The Finite-Difference Time-Domain (FDTD) method is a computational electromagnetic technique for solving for the electric and magnetic fields in arbitrary spatial domains in the time domain. In contrast to techniques such as the Finite Element Method (FEM) and the Method of Moments (MoM), this technique is straightforward to understand and is simple to program.
Arudimentary 2D TMz code is included in Section 5 and is used to illustrate the main features of the method.
A rudimentary FDTD code (fdtd 1) has been written in MATLAB and is included in Section 5. Various examples using this code will be investigated in this section.
You need to submit a short report, no more than 5 sides of A4 excluding ?gures, answering the following questions. Each answer is expected to contain carefully thought out discussions and include references from the state of the art literature.
1. Investigate the behaviour of a di?racting knife edge. Is this result as expected? Which theoretical model did you use for comparison? (Hint: A knife edge can be speci?ed by setting pec blocks = [200 1 201 200].)
2. Investigate the behaviour of a parallel plate waveguide. (Hint: A parallel plate waveguide can be constructed from two PEC blocks using the following code:
pec_blocks = [50 10 380 200;
50 (200+dgap) 380 380];
where dgap is the width of the waveguide. A value dgap = 20 will allow the fundamental mode to propagate at 1 GHz, whereas a value dgap = 8 will be cuto? at 1 GHz.)
3. When implementing the FDTD method, it is important to select a lattice size that is sufficiently small. Explore the consequences of choosing a lattice size that is too large.
(Hint: Make the following change to example1 in the header: samples per wavelength = 5 to use only 5 samples per wavelength, and to compensate for the di?erence lattice size move the source to xs idx = 20 and ys idx = 50. How does the result di?er to that in Section 3.1?)