Example 4: 16x16 Short Dipole Array with Dolph-Chebychev Algorithm

This case explains how to use the Dolph-Chebychev algorithms to calculates the pointing parameters in a bidimensional short dipole array.

Step 1 Create a new MoM Project.

Open newFASANT and select File - New option.

Figure 1. New Project panel


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

Step 2 Set the simulation parameters as shown.

Select Simulation - Parameters option, set the parameters and save it.

Figure 2. Simulation panel


Step 3 Create the array.

Click on Source - Dipole - Dipole Array to create an array of 16x16 electrical short dipoles, with a spacing of 0.04 m, that are oriented following the y-axis. The array is located on the XY plane. The spacing of 0.04m is equivalent to a spacing of 0.267 in units of lambda, at a frequency of 2 GHz.

Figure 3. Dipole Array panel


Step 4 Feed the array.

To set the feeding of the array select Source - Antenna Feeding and the following panel will open.

Figure 4. Antenna Feeding panel


This is the default setting. To use the Dolph-Chebychev algorithm click on Tools - User Function and select the corresponding function. NOTE: To use the bidimensional Dolph-Chebychev function it is needed to download both the bidimensional and the unidimensional functions.

Figure 5. Bidimensional Dolph-Chebychev function


A path has been selected by default so the files will be created on the mydatafiles folder in the newFASANT directory.

Figure 6. Bidimensional Dolph-Chebychev function


The next step is generating the text file. To do so click on Tools - Calculator and write the call to the function.

Figure 7. Calculator panel


The parameters to set are:
  • d1: element spacing of the array in the x axis in units of lambda
  • N1: number of array elements of the array in the x axis
  • R1: relative side lobe level (in dB) in the x array
  • d2: element spacing of the array in the y axis in units of lambda
  • N2: number of array elements of the array in the y axis
  • R2: relative side lobe level (in dB) in the y array
  • theta: beam angle, in degrees
  • phi: azimuth angle, in degrees

In this case, set the parameters as shown. Angles of theta=45º and phi=0º, and a side lobe level of 50dB, are selected as an example.

Figure 8. Calculator panel


The text file will be automatically generated in the mydatafiles folder.

Figure 9. Results file


Now, apply these results to the array created before by clicking on Source - Antenna Feeding.

The panel shown before will appear. To use the weights and phases calculated with the Dolph-Chebychev algorithm, click on Import.

Figure 10. Amplitude/Phase File panel


Select the corresponding file and save the feeding.

Step 5 Create ground plane.

In order to avoid unwanted radiation to go below the array, create a ground plane using the plane command, or Geometry - Surface - Plane. The array is situated in the XY plane with z=0, so the z coordinate has to be negative.

Figure 11. Plane parameters


View of the dipole array.

Figure 12. Array view


Step 6 Solver parameters.

Select Solver - Advanced Options and set the parameters as shown.

Figure 13. Solver Advanced Options panel


Step 7 Meshing the geometry model.

Select Mesh - Create Mesh to open the meshing configuration panel and then set the parameters as show the next figure.

Figure 14. Meshing panel


Click on Mesh.

Step 8 Execute the simulation.

Select Calculate - Execute option to open simulation panel.

Figure 15. Calculate panel


Step 9 Show Results.

The radiation cuts can be visualized by clicking on Show Results - Radiation Pattern - View Cuts.

Figure 16. Radiation Pattern Cuts


Note that the side lobe level selected earlier must be represented here.

The radiation pattern can be visualized by clicking on Show Results - Radiation Pattern - View 3D Pattern.

Figure 17. Radiation Pattern 3D


Figure 18. Radiation Pattern 3D