11 December 2018
First, you can push both excitations simultaneously from a Circuit Model but keep in mind you can only view the fields one frequency at a time in HFSS. It might be simpler to create two separate Linear Network Analysis solution setups and analyse and push them separately.
To model your series capacitors properly, be sure to modify the pinouts of you HFSS N-Port block in Designer to have separate reference ports. Then wire the capacitor between these two connections for each respective port. The ports that drive your excitations will then have a GND symbol attached to their reference ports.
To assign a 1W excitation in Designer from a voltage you can back calculate the voltage amplitude since the port source impedance is fixed at 50 ohms. P = V^2/R; 1 = V^2/50; V = sqrt(50) = 7.071 V. - Keep in mind this is incident power and the actually power entering into the system will be scaled by the reflection coefficient of the port.
HFSS is a linear field solver - the power level can always be scaled linearly as a post-processing operation in HFSS by editing the value in the 'Fields -> Edit Source' menu... Keep in mind here that if you setup the circuit simulation to push multiple frequencies at once you will lose the ability to scale the fields from within HFSS - they will show up as a dynamically linked function in the 'Edit Sources' dialog... If you push excitations at just one frequency point, you will be able to see the actual power values pushed into each port and have the ability to edit them if needed...
Peter Serano - Senior Application Engineer - High Frequency Products