GTD 6.2.9

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11.3. Near Field

Using this menu it is possible to analyze the amplitudes in the Near Field through the observation directions previously defined in the Output section.

The following options are available:

  • View Cuts: display a plot that relates the amplitude against the observation cut.
  • View Cuts by Frequency: displays a plot that relates the amplitude against a frequency sweep.
  • View Cuts by Step: displays a plot that relates the amplitude against a parametric step.
  • Near Field: displays the numeric results using a colored map.
  • Delay Process: displays the results of the delay process.
  • Power Process: displays the results of the power process.

 

Show Results menu with a near field simulation

 

 

11.3.1. View cuts

This command plots the amplitude and phase of the near field computed for each observation point of the simulation geometry. Several observation points (such us lines, planes and so on) and frequencies can be plotted in the same graphic. To plot a graph, the user can select the field component, the step, the frequency, the observation, the order and the antenna. A new graph will be plotted with the button 'Add Series'. In the case that the user has set up a parametrized geometry (see the Geometry User Guide for details), it is possible to select the step to visualize the results for.

It is also possible to delete a series that is selected by the user from the list with the 'Remove Series'. The display option also allows changing the color of the series and display points. The buttons 'Import Series' and 'Export Series' are used for importing and exporting the selected series in 'List of Series' to a text file.

This panel displays a plot with the results and several options for adding and removing extra series from the plot.

When initially open, the panel will display a default series in the plot that will represent the measurements for a particular component, step, frequency, and observation point, against every possible frequency that has been simulated. More series can be added, by selecting a component, step, observation, order and antenna in the control panel that appears on the left side of the plot.

  • Component: the field component to inspect. Select one of the possible values: Ex, Ey, Ez, Etotal.
  • Step: the parametric step to select. These should have been defined prior to the calculation when designing the simulation.
  • Frequency: select one frequency to inspect.
  • Observation: select one of the observation series.
  • Order: select a particular order.
  • Antenna: select a particular antenna.

 

Near Field View Cuts panel

 

 

 

11.3.2. View cuts by frequency

This kind of plot can be used to compare the amplitude measurements made by the simulation process for a particular component, step, observation point, order and antenna, against a simulation frequency. This option is useful when the user has selected a frequency sweep in the Simulation Settings, in order to inspect how the measurements for a particular observation point change through a frequency sweep.

When this option is chosen from the Show Results > Near Field > View Cuts By Frequency menu, the panel presented in the figure below will appear.

 

View cuts by frequency panel

 

Similar to the behavior of the standard Far Field chart, this panel displays a plot with the results and several options for adding and removing extra series from the plot.

When initially open, the panel will display a default series in the plot that will represent the measurements for a particular component, step, frequency, and observation point, against every possible frequency that has been simulated. More series can be added, by selecting a component, step, observation, order and antenna in the control panel that appears on the left side of the plot.

  • Component: the field component to inspect. Select one of the possible values: Ex, Ey, Ez, Etotal.
  • Step: the parametric step to select. These should have been defined prior to the calculation when designing the simulation.
  • Observation: select one of the observation series.
  • Point: select the observation point.
  • Order: select a particular order.
  • Antenna: select a particular antenna.

The selected series can be added to the plot by pressing the Add Series button. It is also possible to modify the look and delete series previously added to the chart. You can change the color of a particular series by selecting it in the list and pressing the Change Colors. To remove a series from the plot representation, click on the Remove series button.

Series can be imported and exported. To save a series click on the Export series button. Later it is possible to load previously exported series by pressing the Import Series button and locating the file where the results were saved in.

 

11.3.3. View cuts by step

This kind of plot lets the user analyze RCS measurements made by the simulation process for a particular component, frequency, theta or phi cut and observation point against the parametric steps defined in the project. This option is useful when the user has parametrized a simulation by adding parameters and making objects such as geometries depend on the parameters themselves.

When this option is chosen from the Show Results > Far Field > View Cuts by Steps menu, the panel presented below will appear:

 

View cuts by step panel

Similar to the behaviour of the standard Far Field chart, this panel displays a plot with the results, and several options for adding and removing extra series from the plot.

When initially open, the panel will display a default series in the plot that will represent the measurements for a particular component, step, frequency, and observation point, against every possible frequency that has been simulated. More series can be added, by selecting component, step, observation, order and antenna in the control panel that appears leftside to the plot.

  • Component: the field component to inspect. Select one of the possible values: Ex, Ey, Ez, Etotal.
  • Frequency: select one frequency to inspect.
  • Observation: select one of the observation series.
  • Point: select one of the observation points.
  • Order: select a particular order.
  • Antenna: select a particular antenna.

The selected series can be added to the plot by pressing the Add Series button. It is also possible to modify the look and delete series previously added to the chart. You can change the color of a particular series by selecting it in the list and pressing the Change Colors. To remove a series from the plot representation, click on the Remove series button.

Series can be imported and exported. To save a series click on the Export series button. Later it is possible to load previously exported series by pressing the Import Series button and locating the file where the results were saved in.

 

 

11.3.4. Near field

When this option is selected, the following panel will appear:

 

Near field panel

 

In this panel, the user can select a step, a frequency (from the set of sampled frequencies) and a set of observation points (holding the Ctrl key, the user can select more than one item from the list). When the user presses the OK button, the following window will be opened, showing a 3D diagram of the near field values on the selected observation points:

 

3D diagram showing the near field values.

 

When initially open, the panel will display a default series in the plot that will represent the measurements for a particular component and field in dBo natural magnitude. Different values can be visualized by changing the parameters in the control panel.

  • Incidence: the type of field to inspect. Select one of the possible values: Direct, Scatter, Total.
  • Magnitude: dB o natural.
  • Component: the field component to inspect. Select one of the possible values: Ex, Ey, Ez, Etotal.
  • Filter: enable the filter checkbox and select a particular maximum and minimum to filter the values that will be plotted.

 

 

 

11.3.5. Delay process

The Delay Process is a post-process computation that shows how a given signal is distorted in the time domain because of its environment. The signal, which may be set with different shapes, is generated by every antenna source available in the simulation, and the delay process may be computed in multiple near field observation poins.

After running a Delay Process type simulation, click on Show Results - View Delay Process to open the Delay Process window, and the following panel is shown on the right side:

 

Delay process configuration panel

 

 

This panel contains several options for plotting the Delay Process:

  • Component: specify the component considered for the Delay Process computation (Ex, Ey or Ez).
  • Selection: to define the spherical far-field ranges where the Delay Process will be computed. The first row defines the theta interval and the second row the phi one.
    • Step: select the step of the parametris simulation to be consider. If it is not a parametric simulation, this value will be 1.
    • Frequency: frequency of the simulation.
    • Point: select the observation pont index to consider in the Delay Process.
  • Signal: the original signal may be generated by using different patterns. All of them are configured in the time domain.
    • Dirac Delta: only a pulse is generated in the initial time.
    • CDMA: a random distribution of pulses centred with positive (high) an negative (low) levels is generated. Note that a low or high level is considered as a Pulse.
      • Length: number of pulses to be generated.
      • Pulse Width: time duration of each Pulse, in microseconds.
    • Sinusoid: a sinusoidal signal is generated.
      • Carrier Freq.: frequency of the sinusoidal signal, in MHz.
      • Phase: initial phase of the sinusoidal signal, in degrees.
      • Duration: total length of the generated sinusoid in the time domain, in microseconds.
    • Tukey Envelope: a gaussian signal enveloped by a rectangular pulse is generated.
      • Alpha Parameter: define the slope of the gaussian curve. The higher is this parameter, the more enveloped by the rectangular pulse is the generated signal.
      • Pulse Width: define the total length of the generated signal in the time domain, in microseconds.
  • Time: this section specifies the observation time range.
    • Initial: first observation instant in the time domain, in microseconds.
    • End: last observation instant in the time domain, in microseconds.
    • Samples: number of instants to evaluate de Delay Process that are equally equispaced in the time domain.

Click on OK button to plot de Delay Process results.

Only when the CDMA signal has been selected, the window represented below aks the selection of the Correlation Signal to be plottedwith the following options.

  • Input (x[n]): the original CDMA signal is represented.
  • Output (y[n]): the received CDMA signal is represented
  • Correlation (c[n]): the correlation on the received signal is represented.

chose a signal window

Selection of signal to be plotted with CDMA

 

Delay Process generated with a Dirac Delta signal

 

Delay Process generated with a CDMA (output y[n]) signal

Delay Process generated with a Sinusoid signal

 Delay Process generated with a Tukey Envelope signal

 

11.3.6. Power process

When this option is selected, the following panel will appear:

 

 Power process configuration panel

 

In this panel, the user can configure the component to be shown, the step, the frequency and the antenna to show the results for. Pressing the OK button will show the chart.

 

Power Process generated

 

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