What is ANSYS HFSS System Gain?

System gain is a far field quantity that help designers see the impact of circuit design on HFSS farfields calculation.

System gain is 4π times the ratio of an antenna's radiation intensity in a given direction to the user specified power. The system gain is a useful quantity when performing an HFSS-Circuit co simulation, e.g. using circuit to create a matching network or feed network for an HFSS antenna design. This gain quantity will show the impact of matching on the realized gain. Otherwise, the "Gain" and "Realized Gain" quantities will not show the circuit impact on the gain calculation as these quantities are calculated based on the calculated total power accepted or incident  upon the antenna port(s).

System gain appears in the Quantity list if Edit Sources was used to specify system power for gain calculations. For system gain calculations,  you need to select Specify System Power in the edit sources window.  The system power typically comes from an external circuit (e.g., a Circuit project) when the user push the excitations from the circuit simulation, and is used in computing System Realized Gain in antenna parameters and System Gain in far field reports.