Antenna Theory by Numeric Field Calculations

Computation of the current distribution and the input impedance of linear antennas and collinear antenna system by rigorous numeric methods. Corresponding formulae derived by extensive analytic calculations are implemented in FORTRAN program packages called GALNEC 1.1, GALNEC 2 and GALNEC 3. The method is based on the electric field integral equation, which is solved by the method of moments and Galerkin's method. End caps are hemi-spheres joined smoothly to the cylindrical main body. Basis and weight functions are trigonometric subdomain functions. Matrix elements are evaluated rigorously. The main object is to obtain accurate results for some simple test cases with which other codes may be compared for checks. Numeric design of an annular ring antenna fed by a directional coupler to emit circularly polarized waves.

Electromagnetic Fields of Charges Moving in Structures

The electromagnetic fields generated by charges moving in structures are computed by semi-analytic methods. These investigations have applications for fields generated by bunches moving through accelerating cavities or to signal generation in counters. Fields are expressed in series which are summed numerically.

Theoretical Atomic Spectroscopy

The Stark-Zeemann effect of the hyperfine structure of alkaline and similar atoms is investigated for weak crossed fields. The energy surfaces as functions of the electric and magnetic field strengths are computed and plotted. This reveals where these surfaces are connected. This leads to a clear explanation of crossings and anticrossings. It is intended to search for the occurence of geometric phases.

Computing and Plotting Static Electromagnetic Field Distributions by Conformal Maps with the Help of Mathematica

Field distributions between electrods or pole pieces are computed with the help of conformal maps. These are implemented in Mathematica programs employing the add-on package GraphicsOEComplexMapOE.These programs are selfcontained and can be started immediately by any user having little knowledge of Mathematica or conformal maps. The geometric parameters of each configuration are contained in a program head so that the user can adapt the geometric dimensions to his needs within tested limits. The programs give qualtitative and quantitative diagrams of potential and field distributions, also the fields along the boundaries. At the end one can give the coordinates of a point and the programs computes the values of the potential and of the field at this point.Programs have been or are developed for the following two-dimensional configurations: the end of a pol piece with a sharp rectangular or with a rounded edge; the end of a plane condensor with infinite thin plates or with plates of equal finite thickness; an aperture in an infinite thin screen or in a screen of finite thickness; a channel with a sharp rectangular bend changing the width of the channel; a channel changing its cross section by a sharp rectangular step; an infinitely thin stripline in front of an infinite plane; an infinitely thin stripline in line with two semi-infinite thin planes; a circular cylinder in front of an infinite plane; two parallel cylinders with different radii. These programs are available on a web-site.