********************* Numerical comparisons ********************* This section presents some comparisons of models using different numerical modelling techniques. FDTD/MoM ======== The Finite-Difference Time-Domain (FDTD) method from gprMax is compared with the Method of Moments (MoM) from the MATLAB antenna toolbox (http://uk.mathworks.com/products/antenna/). Bowtie antenna in free space ---------------------------- This example considers the input impedance of a planar bowtie antenna in free space. The length and height of the bowtie are 100mm, giving a flare angle of :math:`90^\circ`. FDTD model ^^^^^^^^^^ :download:`antenna_bowtie_fs.in <../../tests/numerical/vs_MoM_MATLAB/antenna_bowtie_fs/antenna_bowtie_fs.in>` .. literalinclude:: ../../tests/numerical/vs_MoM_MATLAB/antenna_bowtie_fs/antenna_bowtie_fs.in :language: none :linenos: A Gaussian waveform with a centre frequency of 1.5GHz was used to excite the antenna, which was fed by a transmission line with a characteristic impedance of 50 Ohms. The module ``plot_antenna_params`` from the ``tools`` subpackage was used to calculate and plot the input impedance from the FDTD model. MoM model ^^^^^^^^^ The bowtie antenna was created using the antenna toolbox in MATLAB, and the ``bowtieTriangular`` class. .. code-block:: matlab bowtie = bowtieTriangular('Length', 0.1) zin = impedance(bowtie, 33.33e6:33.33e6:6e9) Results ------- :numref:`antenna_bowtie_fs_ant_params` shows the input impedance (resistive and reactive) for the FDTD (gprMax) and MoM (MATLAB) models. The frequency resolution for the FFT used in both models was :math:`\Delta f = 33.33~MHz` .. _antenna_bowtie_fs_ant_params: .. figure:: ../../tests/numerical/vs_MoM_MATLAB/antenna_bowtie_fs/antenna_bowtie_fs_ant_params.png :width: 600 px Input impedance (resistive and reactive) of a bowtie antenna in free space using FDTD (gprMax) and MoM (MATLAB) models. The match...