Antenna Array Synthesis in Antenna Magus


Image of a Planar Antenna Array
Image of a Concentric Circular Antenna Array

Antenna Magus contains a wide collection of antenna array configurations .This application note discusses the Antenna Magus workflow for exploring and synthesizing these antenna arrays. We go through the typical workflow of designing an array for two different array configurations and then compare their results.

User Interface

If you are unfamiliar with Antenna Magus it is suggested that you briefly familiarize yourself with the main components of the user interface. A short application note on the basic layout of the user interface is available here.

Exploring the Arrays

To start the array design we have to add an array prototype to the 'Collection'. Do this by clicking on the 'Array Synthesis' button located on the 'Home' ribbon. Antenna Magus creates and opens a new array prototype and also starts a new design for the prototype. In the workspace we see a browsable collection of antenna array configurations. The layouts of the configurations are illustrated on the thumbnails with the orange arrows indicating some of the parameters that can be set. More information about each of these array configurations are also available on the antenna amagus website

Zoom
Zoom

We can also select a configuration by using the drop-down menus in the 'Pallet'.

Synthesise Planar Array

The first array that we will look at is a planar array with broadside directivity. In the 'Arrays' expander rename the design from "Array 1" to "Planar Array". In the 'Create Distribution Matrix' expander select 'planar' from the 'Choose Array Shape' drop-down.

Zoom

We are now presented with specific planar configurations in the 'Specify' drop-down. Select the '+ Exitation taper' option of the 'Broadside directivity or beamwidth' configuration.

Click on 'Set Up' to choose the specific configuration. In the 'Workspace' we are presented with additional information on this configuration.

Zoom

We are also presented with additional design options in the 'Create Distribution Matix' expander. Set the centre - and display frequency both to 30GHz. Choose 'Specify beamwidth' in the 'Main-beam' drop-down and set the value to 15 degrees in both the x and y direction. In the 'Taper' drop-down select 'All side lobes equal' and set the Side-lobe level to 30dBi. Click on 'Apply' after entering all the parameters.

Zoom

Antenna Magus will switch to the 'Array Layout' tab; here the Layout of the array as well as the Isotropic array pattern (where each element is a spherical radiator with 0 dBi gain in all directions) can be inspected. (Shown below)

Zoom

At the bottom of the 'Pallete' we see the 'Derived Parameters' expander. Here we note that the number of elements required for design objective is 64.

Zoom

To synthesise the array for a specific antenna element, we can specify a node on the 'Element Pattern' tab. Switch to this tab and select 'Left-hand circular QHA' from the drop-down. Select 'Z' from the 'D_max' drop-down and click on 'Apply'. The radiation pattern for the antenna is displayed in the workspace (shown below). This radiation pattern will be used as the element patterns in the synthesis of the array. Note that custom element patterns can also be imported.

Zoom

Navigate to the 'Synthesised Array' tab to view the results of the synthesised array (shown below).

Zoom

Synthesise Concentric Circular Array

Synthesizing the Concentric Circular Array is a similar process as that described above. Start a new array design by clicking 'New Array' in the 'Arrays' expander or in the 'Home' ribbon. Again the collection of array configurations is displayed in the workspace. In the 'Create Distribution Matrix' set the value for 'Choose Array Shape' to 'Concentric circular' and the value of 'Specify' to 'Beamwidth with a specific taper and steering angle'. Click on 'Set up' to select this configuration. Information for the selected configuration is displayed in the workspace.

Zoom

Additional input parameters are displayed in the 'Create Distribution Matrix' expander. Set values in the expander to the values shown in the image below and click on 'Apply'. We are designing for the same beamwidth and side-lobe level as the previous design.

Zoom

In the 'Workspace' the layout and isotropic radiation pattern is displayed. Note that the plot for both designs is shown

Zoom
Zoom

In the 'Derived Parameters' we note that the number of elements required (77) for this array is higher than for the planar array with similar design objectives. The physical size of the array is also slightly larger than for the planar array.

Navigate to the 'Element pattern' tab to set the node radiation pattern. Select 'Left-had-circular QHA' from the 'Choose Pattern' drop down; set 'D_max' to 'Z' and click on 'Apply'. The radiation pattern for the antenna is displayed in the workspace. This radiation pattern will be used in the synthesis of the array.

Navigate to the 'Synthesised Array ' to view the results. In the workspace we can compare the results of the two array configurations. Shown below is the XZ-plane cut of the radiation pattern of the two arrays. Note the similarity of the two plots.

Zoom

We can also compare the 3D synthesised array pattern by switching between the two designs in the 'Arrays' expander located in the 'Pallet '. Shown below are the two radiation patterns side by side. Here the difference between the radiation patterns of the two designs are more noticeable. The concentric circular array configuration results in a pattern which is symmetrical around the vertical axis with more evenly shaped sidelobes.

Zoom Zoom

Conclusion

We looked at the design and synthesis of two antenna array configurations. The configurations were compared by designing them both for similar objectives and then inspecting the synthesised results and noting the differences in physical attributes.We noted that the main beams of the two arrays were almost identical where the concentric circular array has a symmetrical pattern around the vertical axis with smoother sidelobe distribution compared to the square planar array.

Printable version