【作者】 张红旗；

【导师】 沈凯先； 潘威炎；

【作者基本信息】 中国科学院陕西天文台 ， 天体测量与天体力学， 2001， 博士

【摘要】 本论文从哈佛大学的Ronold W.P.King和美国东北大学的Sheldon S.Sandler同亚利桑那州大学的James R.Wait之间的学术争论问题出发，对垂直和水平电偶极子分别在涂敷有介质层的导电基底上激励的电磁场问题进行了深入研究，包括理想导电基底和非理想导电基底两种情况。现将作者在研究中所做的主要工作以及主要成果如下： 首先对垂直电偶极子在涂敷介质层的理想导电基底上所激励的电磁场进行了研究，在继承前人的研究结果上，深入分析了电磁场各分量积分表达式的特征和性质，根据复变函数理论和贝塞尔函数的特点，推导出了电磁场各分量的方便于数值计算的完整解析表达式，解决了King和Sandler与Wait之间所争论的学术问题。 本文结果说明，King和Sandler的研究结果中，确实如Wait所言，遗漏了一项吸附表面波（Trapped surface wave）。但是本论文得到的吸附表面波，并不是Wait在评论中所说的的表面波，而是由场分量的被积函数中所含有的极点的留数项产生的，而Wait却认为应该能够从F（p）函数中分离出一项以ρ^-1/2规律衰减的传播波数为k_o表面波。 本论文给出了表面波的传播波数与介质层的关系。表明从极点留数上得到的表面波，其传播波数和Wait所言不同，既不是空气中的k_o也不是介质中的k_l，而是介于k_o和k_l之间，除主要与工作频率和介质层的厚度有关外还与介质层的介电常数和导电率有关，由被积函数所满足的极点方程决定。只是其扩散衰减规律和Wait所言相同，也是ρ^-1/2。 作者的结果还说明，被积函数的极点个数与介质层的厚度和介质层的波数k_l的乘积有关，当介质层的参数满足（k_l取其实部，以下相同）条件时，被积函数将有n个极点，也就是说吸附表面波将会有n个传播模式，而Wait的分析是单模式。 本论文得到的侧面波，扩展了King和Sandler结果的适用范围，没有对覆盖在导电基底上的介质层的厚度加以任何限制，而ing和Sandier的研究是将介质层的厚度限制在片尸X1或者久1＜0石条件下。 作者在上述研究基础上，又进行了更深一步的研究．分别对垂直电偶极子在涂敷介质层的非理想导电基底上激励的电磁场、水平电偶极子在涂敷介质层的理想导电基底上激励的电磁场和位于覆盖有介质层的非理想导电基底中的水平电偶极子在导电基底一侧激励的电磁场进行了深入研究，分别得到了这几种情况下电磁场各场分量完整的解析表达式。 作者的研究结果还表明，在一般情况下，水平电偶极子激励出的电型表面波和磁型表面波的传播被数是不相同的，其中的电型表面波与垂直电偶极子激励的规律相类似，而磁型表面波只有当介质层满足J厅一庸1＞o．5。条件时才能被激励，并且在满足…－0．5)＜Jki－片 l＜n＋0．5江条件下磁型表面波将会有 n个传播模式。 被积函数的极点方程都是超越方程，作者提出了一种新的求解这些极点超越方程的简便方法。 本论文给出了吸附表面波的传播波数在几种情况下的变化规律，并进行了大量的数值计算，从计算结果中可以看出明确的物理意义。更多还原

【Abstract】 The exact analysis expressions of the electromagnetic fields generated by a vertical or a horizontal electric dipole in the air over or on a perfect or an imperfect conductor coated with a dielectric layer have been obtained in this thesis. And the electromagnetic fields generated by a horizontal electric dipole in the imperfect conductor have been discussed too. The author抯 studies is inspired from the academic arguments of Ronold W. P. King of Harvard University, Sheldon S. Sandier of the U. S. A. Northeastern University and James R. Wait of the University of Arizona in the field of radio-wave propagation. The main contributions of author抯 work are as follows: Firstly, The electromagnetic fields of a vertical electric dipole on a perfect conductor coated with a dielectric layer have been discussed. The properties and the characters of integral expressions of the electromagnetic field components are through analyzed. And according to the theory of complex function and the characters of the Bessel functions, the exact analysis expressions of the electromagnetic fields in the air on a perfect conductor coated with a dielectric layer have been derived. It is easily to evaluating the values of each filed components by these formulas. The debating problem between K&S (R. W. P. King and S. S. Sandier) and Wait is resolved by the author抯 studies. The author抯 conclusion also shows that K&S have overlooked that a trapped surface wave can be excited by the source for the case where the coating layer is a low-loss dielectric and the substrate is a highly conducting half-space in their paper But the conclusion of this thesis is that the trapped surface wave is derived from the residues of the poles of the integrands of the field components, and is not derived from the F(p) function. However Wait claims that the trapped surface wave is derived from the F(p) function, and will vary with ji? over a major distance range and its wave number is same as the wave number /c0 in the air. The relations between the wave number of the surface wave and the parameters of the dielectric are given in this thesis. The amplitude of the trapped surface wave in this thesis attenuate as p~?2 along the surface of dielectric, coincide with that of comments of Wait. The propagation wave number of trapped surface wave in this thesis is different to that in the comments of Wait, and it is neither the wave number ~ in the air nor the wave number k1 in the dielectric layer, but it is a value between k0 and k~ Furthermore, it correlates with the frequency f~ the permittivity e~., the III ? conductivity a and the thickness of the dielectric layer, and it is determined by the poles equation of integrand of these formulas. The conclusions of the author show that the number of poles of the integrand depends on the thickness of the dielectric layer and the wave number k1 in the dielectric. When in this condition as (n ?l)r < ?k~ 1 <nir, there are n poles in these integrands, therefore, there are n modes of trapped surface wave in this case. In addition, the lateral wave obtained in this thesis spread the result of K&S. The thickness of the coating layer is not limited in this thesis, and the coating thickness is limited as k1212 ? or k1 / <0.6 in their paper更多还原