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CPW-Simulation with Sonnet/MWO: Current-Conservation

Dear Community

I got demo-Versions of Microwave Office and Sonnet (Lite).

When I draw a CPW with ground-planes touching the side-wall and two
ports on the Signal-Wire on both ends (Edge-Ports) I found out that in
such a situation both Microwave Office and Sonnet give currents such
that the sum of currents on grounds and singal-wires do not vanish but
there's about 15 % too much on the signal wire.

MWO: If I use internal ports, then I get current conservation

Sonnet: Using push-pull ports, I get current-conservation too.

Can anyone please explain me why there's no current-conservation in the
first case?

Since for my MWO design I cannot rely on internal ports, can anyone
please tell how to get current conservation using edge-ports?

Thanks
Pascal
 
J

Joel Kolstad

Jan 1, 1970
0
When I draw a CPW with ground-planes touching the side-wall and two
ports on the Signal-Wire on both ends (Edge-Ports) I found out that in
such a situation both Microwave Office and Sonnet give currents such
that the sum of currents on grounds and singal-wires do not vanish but
there's about 15 % too much on the signal wire.

Both MWO and Sonnet Lite use grided field solvers that have a grounded "box"
surrounded the geometry. My guess would be that part of the current goes back
to the box itself via displacement currents (coupling). You could test this
idea by making the box smaller and seeing if you "lose" more current.

I'm not sure why the internal ports would promote current conservation...

In general both AWR and Sonnet have very good technical support, so you
shouldn't have any problem getting them to help you with it.

---Joel
 
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