Lumped Port
Use the Lumped Port node to apply a voltage or current excitation of a model or to connect to a circuit. A lumped port is a simplification of the port boundary condition.
A Lumped Port condition can only be applied on boundaries that extend between two metallic boundaries — that is, boundaries where Perfect Electric Conductor, Impedance Boundary, Transition Boundary, Layered Transition Boundary, or Cable Shield (Electromagnetic Waves, Frequency Domain interface only) conditions apply — separated by a distance much smaller than the wavelength.
Lumped Port Properties
Enter a unique Lumped port name. It is recommended to use a numeric name as it is used to define the elements of the S-parameter matrix and numeric port names are also required for port sweeps and Touchstone file export (for the Electromagnetic Waves, Frequency Domain interface).
Type of Lumped Port
Select a Type of lumped port — Coaxial, Multielement uniform, Reference-edge controlled, Uniform, User defined, or Via.
Select User defined for nonuniform ports, for example, a curved port and enter values or expressions in the fields — Height of lumped port hport (SI unit: m), Width of lumped port wport (SI unit: m), and Direction between lumped port terminals ah. In 2D axisymmetry, Coaxial does not support a nonzero azimuthal mode number. The Azimuthal mode number should be set to zero in the Out-of-Plane Wave Number section in the settings for The Electromagnetic Waves, Frequency Domain Interface. When it is modeled in 3D, its geometry has to be a full coaxial shape.
Notice that the input field for Direction between lumped port terminals ah is not shown in 2D, when Electric field components solved for is set to Out-of-plane vector in the Components section for the physics interface. In this case the Direction between lumped port terminals ah is defined to be in the out-of-plane direction.
 
A partial geometry can also be analyzed with proper symmetry conditions such as symmetry planes or perfect magnetic conductors on the cut boundaries parallel to the electric field polarization. However, if symmetry planes are not used, then the characteristic impedance needs to be adjusted proportionally to the ratio between the full and partial geometry areas. For instance, the user-specified characteristic impedance of a half coaxial cable should be twice that of the full geometry.
Select Multielement uniform for multiexcitation or termination of, for example, a coplanar waveguide port or a differential port. The direction of the field in each subelement of the Multielement uniform lumped port is defined by the subnodes, Uniform element.
Select Via for excitation or termination of a cylindrical shape of a structure used in a metalized via that is a plated through hole.
Select Reference-edge controlled to define the Direction between lumped port terminals ah. The selected edge represents the voltage drop line.
Terminal Type
Select a Terminal type — a Cable port for a voltage driven transmission line and S-parameter calculation, a Current driven port, or a Circuit port.
For Cable, select On or Off from the Wave excitation at this port list to set whether it is an inport (excitation) or a listener port (observation).
Settings
Source Type
If On is selected for the Wave excitation at this port, select Voltage or Power from the Source type. For the Voltage source type, enter a Voltage V0 (SI unit: V), and Port phase θin (SI unit: rad). For the Power source type, enter a Power P0 (SI unit: W) that is the average input power to the lumped port.
Note it is only possible to excite one Cable port at a time if the purpose is to compute S-parameters. In other cases, for example, when studying microwave heating, more than one inport might be wanted, but the S-parameter variables cannot be correctly computed so if several ports are excited, the S-parameter output is turned off.
For the Electromagnetic Waves, Frequency Domain and Microwave Heating interfaces, the Port Sweep Settings cycles through the ports, computes the entire S-matrix, and exports it to a Touchstone file. When using port sweeps, the local setting for Wave excitation at this port is overridden by the solver so only one port at a time is excited.
No entry is required if a Circuit terminal type is selected above.
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For a Cable terminal type enter the Characteristic impedance Zref (SI unit: Ω). When using a lumped port on a partial geometry combined with symmetry plane features, enter the value for the full geometry if the Characteristic impedance adjustment by symmetry plane check box is marked.
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For a Current terminal type enter a Terminal current I0 (SI unit: A).
Coaxial
The following figure shows an example of a boundary selection for a Coaxial lumped port in a 3D model.
Coaxial Line Impedance Calculator
Enter a Relative permittivity (default is 1) for the dielectric material between the coaxial inner and outer conductor and then click the Compute Coaxial Line Impedance button to compute the impedance for the coaxial lumped port. The result is displayed in the Messages window.
Multielement Uniform
The following figure shows an example of a boundary selection for a Multielement uniform lumped port in a 3D model.
Uniform
The following figure shows an example of a boundary selection for a Uniform lumped port in a 3D model.
Via
The following figure shows an example of a boundary selection for a Via lumped port in a 3D model.
Calculate S-parameter
The Calculate S-parameter check box needs to be selected for S-parameter calculation with the Electromagnetic Waves, Transient and Electromagnetic Waves, Time Explicit interfaces, while the Cable port in the Electromagnetic Wave, Frequency Domain calculates S-parameters automatically.
Voltage Source Type
When Calculate S-parameter is selected, select Voltage source type from the list (default Modulated Gaussian pulse). The Modulated Gaussian pulse is defined as
where the Center frequency f0 defines the location as 2/f0, the standard deviation as 1/(2f0), and the modulation frequency f0. ηf is the upshift ratio for the sinusoidal modulation frequency.
The modulating sinusoidal function can be slightly shifted from the center frequency f0 by a factor of 1 + ηf to improve the frequency responses.
Center Frequency
When Calculate S-parameter is selected, enter a Center frequency f0 for the input modulated Gaussian pulse (SI unit: Hz).
Modulation Frequency Upshift Ratio
When Calculate S-parameter is selected, enter a Modulation frequency upshift ratio ηf for the input modulated Gaussian pulse.
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S-Parameters and Ports
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Lumped Ports with Voltage Input
As a multiport device example, Branch-Line Coupler: Application Library path RF_Module/Couplers_and_Power_Dividers/branch_line_coupler
For example of how to use the Multielement uniform lumped port, Coplanar Waveguide Bandpass Filter: Application Library path RF_Module/Filters/cpw_bandpass_filter
Current Pulse Type
In the Electromagnetic Waves, Transient interface, when Terminal type is set to Current, select Current Pulse Type from User defined (the default), Electrostatic discharge, and Lightning.
Enter pulse model parameter values and click the Plot Pulse Shape button to inspect the current pulse instantly as a function of time before running a simulation.
Electrostatic Discharge Pulse Model
When Current Pulse Type is set to Electrostatic discharge, select Electrostatic Discharge Pulse Model from Human body model (the default), Extended human body model, Machine model, and Charged device model.
Electric Field Direction
To display this section, click the Show More Options button () and select Advanced Physics Options in the Show More Options dialog box. When the lumped port boundaries are parallel to one of the Cartesian coordinate planes, click the Plot Electric Field Direction button to inspect the electric field direction in the mode field instantly before running a simulation. Default mode field direction can also be switched to the opposite direction by selecting Reverse mode field direction.