49 lines
1.2 KiB
Matlab
49 lines
1.2 KiB
Matlab
function field = GetField_TD2FD(field, freq)
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% function field = GetField_TD2FD(field, freq)
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%
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% Transforms time-domain field data into the frequency domain
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% Autocorrects the half-timestep offset of the H-field
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%
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% example:
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% freq = linspace(0,1e9,100); %target frequency vector (Hz)
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% field = ReadHDF5FieldData('tmp/Ht.h5');
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% field_FD = GetField_TD2FD(field, freq);
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%
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% openEMS matlab interface
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% -----------------------
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% author: Thorsten Liebig
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%
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% See also ReadHDF5FieldData
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if (~isfield(field,'TD'))
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warning('openEMS:GetField_TD2FD','field has no time domain data... skipping FD transformation...');
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return
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end
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t = field.TD.time;
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dt = t(2)-t(1);
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clear field.FD
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field.FD.frequency = freq;
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for nf = 1:numel(freq)
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field.FD.values{nf} = 0;
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end
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numTS = numel(field.TD.values);
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for n=1:numTS
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for nf = 1:numel(freq)
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f = freq(nf);
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field.FD.values{nf} = field.FD.values{nf} + field.TD.values{n}.*exp(-1i*2*pi*f*t(n)) * 2 * dt;
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% t(n) is absolute time and therefore the half-timestep offset of
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% the H-field is automatically compensated
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% openEMS output: E-fields start at t=0
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% openEMS output: H-fields start at t=delta_t/2
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end
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end
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field.FD.DataType=1;
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