A lumped source can only be placed on a line object. Additionally, the line must be parallel to one of the principal axes. The dropdown list labeled Line Object displays all the eligible lines in the project workspace. In this project, there is only one object, which is selected by default. A new lumped source is placed at the center of the host line object by default. The location of the source can be changed via the Offset parameter of the dialog. We will leave this at 75 for this tutorial, as we want to test a center-fed dipole. You can also change the direction of the lumped source.
[[Image:fdtd_lec1_12_lumpedsourcefig.png|400px300px|left]] Your lumped source will have an Amplitude of 1V and a zero Phase. This means that the voltage source will excite the dipole with a modulated Gaussian pulse waveform centered at 1GHz with a frequency bandwidth of 1GHz, where the envelope of the signal reaches a maximum voltage of 1V. You will see the lumped source in the middle of the dipole, represented by an arrow pointing in the +Z direction.
==1.6 Grid Settings & Mesh Generation==
==1.7 Defining Project Observables==
[[Image:fdtd_lec1_15_fieldprobe.png|400px|right]] Project observables are output quantities that you would like to compute at the end of an FDTD simulation. By default, an FDTD time marching scheme does not generate any output data unless you define one or more project observables before you start a simulation.
[[Image:fdtd_lec1_16_fieldsensor.png|right]] Field Probes
The simplest observable is a Field Probe, which is used to record the field values as a function of time at a specific point inside the computational domain. To define a field probe, right click on the Field Probes item in the âObservablesâ section of the navigation Tree and selec Insert New Observable⦠In the Field Probe Dialog, select X from the dropdown list labeled Direction. This means that your probe will record the X component of electric and magnetic fields. Enter the point (5, 5, 75) as the Coordinates of the field probe. Click the OK button of the dialog to accept the changes
[[Image:fdtd_lec1_16_fieldsensor.png|400px|right]] Field Sensors
[[Image:fdtd_lec1_16_fieldsensor.png|400px|left]] Field sensors are are used to visualize the near fields of your structure on a plane parallel to one of the three principal planes. The field sensor planes extend across the entire computational domain. To define a field sensor, right click on the Field Sensors item in the âObservablesâ section of the Navigation Tree and select Insert New Observable⦠In the Field Sensor Dialog, enter the point (0, 0, 0) for Coordinates and select X from the dropdown list labeled Direction. This means that your field sensor plane will be the YZ plane, which passes through the dipole antenna. We would like to display the fields in the frequency domain at 1GHz. Accept the other default settings in the dialog box, and select OK to continue. A new entry Sensor_1 is added to the Navigation Tree, and the field sensor is now represented in the project workspace by a purple plane across the computational domain.