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  Radiated Fields Post Processing   

Computing Antenna Parameters

You must have defined at least one radiation or PML boundary in the design for HFSS to compute antenna parameters and maximum field data for the far-field region. You can Export the calculated antenna parameters and maximum field data to a file. You can also Export Fields in the .csv format. This can be useful for situations when want to share the fields without sharing the model geometry.

1. To select the radiation setup from the Project tree, right-click the Infinite Sphere icon in the project tree under Radiation, and then click Compute Antenna Parameters on the shortcut menu.

Or, to select the radiation setup from a dialog, click HFSS or HFSS-IE>Radiation>Compute Antenna Max/Params.

The Select Radiation Setup dialog appears.

After you have selected the setup by one of these two methods. the Antenna Parameters dialog box appears.

2. Under the Solutions tab, select the solution for which you want HFSS to compute antenna parameters.

3. Under the Intrinsic Variables tab, select the solved frequency point at which you want HFSS to compute antenna parameters.

The Antenna Parameters window appears. If the design includes ports, the following antenna parameters are listed:

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Maximum intensity (Max U)

 

Peak directivity

 

Peak gain

 

Peak realized gain

 

Radiated power

 

Accepted power

 

Incident power

 

Radiation efficiency

 

Front to Back Ratio

 

Decay Factor

 

Warning

The computed values of max U and peak directivity depend on the user-determined set of aspect angles chosen for the computation of the radiated fields. If this set does not encompass the actual peak intensity of the radiated pattern, the displayed results for these three parameters will be inaccurate.

Note

Accepted Power is computed from the raw S-parameter data. Post-processing operations are excluded from the calculation, for example, renormalized S-parameters.

Note

It is important to understand the impact of passive ports (for Transient Network designs or models containing an Array with passive ports) on antenna parameters. For accepted power calculations, passive ports are not included when computing the total power passing through the union of all port surfaces. This means that the passive ports can be viewed as a loss mechanism for the device and it is not equivalent to viewing the passive ports as active ports with zero excitations.

Gain and realized gain are very close to each other when the antenna is matched. However, for designs with a multi-port antenna, gain and realized gain can be different if incident and accepted power are different. There can be a small reflection at the ports and accepted power may still be small if energy injected in one port exits the model through a different port. A review of the S-matrix can show this to be the case. This does not happen in a single port antenna, which is what most users base their expectations on.

If the design does not have ports, the following antenna parameters are listed:

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Maximum intensity (Max U)

 

Peak directivity

 

Radiated power

 

4. Click More to view the following maximum far-field data:

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Total

 

X

 

Y

 

Z

 

Phi

 

Theta

 

LHCP

 

RHCP

 

Ludwig 3/X dominant

 

Ludwig 3/Y dominant

 

Note

When calculating the maximum far-field values, the distance r is factored out of the E-field. Therefore, the units for the maximum field data values are given in volts.

Related Topics

Radiated Fields Post Processing

Exporting Antenna Parameters and Maximum Field Data

Technical Notes: Antenna Parameters

Technical Notes: Maximum Far-Field Data

Add Trace Characteristics