{"id":53129,"date":"2021-03-10T12:14:20","date_gmt":"2021-03-10T12:14:20","guid":{"rendered":"\/forum\/forums\/topic\/ansys-insight-single-frequency-cw-source\/"},"modified":"2023-02-15T08:32:46","modified_gmt":"2023-02-15T08:32:46","slug":"ansys-insight-single-frequency-cw-source","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/ansys-insight-single-frequency-cw-source\/","title":{"rendered":"Ansys Insight: Single frequency CW source"},"content":{"rendered":"
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This topic describes the CW normalization used to convert time domain data to frequency (steady-state) data. The CW normalization option should be used whenever you collect frequency domain information.<\/p>\n

Solvers<\/strong>: FDTD, varFDTD<\/p>\n

See also:<\/strong><\/p>\n

Sources<\/a><\/p>\n

Units and normalization<\/a><\/p>\n

Frequency domain normalization<\/a><\/p>\n

Single frequency simulations in FDTD<\/strong><\/p>\n

Sources in FDTD always inject a pulse (i.e. broadband), even when the user is only interested in collecting data at a single frequency. Pulse sources are more efficient for collecting broadband information, and at least as efficient when collecting information at a single frequency. Therefore, there is no reason to use CW sources. The CW response of a structure can easily be obtained from a simulation that used a pulse source.<\/p>\n

The following screenshot shows the source Frequency\/Wavelength settings tab. In this screenshot, the source wavelength is set to a single frequency of 500nm. Even thought the frequency span is zero, a pulse is still used. The time domain signal of the pulse, and the associated power spectrum, are shown in the figures on the right side of the window.<\/p>\n

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<\/a>\"usr_cw_norm_single_frequency.png\"<\/a><\/div>\n
When the source frequency span is set to zero (i.e. single frequency), then the frequency domain monitors will automatically mearure the response of the system at that frequency only.<\/div>\n
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Creating a CW source<\/strong><\/div>\n
While we strongly recommend against using a CW source, it is possible to create them in FDTD. For example, it is possible to create a source time signal like the one shown below. For more information on creating custom source time signals, see the Creating a custom source time signal<\/a> page.<\/div>\n
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Your data analysis may be more complicated when using a CW source. The frequency domain normalization will not work properly with a CW source. The CW normalization requires that the time domain fields decay to zero by the end of the simulation.<\/div>\n
 <\/div>\n<\/div>\n<\/div>\n<\/div>\n","protected":false},"template":"","class_list":["post-53129","topic","type-topic","status-closed","hentry","topic-tag-fdtd"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t