共查询到19条相似文献,搜索用时 125 毫秒
1.
采用矩量法(MM)结合二致性几何绕射理论(UTD)的混合方法计算了机载单极天线的辐射方向图。该混合方法建立的机载天线辐射模型更符合实际,并且它同时具有MM的精确性和UTD的高效率,克服了单一方法的不足。计算结果对于预测天线间的电磁兼容性和优化天线布局具有一定的指导意义。 相似文献
2.
3.
4.
5.
6.
7.
采用矩量法(MOM)结合一致性几何绕射理论(UTD)来分析和计算大型平面阵列天线的辐射特性。大型天线阵列含有很多的辐射单元,单独应用矩量法求解时,未知数太多,计算速度慢。而应用MOM-UTD混合方法,未知数的数量大大少于单独用矩量法时的未知数的数量。本文以振子组成的平面阵列为例,说明该方法如何应用。最后给出了数值解的结果,并与单独用矩量法得到的结果进行了比较。比较表明,该方法是有效的、准确的。 相似文献
8.
9.
10.
并行UTD算法及在机载天线分析中的应用 总被引:5,自引:2,他引:3
要实现对复杂环境的EMC分析,最大的障碍是计算量过大,耗时太长.本文提出MPI结合UTD的并行算法,实现了大型复杂飞行器机载天线的方向图特性分析.数值结果表明,并行UTD算法可以大大节省计算时间.这一方法为在小型机系统下实现大型EMC分析软件提供了坚实的基础. 相似文献
11.
High frequency techniques for antenna analysis 总被引:2,自引:0,他引:2
Pathak P. 《Proceedings of the IEEE. Institute of Electrical and Electronics Engineers》1992,80(1):44-65
A summary of various high-frequency techniques is presented for analyzing the electromagnetic radiation from antennas in the presence of their host environment. These techniques provide physical insight into antenna radiation mechanisms and are found to be highly efficient and accurate for treating a variety of practical antenna configurations. Examples to which these techniques have been applied include open-ended waveguide antennas, horn and reflector antennas, and antennas on aircraft and spacecraft. The accuracy of these techniques is established via numerical results which are compared with those based on other independent methods or with measurements. These high frequency methods can be combined with other techniques, through a hybrid scheme, to solve an even greater class of problems than those which can be solved in an efficient and tractable manner by any one technique alone 相似文献
12.
In this paper, we describe a technique for reducing the specific absorption rate (SAR) and human effects on antenna performance, based on combined use of rubber conductive composite loaded with carbon-silica hybrid filler used like a single director and a resonant half wave dipole. The finite-difference time-domain method was used to evaluate SAR and antenna performance for different antenna-composite configurations and distances. Bandwidth, gain, and radiation efficiency for different antenna-composite configurations were compared. It was found that the presence of a conductive composite loaded with carbon-silica hybrid filler can effectively reduce maximum SAR value (up to 70%) in a human head model, increasing the radiation efficiency (up to 67%) and the bandwidth (up to 110%) of the antenna. 相似文献
13.
介绍了一种特殊形状的飞行器通信天线——腰形天线。用曲线坐标系时域有限差分法(NFDTD)对该天线进行了分析,并给出了一种新诠释,所计算出的辐射特性与实测结果吻合较好。结果表明:该天线能保证飞行器在复杂机动飞行条件下通信联络的畅通,且较好地解决了喷口火焰对天线辐射特性影响的难题。 相似文献
14.
Huang Z. Demarest K.R. Plumb R.G. 《Geoscience and Remote Sensing, IEEE Transactions on》1999,37(6):2692-2698
Calculating the current distribution and radiation patterns for ground-penetrating radar antennas is a challenging problem because of the complex interaction between the antenna, the ground, and any buried scatterer. Typically, numerical techniques that are well suited for modeling the antennas themselves are not well suited for modeling the heterogeneous grounds, and visa versa. For example the finite-difference time-domain (FDTD) technique is well suited for modeling fields in heterogeneous media, whereas the method of moments (MoM) is well suited for modeling complex antennas in free space. This paper describes a hybrid technique, based upon the equivalence principle, for calculating an antenna's current distribution radiation pattern when the antenna is located near an air-ground interface. The original problem is decomposed into two coupled equivalent problems: one for the antenna geometry and the other for the ground geometry, with field information passing between them via a rapidly converging iterative procedure. The fields in each region may be modeled using numerical techniques best suited to them. Results for several test cases are presented, using FDTD to model the ground problem and MoM for the antenna problem, that demonstrate the accuracy of this hybrid technique 相似文献
15.
An accurate and efficient numerical solution is developed for predicting high-frequency radiation patterns of antennas mounted on curved surfaces. This solution employs the uniform geometrical theory of diffraction (UTD) and has mainly been used to analyze airborne antenna patterns. In this case the aircraft is modeled in its most basic form so that the solution is applicable to general-type aircraft. The fuselage is modeled as a perfectly conducting composite ellipsoid, whereas, the wings, stabilizers, nose, fuel tanks, and engines, etc. are simulated by perfectly conducting fiat plates. The composite-ellipsoid fuselage model is necessary to simulate successfully the wide variety of real world fuselage shapes. Since the antenna is mounted on the fuselage, it has a dominant effect on the resulting radiation pattern, so it must be simulated accurately, especially near the antenna. Various radiation patterns are calculated for military aircraft, private aircraft, and the space shuttle orbiter. The application of this solution to practical airborne antenna problems illustrates its versatility and design capability. The solution accuracy is verified by the comparisons between calculated and measured data. 相似文献
16.
A new approach to the modelling of aircraft wings, based on the combination of hybrid quadric (parabolic and circular) cylinders, has been presented for electromagnetic applications. Closed-form expressions have been obtained for ray parameters required in the high-frequency mutual coupling computation of antenna pairs located arbitrarily on an aircraft wing 相似文献
17.
机载天线是飞机导航、通信等系统的重要组件;实现远距离通信主要依靠机载短波天线。新型复合材料的使用以及飞机尺寸的增大,是国际飞机发展的潮流。针对这一问题,该文利用电小天线及传输线相关理论设计一种新型大型飞机机载隐蔽式短波天线,设计过程中使用电磁仿真软件Ansoft HFSS建模计算天线输入阻抗及方向图并优化天线尺寸;在此基础上,制作缩比模型并在微波暗室中对其进行实测,所得数据与仿真结果相符。除此之外,对天线的阻抗匹配及效率进行分析并给出计算结果。计算及测试结果表明,此天线可与天线调谐系统(例如KHF950)良好调谐,方向图为水平全向,符合应用要求,可用于整个机身或仅垂尾为复合材料的大型飞机。 相似文献
18.
传统抛物面天线剖面高,而高速运动中的飞机需要具有低剖面特性的天线以减小其风阻。文中设计了一种Ku频段平板动中通天线,具有装机高度低、风阻小、性能优的特点。该天线阵列设计为35:1的长方形结构,大幅降低了高度。天线阵列采用高效率辐射单元,天线单元通过低损耗的带状线与波导结合形式馈电进行组阵。方位跟踪采用相控电子波束扫描技术,俯仰采用程序引导跟踪技术。测试结果表明,天线高度不超过280 mm,天线增益优于33 dB,跟踪精度误差控制在05 dB以内。 相似文献
19.
A wideband hybrid dielectric resonator antenna (DRA) is investigated experimentally. The proposed hybrid DRA comprises a rectangular dielectric resonator and a conductor-backed coplanar waveguide (CB-CPW) slot etched on a small ground plane. Dual resonances of the two radiators are merged to expand the antenna bandwidth. By utilising the CB-CPW structure, a back-cavity is formed underneath the slot to suppress the backward radiation. Hence consistent unidirectional radiation pattern is achieved across the matching band. 相似文献