How to connect lumped component and .s2p on a finite ground design?

Hello members,

I am designing a structurecontaining patch antenna and some passive components where I have to place .s2p data of capacitors and lumped resistor from ADS "lumped components library".

I have got completely different result in infinite ground MoM (very good result) and finite ground MoM case (worst result). I might have done mistakes in case of finite ground MoM case. Near to patch, I have kept ground plane size 3 times of width and length of patch accordingly. I have also changed the port calibration from TML to AUTO in finite ground case, but the response is same.

Please see thefollowing figures taken from Co-simulation (Yellow is bottom finite ground and orange is the top metal). In all cases, ground pin is 0.1mm away from the + pin. The design frequency is 10 GHz.

^^ Lumped resistor

^^ s2p componets

^^ Term component

What are the two unconncted pins in your EM lookalike? Are these the ground pins?

If yes, connect the ground of your S2P to one of these local grounds pins (not global schematic ground).

Yes Sir,

Those two unconnected pins are ground pins.

For .s2p reference connection, do I need to connect it to both the ground pins?

For, lumped component, will I keep it like the attached picture above, keeping the ground pin unconnected?

For a pure series elements like your ideal resistor, the ground location does not matter. But for a real component (S2P) that has series + shunt impedance, the ground path matters. For finite ground models with ground pin, use that.

Connect it to one of the ground pins. You can choose one side, it doesn't make much difference.

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