Analysis of Thin Wire Antennas.ppt
《Analysis of Thin Wire Antennas.ppt》由会员分享,可在线阅读,更多相关《Analysis of Thin Wire Antennas.ppt(62页珍藏版)》请在麦多课文档分享上搜索。
1、Analysis of Thin Wire Antennas,Author: Rahul Gladwin. Advisor: Prof. J. JinDepartment of Electrical and Computer Engineering, UIUC.,Introduction,When we design antennas, it is vital to be able to estimate the current distribution on its surface. From the current distribution, we can calculate the in
2、put impedance, gain and the far-field pattern for the antenna.,Introduction (cont),Theoretical calculations may be used to analyze antennas with simple geometry, however, as we begin to analyze coupled antennas, the work becomes more tedious. It becomes necessary to numerically model the antenna to
3、determine its current distribution.,Introduction (cont),In this project, I have written a MATLAB program to model the current distribution on thin-wire single and coupled one-dimensional antennas. The algorithm used to evaluate the integrals is based on the Method of Moments and Halln-Pocklington eq
4、uations,Introduction (cont),To test my program, I have the modeled current distributions on a single dipole antenna and due to the mutual coupling between closely spaced linear antennas like those in a three-element Yagi-Uda array antenna.,Theoretical Formulation,This purpose of this program is to d
5、etermine the electric charge density and electric current density that result when an impressed electric field acts on a one dimensional thin wire antenna.,Theoretical Formulation (cont),Until now, weve assumed that J is known and we have solved for E. I have now turned this around and solved for J
6、using a known E. Where J is the current density and E is the electric field intensity.,Theoretical Formulation (cont),Obviously, E is not known anywhere, but we do know that Etan = 0 on the surface of the PEC (Perfect Electric Conductor).My further derivations take off from here.,Theoretical Formula
7、tion (cont),When studying antennas, we can run into two situations: receiving and transmitting antennas. A successful program should consider both these situations and the differences, if any, should be incorporated in the algorithm. I started by drawing the two scenarios and writing out the respect
8、ive equations.,Transmitting Antennas,Receiving Antennas,Theoretical Formulation (cont),The important thing to realize is that whether were dealing with either of the two situations, the impressed Electric field induces a current J to flow on and in the wire. J(r), in turn produces a scattered field
9、Es. The total electric field produced is E=Ei+Es.,Theoretical Formulation (cont),For simplicity, I assumed the wires to be perfectly conducting. Thus, the tangential component of the total field must be zero on perfectly conducting wires. This leads to an integral equation that can be solved for J.
10、Once J is known, it can be used to find the required current distribution.,Theoretical Formulation (cont),Now, all I needed is the expression for Etan on the wire surface that is in terms of the unknown J.The first step is to find an equation relating E to J. It can be derived as follows.,Derivation
11、 for Escattered,Derivation for Escattered,Derivation for Escattered,Derivation for Escattered,Derivation for Escattered,The above is the exact solution,Simplifying assumptions,The wire is a PEC (Perfect Electric Conductor). Current flows only on the surface of the wire. Current only flows on the + a
12、xis and is uniformly distributed over the wire surface.,Simplifying assumptions (cont),The wire is thin. I assumed this to enforce that Etan= 0 on PEC wire. Both Ez and Ephi are tangential components but the thin wire assumptions dont allow a Ephi component. So I only cared about the z-component of
13、Etan.,Simplifying assumptions (cont),From the previous assumptions, I can write the current density within the wire as:,Simplifying assumptions (cont),After enforcing Etan = 0; by symmetry, Etan = Ephi Again, putting down only the z-component of the scattered electric field equation, we get:,Simplif
14、ying assumptions (cont),Simplifying assumptions (cont),This is my main equation for evaluating Ez. However, there is a problem with the above equation: a singularity exists.,Simplifying assumptions (cont),Simplifying assumptions (cont),Integral Equation of the First Kind is found:,Note that the prev
- 1.请仔细阅读文档,确保文档完整性,对于不预览、不比对内容而直接下载带来的问题本站不予受理。
- 2.下载的文档,不会出现我们的网址水印。
- 3、该文档所得收入(下载+内容+预览)归上传者、原创作者;如果您是本文档原作者,请点此认领!既往收益都归您。
本资源只提供5页预览,全部文档请下载后查看!喜欢就下载吧,查找使用更方便
2000 积分 0人已下载
下载 | 加入VIP,交流精品资源 |
- 配套讲稿:
如PPT文件的首页显示word图标,表示该PPT已包含配套word讲稿。双击word图标可打开word文档。
- 特殊限制:
部分文档作品中含有的国旗、国徽等图片,仅作为作品整体效果示例展示,禁止商用。设计者仅对作品中独创性部分享有著作权。
- 关 键 词:
- ANALYSISOFTHINWIREANTENNASPPT
