button in Radiation tab and Antenna Settings->2D Chart… command from main menu or context menu invoke Radiation Patterns dialogue for changing 2D radiation pattern parameters.2.18.7 Radiation Patterns
The button in Radiation tab and Antenna Settings->2D Chart… command from main menu or context menu invoke Radiation Patterns dialogue for changing 2D radiation pattern parameters.
The far field patterns will be calculated in a spherical coordinate system with one Reference Axis and two angles: elevation (Theta) and azimuthal (Phi). The picture on the right side of the dialogue reminds the sense of Theta and Phi (in the first of above figures in case when the Reference Axis is Z). If another Cartesian axis (X or Y) is chosen as the Reference Axis the below picture will change accordingly.
In QW-V2D the only available reference axis is X (the axis of rotation):
A rare feature of QW-3D resides in allowing a so-called arbitrary Axis Z’, of any orientation in space. Precisely speaking, the original XYZ coordinate system will be transformed as follows:
· first, it is translated so that the origin is located at Reference Point,
· then it is rotated using Euler Angles defined in the lower part of the dialogue
The position of the Reference Point does not influence the absolute values of the far field radiation patterns (in lossless NTF background medium) but it does influence their phase characteristics. A possibility of modification of the Reference Point coordinates facilitates searching for a phase centre of the antenna.
As regards the meaning of the Euler Angles, several conventions can be found in the literature, and the following one has been adopted in QuickWave software:
· First the coordinate system is rotated clockwise around the original Z-axis, by precession angle Alfa (0 £ Alfa £ 360). This keeps the Z-axis unchanged while the X- and Y-axes are rotated in the XY-plane, becoming intermediate axes Xint and Yint.
· Then the intermediate coordinate system is rotated clockwise around the intermediate Yint-axis, by nutation angle Beta (0 £ Beta £ 180). This keeps the intermediate Yin axis unchanged while the original Z and intermediate Xint axis are rotated in the XintZ-plane. This produces the new Z’ axis and the second-intermediate Xint2.
· Finally the second intermediate coordinate system is rotated clockwise around the new Z’-axis, by rotation angle Gamma (0 £ Gamma £ 360). This produces the new X’ and Y’ axes.
For the avoidance of doubt, the versors of the new axes X’, Y’ and Z’ in the old XYZ coordinates are calculated by the software and displayed in the lower right part of the Radiation Patterns dialogue, in its first, second and third rows, respectively.
The radiation pattern will be calculated in the new X’Y’Z’ coordinate system, with reference axis Z’, and Phi angle calculated from X’ clockwise.
The Versus frame allows choosing between radiation patterns calculated:
· with respect to Theta angle (with constant Phi as well as Theta step, starting value and end value set in the For frame),
· with respect to Phi angle (with constant Theta as well as Phi step, starting value and end value set in the For frame).
Use NTF samples indicates which NTF samples will be taken into account during radiation pattern calculation. Settings button opens the Use NTF samples dialogue for setting the sparsity for NTF samples.
Number of ground planes is active only if one, two, or three electric or magnetic walls have been detected by the software at any of the NTF walls. QW-Simulator will then perform NTF calculations with Green’s functions appropriate for the resulting half- quarter- or one-eights of space. Note that there is ambiguity in gain calculations between two scenarios such as: one dipole radiation over a physical ground plane or a system of two dipoles in free space, a half of which is simulated with a symmetry plane. These two scenarios are identically defined from the viewpoint of the simulated geometry but physically they differ by 3 dB in gain and efficiency values. The second case (free space with symmetry planes) is default in the software, however, the user may direct the software and set the number of physical ground planes present in the scenario for correct gain and efficiency values calculation. This is done with Number of ground planes option. Refer to User Guide 3D: One dipole near electric wall for examples.
Gain References allows choosing between: directive gain, power gain, absolute_1port gain, absolute gain, and Fields at 1m scaling. For detailed discussion regarding gain scaling refer to Antenna Gain.
The software calculates total Radiated Power, which is displayed in the Results window denoted by Pr. It is a time-maximum power radiated and it is used for gain calculation: Directive, Power, Absolute_1port, and Absolute gain scaling options. By default, this power is obtained by Poynting vector integration over the NTF box which corresponds to Single Radiation Pattern option. Detailed discussion regarding the radiated power calculation is given in Radiated Power.
NTF Walls button opens the Pickup Walls dialogue for choosing the NTF walls.
See also 2D Radiation Pattern chapter for more information.
The NTF Walls… button in the Radiation Patterns dialogue opens the Pickup Walls dialogue.
By default, all six walls are checked and take part in NTF transformation in QW-3D; in QW-V2D three walls are automatically excluded.
The user may uncheck and exclude any combination of the walls from one NTF post-processing. A detailed discussion regarding this software feature and its application is given in Radiation pattern at chosen Huygens surface. An example of application is described in User Guide 3D: Disconnecting NTF walls.
The Settings… button in the Radiation Patterns and in the 3D Radiation Patterns dialogues open the Use NTF samples dialogue.
This dialogue allows setting the sparsity for NTF samples (which NTF samples will be taken into account during radiation pattern calculation).