Driving two rectangular wave ports differentially in HFSS?

Gents,

I have two identical cross-section rectangular waveguides in a driven model. How do I drive these two waveguides differentially (i.e. TE10 for each, but 180 degree out of phase) in HFSS? Do I need to use a driven terminal model instead?

-J

Welcome jwh,

The setup you have will work. In the left hand menu, right click on "Field Overlays" -> "Edit Sources". In the window that pops up, you can set the phase of each excitation.

PlanarMetamaterials -- thank you very much.

When post-processing the data, is there any way to present the S parameters differentially? That is, if I have ports 1 & 2 driving the structure with ports 3 & 4 on the other end and I'm trying to tune the insertion loss, can I plot S_{4-3}{2-1} to get the differential for scattering parameter instead of looking at S(3,2) and S(3,1), S(4,2) and S(4,1), etc?

Also, when driving the structure differentially, I get the following information note from HFSS for each frequency point:
"Discreet Solution, process hf3d: Port 3 supports an additional propagating and/or slowly decaying mode whose attenuation is xxxx and propagation constant is xxx"

Of note, I only see that message in regard to Port 3 -- not ports 1,2, or 4. I'm executing an interpolating sweep. In addition, each wave port is defined with one mode, the integration lines are all in the same direction/orientation. Should I set each wave port to support multiple higher-order modes to suppress this message?

Regards,
J

jwh said:

When post-processing the data, is there any way to present the S parameters differentially? That is, if I have ports 1 & 2 driving the structure with ports 3 & 4 on the other end and I'm trying to tune the insertion loss, can I plot S_{4-3}{2-1} to get the differential for scattering parameter instead of looking at S(3,2) and S(3,1), S(4,2) and S(4,1), etc?

Click to expand...

Unfortunately I don't believe so. You'll have to do this manually.

jwh said:

Also, when driving the structure differentially, I get the following information note from HFSS for each frequency point:
"Discreet Solution, process hf3d: Port 3 supports an additional propagating and/or slowly decaying mode whose attenuation is xxxx and propagation constant is xxx"
Of note, I only see that message in regard to Port 3 -- not ports 1,2, or 4. I'm executing an interpolating sweep. In addition, each wave port is defined with one mode, the integration lines are all in the same direction/orientation. Should I set each wave port to support multiple higher-order modes to suppress this message?

Click to expand...

I've actually not seen that one before. It sounds like your setup is correct. Yes, you could simulate an additional mode and see what happens, I'd also try running a discrete frequency sweep instead.

Good Luck