The simulation and analysis capabilities of Applied Electromagnetics is built around a collection of Electromagnetic modelling tools. GAEL is a general purpose Finite Difference program for solving Maxwell's equations. It employs the Yee algorithm at its core and has the ability to model many shapes built up from generic objects. There are versions that run in one, two or three dimensions according to the demands of the problem.
The basic capability for solving Maxwell's equations is supplemented by a range of models that exist within the code for representing sub-celluar features and for performing transformations. Thin wires, slots and sheets can all be represented by analytic models incorporated into the finite difference scheme. Incident plane waves are produced in the mesh by use of a Huygens Surface. This allows the waves in the main part of the mesh but only the scattered field is present around the edges facilitating the differentiation of the incident and reflected components. Often the scattered signal in the far field is required. To avoid the necessity of using large amounts of memory to map empty space the code incorporates a transform which maps the near field scatter to what would be seen in the far field.
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Typical applications are for antenna design studies and for scattering problems. A problem that AEL is actively involved in is the detection of land mines. Modern mines are made predominantly of plastic and so they are invisible to conventional mine detectors. There is a lot of interest in the use of Ground Penetrating Radar to detect the mines and AEL have been heavily involved in both antenna work and radar signature characterisation of mines. Initial studies with cylinders show the propagation of a radio pulse through a mine. |
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Once the basic principles are understood an accurate model of a mine can be constructed. |
| The calculated signature of this mine has been compared to experimentally measured signatures and the agreement is excellent. |