studies the radiation pattern, peak gain, and envelope correlation coefficient (ECC) of the UWB MIMO antenna.
Owing to its all-day and all-weather imaging capabilities, high-resolution spaceborne synthetic aperture radar has shown great potential for the effective monitoring of wide-area, ultra-high-voltage (UHV) transmission lines. Scattering characteristics of UHV power lines in 3-m-resolution TerraSAR-X images is analyzed in this paper. First the study area and structure of the UHV transmission line are introduced. Then, the data processing method is described, which includes the preprocessing of TerraSAR-X images and target feature extraction. Finally, the scattering characteristics of the UHV power line are analyzed, and the analysis results demonstrate that the UHV power line can be visible in a TerraSAR-X image only when the angle between its extension direction and the azimuth of the sub-satellite ground track is within ±15°. Furthermore, besides the span length, the spatial location of the UHV power line in a TerraSAR-X image is also influenced by the angle between its extension direction and the azimuth of the sub-satellite ground track, as well as by the height difference between adjacent pylons.
Modern combat teams face an increasingly complex battlefield, where threats may arise from a number of different sources. Examples include not only conventional attacks through rocket propelled grenades but also improvised explosive devices and weaponised unmanned aerial vehicles. Combat teams can now be equipped with sophisticated surveillance and reconnaissance capability, as well as automatically activated defences. The focus of this paper is to consider the utility of collaborative active protection systems, which are designed to provide an active defence against threats to a combat team. Specifically, a general statistical framework for the analysis of such systems is introduced, with a particular focus on high power radio frequency directed energy weapon countermeasures. The mathematical model allows for a subset of the combat team to be responsible for target detection and tracking, and a time-varying subset of team members with suitable countermeasures to be specified separately. The overall probability of threat defeat and team survivability is then derived. Some examples are provided to investigate the utility of such systems.