Frequency domain field profile monitor (DGTD) - Simulation object

Frequency-domain EM field monitors collect information related to electromagnetic field data in the frequency domain from simulation from specific spatial region within the simulation in the DGTD solver. The spatial region can be defined as point, surface or volume and the data can be collected at multiple frequency points.

Additionally, this monitor directly provides information about Poynting vector, cross section and the power transmission through the monitor surface without the need to post-process the raw EM data.

Front and back parameters

Notice that some parameters provided by frequency-domain EM field monitors such as cross section and power transmission are returned with "front" and "back" attributes. The reason is that these parameters are related to two dimensional monitor surfaces that divide the simulation region into two partitions in front of and behind the monitors surface. These are often aligned with a boundary between two distinctive materials. As an example, we can imagine that the monitor represents a boundary between two materials with very different properties such as vacuum and metal. In this case, the data calculated from the regions directly in front of and immediately behind the monitor will differ. Therefore, the frequency-domain EM field monitors provide these parameters calculated on both sides. The "front" and "back" attribute is then decided by the solver based on the surface normals of given monitor. Surface normals are also provided in the monitor results for completeness. 

General tab

• USE LINEAR WAVELENGTH SPACING: By default, data is recorded at linearly spaced points with respect to frequency. Selecting this option spaces data at linearly spaced points with respect to wavelength.
• USE SOURCE LIMITS: When checked these monitors use the source limits. When unchecked, the frequencies/wavelengths at which to record data can be set using the pull down menus and boxes below them.
• FREQUENCY POINTS: Set to choose the number of frequency points at which to record data.

Geometry tab

Geometry type

• SURFACE
• VOLUME
• POINT

Volume, surface, line and point in 3D and 2D:

Surface Type

• DOMAIN:EXTERIOR : Select the target domain. The reference geometry is the common surface(s) shared by the uttermost surface(s) of the selected domain and the simulation region. The selected domain has to have at least a surface that is shared with one of the simulation region surfaces.
• DOMAIN:DOMAIN :  Select the target domains. The reference geometry is the common surface(s) shared by the two selected domains.
• DOMAIN : Select the target domain. The reference geometry is the surfaces of the selected domain.
• SOLID : Select the target solid. The reference geometry is the surfaces that enclose the selected volume if the solid is a 3D shape, or the surface if the solid is a 2D plane.
• SIMULATION REGION : Select one or more simulation region boundaries. The reference geometry is the selected boundaries.
• SOLID:SIMULATION REGION : Select one or more simulation region boundaries and the target solid. The reference geometry is the common surface(s) shared by the simulation region and the target solid.
• MATERIAL:MATERIAL : Select the target materials. The reference geometry is the surface(s) that is shared by the two selected materials. This is only available in some boundary conditions.
• SURFACE : Type the identifier of the partition surface. If the target partition surface is SURFACE 3, type 3. If the target partition surfaces are SURFACE 3 and SURFACE 5, enter 3,5.

Volume Type

• SOLID : Select the target solid. The reference geometry is the volume of the selected solid.
• DOMAIN : Select the target domain. This is a volume enclosed by the target domain(s). If the target domain is DOMAIN 3, type 3. If the target domain are DOMAIN 3 and DOMAIN 5, enter 3,5.
• ALL DOMAINS : The target volume is the whole simulation region

Point

• X,Y,Z : The position of the point.

Results returned

• FIELDS
  • E: Electric field data as a function of position and frequency/wavelength. Separate electric field components Ex, Ey and Ez are available.
  • H: Magnetic field data as a function of position and frequency/wavelength. Separate electric field components Ex, Ey and Ez are available.
  • S: Poynting vector as a function of position and frequency/wavelength. Separate electric field components Ex, Ey and Ez are available.
  • n (surface normals): Information about each element's surface normal in relation to x,y,z

• FLUX
  • SIGMA_FRONT, SIGMA_BACK - Cross section calculated as the dot product between Poynting vector and the normal vector integrated over the surface.
  • T_FRONT, T_BACK - Transmission through the monitor surface normalized to the source power. This dimensionless parameter is calculated only when the monitor is not closed surface.

For 2D monitors:

• RAWDGTDFIELDS:
  • E: Electric field as a function of components (x,y,z), frequencies, elements, and DG nodes.
  • H: Electric field as a function of components (x,y,z), frequencies, elements, and DG nodes.
• RAWDGTDMESH:
  • vertices: Mesh vertex coordinates given in Cartesian coordinates (x,y,z).
  • connectivity: Matrix connecting each 2D mesh element (each row) to its respective vertices.
  • order: Polynomial order.

The fields rawDgtdFields and rawDgtdMesh are relevant to the modeoverlap and modeexpansion script command.