* Right click on the '''Short Dipoles''' item in the '''Sources''' section of the Navigation Tree and select '''Insert New Source...''' from the contextual menu. The Short Dipole dialog opens up.
* In the '''Source Location''' section of the dialog, you can set the coordinate of the center of the short dipole. By default, the source is placed at the origin of the world coordinate system at (0,0,0). * * In the '''Source Properties''' section, you can specify the '''Amplitude''' in Amp, the '''Phase''' in degrees as well as the '''Length''' of the dipole in project units.
* In the '''Direction Unit Vector''' section, you can specify the orientation of the short dipole by setting values for the components '''uX''', '''uY''', and '''uZ''' of the dipole's unit vector. The default values correspond to a vertical (Z-directed) short dipole. The dialog normalizes the vector components upon closure even if total radiated power by your component values do not satisfy a unit magnitudedipole source is calculated and displayed in Watts in the dialog.
=== Plane Wave Sources ===
[[File:PO29.png|thumb|300px|PO Module's Plane Wave dialog]]
Your physical structure in [[PO Module]] EM.Illumina can be excited by an incident plane wave. In particular, a plane wave source can be used is needed to compute the radar cross section of a target. A plane wave is defined by its propagation vector indicating the direction of incidence and its polarization. [[EM.Cube]]'s [[PO Module]] Illumina provides the following polarization options: TMz, TEz, Custom Linear, LCPz and RCPz.
The direction of incidence is defined through the θ and φ angles of the unit propagation vector in the spherical coordinate system. The values of these angles are set in degrees in the boxes labeled '''Theta''' and '''Phi'''. The default values are θ = 180° and φ = 0° representing a normally incident plane wave propagating along the -Z direction with a +X-polarized E-vector. In the TM<sub>z</sub> and TE<sub>z</sub> polarization cases, the magnetic and electric fields are parallel to the XY plane, respectively. The components of the unit propagation vector and normalized E- and H-field vectors are displayed in the dialog. In the more general case of custom linear polarization, besides the incidence angles, you have to enter the components of the unit electric '''Field Vector'''. However, two requirements must be satisfied: '''ê . ê''' = 1 and '''ê × k''' = 0 . This can be enforced using the '''Validate''' button at the bottom of the dialog. If these conditions are not met, an error message is generatedpops up. The left-hand (LCP) and right-hand (RCP) circular polarization cases are restricted to the normal incidences incidence only (θ = 180°).
To define a plane wave source follow these steps:
* Right click on the '''Plane Waves''' item in the '''Sources''' section of the Navigation Tree and select '''Insert New Source...''' The Plane wave Dialog opens up.
* In the Field Definition section of the dialog, you can enter the '''Amplitude''' of the incident electric field in V/m and its '''Phase''' in degrees. The default field Amplitude is 1 V/m with a zero Phase.
* The direction of the Plane Wave is determined by the incident '''Theta''' and '''Phi''' angles in degrees. You can also set the '''Polarization''' of the plane wave and choose from the five options described earlier. When * If the '''Custom Linear''' option is selected, you also need to enter the X, Y, Z components of the '''E-Field Vector'''.
=== Huygens Sources ===