MOM 6.2.10

15.11.1. Example 1: Design and analyze a corrugated horn in the band from 10 to 20 GHz.

his case explains how to calculate far-field, radiation pattern, current density, charge density and near field of a corrugated horn.


Step 1: Create a new MOM Project.


Open 'New Fasant' and select 'File --> New' option.


Figure: New Project panel


Select MOM option on the previous figure and start to configure the project.


Step 2: Change the scale to millimeters


Figure: Scale settings


Step 3: Create the geometry of the corrugated horn


Execute the function “corrugated_horn(fmin,fmax)”, which can be downloaded here.
To execute the function, click on Tools - Calculator and write the call to the function.


Figure: Calculator panel


The parameters to set are:


fmin: is the lowest operating frequency (GHz)
fmax: is the highest operating frequency (GHz)


The script file, called “script_corrugated_horn.nfs”, will be automatically generated in the mydatafiles folder in the newFASANT directory.


The next step is to execute the generated script file. For that, click on Tools – Script - Load and open the script “script_corrugated_horn.nfs”.


Horn geometry has been generated.


Step 4: Set Simulation Parameters


Select 'Simulation --> Parameters' option on the menu bar and the following panel appears. Set the parameters as the next figure shows and save it.


Figure: Simulation Parameters panel

Step 5: Set the source parameters.


Select 'Source --> Dipole --> Dipole Antenna' option and set the parameters as show the next figure. Then save the parameters and the dipole appears.


Figure: Dipole Antenna panel


Select 2 electric dipoles and click on “Position”.


Figure: Electric Dipole 1 Settings



Figure: Electric Dipole 2 Settings

Step 6: Set the solver parameters.


Click on Solver --> Parameters option on the menu bar. Verify that all the parameters are defined by default, as shown in next figure. Click on Save button before going to next step.


Figure: Solver panel


Select ‘Advanced Options’ and activate Preconditioner as shown.


Figure: Preconditioner panel

Step 7: Meshing the geometry model.


Select 'Meshing --> Parameters' to open the meshing configuration panel and then set the parameters as show the next figure. In order to obtain the shortest possible time for meshing, it is recommended to run the process of meshing with the number of physical processors available to the machine.


Figure: Meshing panel

The user can choose between:

- octaves: an automatic frequency range per octave is performed, that depends on the Initial and Final frequency. The user can choose 1 frequency by an octave or several frequencies by an octave. The more frequencies per octave, the greater the precision

- all frequencies: a meshing by each frequency is built, so it is the more accurate option. This option will only be chosen when the user needs a very accurate mesh.

Step 8: Execute the simulation.


Select 'Calculate --> Execute' option to open simulation parameters. Then select the number of processors as the next figure show. In order to obtain the shortest possible time for calculating the results, it is recommended to run the process with the number of physical processors available to the machine.


Figure: Execute panel


Then click on 'Execute' button to starting the simulation.

Step 9: Show Results.

To get more information about the graphics panel advanced options (clicking on right button of the mouse over the panel) see Annex 1: Graphics Advanced Options on GUI User Guide.

Select 'Show Results --> Far Field --> View Cuts' option to show the cuts of the observation directions options.

Far Field cuts. Corrugated Horn Antenna

Figure: Far Field cuts - Linear Amplitude

Selecting other values for the component, step, frequency or cut parameters and clicking on 'Add Series' button a new cut will be added to the selected parameters.

On 'Show Results --> Far Field' menu, other results are present such as 'View Cuts by Step' and 'View Cuts by Frequency' and this option display the values for one selected point for each step or frequency.

On 'Show Results --> Radiation Pattern' menu, other results are present such as 'View Cuts by Step' and 'View Cuts by Frequency' and this option display the values for one selected point for each step or frequency.

 

Select 'Show Results --> Radiation Pattern --> View 3D Pattern' option to show the cuts of the radiation pattern options.

Figure: Radiation Pattern 3D

Changing values for step, frequency, component or filtering parameters the visualization for the new parameters will be shown.

 

Select 'Show Results --> View Currents' option to show the current density.

Current Distribution. Corrugated Horn Antenna

Figure: Current Density

Changing values for step, frequency, magnitude, component or filtering parameters the visualization for the new parameters will be shown.

 

Select 'Show Results --> View Charges' option to show the charge density.

Charge. Corrugated Horn Antenna

Figure: Charge Density

 Changing values for step, frequency, magnitude or filtering parameters the visualization for the new parameters will be shown.

On 'Show Results --> Far Field' menu, other results are present such as 'View Cuts by Step' and 'View Cuts by Frequency' and this option display the values for one selected point for each step or frequency.

15.11.2. Example 2: Design and analyze a conical corrugated horn at 10GHz and 22 dB gain.

This case explains how to calculate far-field, radiation pattern, current density, charge density and near field of a corrugated horn with 22 dB gain at 10 GHz.


Step 1: Create a new MOM Project.


Open 'New Fasant' and select 'File --> New' option.


Figure: New Project panel


Select MOM option on the previous figure and start to configure the project.


Step 2: Change the scale to millimeters


Figure: Scale settings


Step 3: Create the geometry of the corrugated horn


Execute the function “corrugated_horn_gain(fmin,fmax,alfa,D)”, which can be downloaded here.
To execute the function, click on Tools - Calculator and write the call to the function.


Figure: Calculator panel


The parameters to set are:


fmin: is the lowest operating frequency (GHz)
fmax: is the highest operating frequency (GHz)
alfa: is the flare angle (obtained from the following graph)
D: is the aperture diameter (obtained from the following graph)

In this case, we will simulate at 10 GHz, so the maximum and minimum frequency are 10 GHz.

To choose the flare angle and the aperture diameter, observe the next graph.

 

For a gain of 20 dB a flare angle of 15 ° and a diameter of 5.5 times, λc is chosen. So:
Alpha = 15
D = 5.5


The script file, called “script_corrugated_horn_gain.nfs”, will be automatically generated in the mydatafiles folder in the newFASANT directory.


The next step is to execute the generated script file. For that, click on Tools – Script - Load and open the script "script_corrugated_horn_gain.nfs".


Horn geometry has been generated.


Step 4: Set Simulation Parameters


Select 'Simulation --> Parameters' option on the menu bar and the following panel appears. Set the parameters as the next figure shows and save it.


Figure: Simulation Parameters panel

Step 5: Set the source parameters.


Select 'Source --> Dipole --> Dipole Antenna' option and set the parameters as show the next figure. Then save the parameters and the dipole appears.


Figure: Dipole Antenna panel


Select 2 electric dipoles and click on “Position”.


Figure: Electric Dipole 1 Settings



Figure: Electric Dipole 2 Settings

Step 6: Set the solver parameters.

Click on Solver --> Parameters option on the menu bar. Verify that all the parameters are defined by default, as shown in next figure. Click on Save button before going to next step.


Figure: Solver panel


Select ‘Advanced Options’ and activate Preconditioner as shown.


Figure: Preconditioner panel

Step 7: Meshing the geometry model.


Select 'Meshing --> Parameters' to open the meshing configuration panel and then set the parameters as show the next figure. In order to obtain the shortest possible time for meshing, it is recommended to run the process of meshing with the number of physical processors available to the machine.


Figure: Meshing panel

Step 8: Execute the simulation.


Select 'Calculate --> Execute' option to open simulation parameters. Then select the number of processors as the next figure show. In order to obtain the shortest possible time for calculating the results, it is recommended to run the process with the number of physical processors available to the machine.


Figure: Execute panel


Then click on 'Execute' button to starting the simulation.

Step 9: Show Results.

To get more information about the graphics panel advanced options (clicking on right button of the mouse over the panel) see Annex 1: Graphics Advanced Options on GUI User Guide.

Select 'Show Results --> Far Field --> View Cuts' option to show the cuts of the observation directions options.

 

Figure: Far Field cuts - Linear Amplitude

 

Figure: Far Field cuts - Polar Amplitude

Selecting other values for the component, step, frequency or cut parameters and clicking on 'Add Series' button a new cut will be added to the selected parameters.

On 'Show Results --> Far Field' menu, other results are present such as 'View Cuts by Step' and 'View Cuts by Frequency' and this option display the values for one selected point for each step or frequency.

 

Select 'Show Results --> Radiation Pattern --> View Cuts' option to show the cuts of the radiation pattern options.

 

Figure: Radiation Pattern cuts

Selecting other values for the component, step, frequency or cut parameters and clicking on 'Add Series' button a new cut will be added to the selected parameters.

On 'Show Results --> Radiation Pattern' menu, other results are present such as 'View Cuts by Step' and 'View Cuts by Frequency' and this option display the values for one selected point for each step or frequency.

 

Select 'Show Results --> Radiation Pattern --> View 3D Pattern' option to show the cuts of the radiation pattern options.

 

Figure: Radiation Pattern 3D

Changing values for step, frequency, component or filtering parameters the visualization for the new parameters will be shown.

 

Select 'Show Results --> View Currents' option to show the current density.

 

Figure: Current Density

Changing values for step, frequency, magnitude, component or filtering parameters the visualization for the new parameters will be shown.

 

Select 'Show Results --> View Charges' option to show the charge density.

 

Figure: Charge Density

 

Changing values for step, frequency, magnitude or filtering parameters the visualization for the new parameters will be shown.

On 'Show Results --> Far Field' menu, other results are present such as 'View Cuts by Step' and 'View Cuts by Frequency' and this option display the values for one selected point for each step or frequency.

 

15.11.3. Example 3: Design of a corrugated horn with a customized profile.

This case explains how to add a new profile of the corrugated horn.

 

Step 1: Create a new MOM Project.

Open 'New Fasant' and select 'File --> New' option.

Figure: New Project panel

Select 'MOM' option on the previous figure and start to configure the project.

Step 2: Open the function

Select 'Tools --> User Functions' option on the menu bar and open the function "corrugated_horn.java" or "corrugated_horn_gain.java".

Figure: User Functions panel

Look for the 'try' exception and the IF ... ELSE IF statement with the "profile_index" parameter in the section 'Corrugated surface profile formulations':

Figure: Exception 'try' and if...else statement

The last 2 profiles (profile_index==8 and profile_index==9) are reserved for the user profile formulation. User profile 1 and User profile 2.

Step 3: Introduce the profile formulation

In this example, we will establish a linear profile in user profile 1 (profile_index==8). 

The linear profile has the following formulation:

Figure: Linear profile formulation

where:

  ai: input radius

  ao: output radius

  L: length

  z: in the variable parameter. It is necessary to enter it as i*p

We look for the 'User profile1' within the function:

Figure: User profile 1 and 2

And write our function, which in this case is the linear profile: 

az[i]=ai+(ao-ai)*(i*p/L);

Notes that 'z' has been changed to 'i*p'

 

Step 4: Select the user profile 1

To activate the profile entered, we have to select it within 'Profile Type Parameters' at the beginning of the function. In this case we select the profile index number 8 (profile_index = 8;)

Figure: Select the profile index

Step 5: Save the function

Finally, save the changes. Save it clicking on 'SAVE' or 'SAVE ALL' button.

Figure: Save the function

Step 6: Show Results

The corrugated horn with linear profile has been generated.

To simulate it, follow examples 15.12.1 or 15.12.2, depending on the user function where the new profile has been established.

 

15.11.4. Example 4: Compute the S-Parameters of a corrugated horn in the band from 10 to 20 GHz.

This case explains how to calculate S-parameters of a corrugated horn.


Step 1: Create a new MOM Project.


Open 'New Fasant' and select 'File --> New' option.


Figure: New Project panel


Select MOM option on the previous figure and start to configure the project.


Step 2Change the scale to millimeters


Figure: Scale settings


Step 3Create the geometry of the corrugated horn


Execute the function “corrugated_horn(fmin,fmax)”, which can be downloaded here.
To execute the function, click on Tools - Calculator and write the call to the function.


Figure: Calculator panel


The parameters to set are:


fmin: is the lowest operating frequency (GHz)
fmax: is the highest operating frequency (GHz)


The script file, called “script_corrugated_horn.nfs”, will be automatically generated in the mydatafiles folder in the newFASANT directory.


The next step is to execute the generated script file. For that, click on Tools – Script - Load and open the script “script_corrugated_horn.nfs”.


Horn geometry has been generated.


Step 4Set Simulation Parameters


Select 'Simulation --> Parameters' option on the menu bar and the following panel appears. Set a Frequency Sweep and the S-Parameters Simulation type as shown in the figure below. Remember clicking on Save button to confirm the changes.

 

Step 5Set the source parameters.

Note: this option requires that the geometry must be only one object (use the group command if it is not) and the waveguide cap needs to be removed

To add a waveguide port, select the object and click on 'Source' --> 'Waveguides' --> 'Add Waveguides Port' menu to open the panel.

And follow the steps describes on Add Waveguide Port


Step 6Set the solver parameters.


Click on Solver --> Parameters option on the menu bar. Verify that all the parameters are defined by default, as shown in next figure. Click on Save button before going to next step.


Figure: Solver panel


Select ‘Advanced Options’ and activate Preconditioner as shown.


Figure: Preconditioner panel

Step 7Meshing the geometry model.


Select 'Meshing --> Parameters' to open the meshing configuration panel and then set the parameters as show the next figure. In order to obtain the shortest possible time for meshing, it is recommended to run the process of meshing with the number of physical processors available to the machine.


Figure: Meshing panel

The user can choose between:

- octaves: an automatic frequency range per octave is performed, that depends on the Initial and Final frequency. The user can choose 1 frequency by an octave or several frequencies by an octave. The more frequencies per octave, the greater the precision

- all frequencies: a meshing by each frequency is built, so it is the more accurate option. This option will only be chosen when the user needs a very accurate mesh.

Step 8Execute the simulation.


Select 'Calculate --> Execute' option to open simulation parameters. Then select the number of processors as the next figure show. In order to obtain the shortest possible time for calculating the results, it is recommended to run the process with the number of physical processors available to the machine.


Figure: Execute panel


Then click on 'Execute' button to starting the simulation.

Step 9: Show Results.

To get more information about the graphics panel advanced options (clicking on right button of the mouse over the panel) see Annex 1: Graphics Advanced Options on GUI User Guide.

 

When the simulation process has finished, the S-Parameters are enabled within the results menu. Click on Show Results menu and S-Parameters option to visualize these parameters. The panel with the available options to visualize the S-Parameters is open on the right side.

Figure: S-Parameters parameters

Select the S-Matrix Representation and the option db, Phase in Representation section. Then, select the column to represent in the Results table and then click on Chart button to add them to plot them.

Figure: S11parameters plot

Figure: S11 parameters table

 

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