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Title: EMAP5: A 3D Hybrid FEM/MOM Code
Abstract: EMAP5 is a numerical software package designed to model electromagnetic problems. It employs the finite element method (FEM) to analyze a volume, and employs the method of moments (MoM) to analyze the region exterior to the FEM volume. The two methods are coupled by enforcing the continuity of the tangential fields on the interface. Dielectrics, lossy dielectrics, and metal objects can be modeled within the FEM volume. Metal objects can also be located exterior to, or on the surface of the FEM volume. A simple input file translator (SIFT) is provided with EMAP5 that allows users to define basic input configurations on a rectangular grid without a graphical interface. It is also possible to use commercial mesh generators to analyze more complex geometries of arbitrart shape. EMAP5 can model three types of sources: incident plane waves, voltage sources on metal patches and impressed current sources in the finite element region. This paper describes the implementation of EMAP5 and provides four examples to demonstrate the range of coonfigurations that EMAP5 is capable of modeling using the SIFT translator.
Author(s): Y. Ji, T. Hubing
File Type: Journal Paper
Issue:Volume: 15      Number: 1      Year: 2000
Download Link:Click here to download PDF     File Size: 3652 KB

Title: A Hybrid Mom/FEM Technique for Scatter from a Complexe BOR with Appendages
Abstract: A hybrid technique is developed to allow the scattering from small appendages to be approximately combined with the scatter from a large body of revolution (BOR). The hybrid technique thus enables the rotational symmetry of the large BOR to be exploited to solve the scattering problem with much less computational complexitity than a fully three-dimensional (3-D) solution. The technique combines the finite element method (FEM) for BOR scattering with the method of moments (MoM) for small appendages. The hybrid forumlation is discussed in detail, including an approximate Green's function with permits the decoupling of the solutions from the FEM and the MoM. Numerical examples are given to show the applicability and accuracy of the hybrid technique.
Author(s): Andrew D. Greenwood, Jian-Ming Jin
File Type: Journal Paper
Issue:Volume: 15      Number: 1      Year: 2000
Download Link:Click here to download PDF     File Size: 2981 KB

Title: Impedance of a half-wave dipole over a finite ground plane
Abstract: A study has been carried out on the impedance of a half-wave dipole above a finite ground plane. The Method of Moment code, NEC-4, has been used and it has been found that for ground planes which are greater than 1.0 by 1.0 wavelengths, the changes from the effect with an infinite plane are negligible. With very small planes, the current distribution across the ground plane and the impedance are substantially different from those with larger grouind planes.
Author(s): P R Foster, R A Burberry
File Type: Journal Paper
Issue:Volume: 15      Number: 1      Year: 2000
Download Link:Click here to download PDF     File Size: 1546 KB

Title: The Design of Planar Slot Arrays Revisited
Abstract: Design procedures for planar waveguide slot arrays have been known and used for years, but the inexperienced designer is often faced with a number of practical problems when trying to implement them, especially in the case of larger arrays consisting of sub-arrays. Some helpful hints concerning the numerical implementation are provided. These include an effective procedure to avoid the necessity of good initial guesses for the unknown dimensions and recommendations for the subdivision of the nonlinear equations into smaller groups. Other practical aspects which are not explicitly defined elsewhere in the literature, are also addressed.
Author(s): J.C. Coetzee, J. Joubert
File Type: Journal Paper
Issue:Volume: 15      Number: 1      Year: 2000
Download Link:Click here to download PDF     File Size: 3222 KB