Push Excitations with Thevenin Equivalent

A Thevenin Equivalent is the efficiency and realized gain of an antenna in a circuit. The Thevenin Equivalent calculation is supported only with a LNA solution. To capture the loss of any intermediate circuitry (such as a matching circuit) the design needs to push incident power at the Circuit ports and push the Thevenin Equivalent at the HFSS ports. These values can be computed by HFSS.

A push excitation with a Thevenin Equivalent is configured through a dynamic link, with the complex impedance defined in the Circuit Tool and with the antenna defined as an HFSS dynamic-link sub-circuit.

• From the Push Excitation Information window, the Calculate Thevenin Impedance check box is cleared by default.
• Thevenin impedance values are calculated per pin and are pushed to HFSS when the check-box is selected. The impedance is 0 ohms for shorted pins and is inf ohms for open pins. These values are functions of frequency.
• For an HFSS discrete sweep, the push excitations, available power, and Thevenin impedances are at HFSS sweep frequencies. For all other cases, pushed data corresponds to frequency points on the Nexxim solution.
• The pushed renormalized port-impedances can be examined at the port properties. Pushed source-settings can be viewed in the Edit Post Process Sources window.
• For pushing excitations to HFSS 3D Layout, there is a control for Target Solution. Its drop-down menu shows adaptive and discrete solutions that have the Save Fields option selected by default.

Error Handling

• If errors are encountered while calculating the impedances, a message are posted and excitations are not pushed.

• If invalid excitation values are pushed to HFSS, error messages are posted and the pushed values are not applied. Examples of invalid excitation values include:

  -inf impedance values

  <=0 system power