Hello,
This is regarding the port excitation plane with reference offset for the ports.
In the attached figure (edge.png), I have a 50 ohm trace (5mm length) and a 30 ohm trace. Port P1 is on the left edge of 50 ohm trace. Momentum will excite current across the edge (marked blue) , right.
Now , I have added 2mm reference offset to P1(Edge_2mmshift.png). Here also current will be excited at the blue line, right.
Next, I am changing the reference offset on P1 by 5mm (Edge_5mmshift.png). With this P1 lands on the intersection of 50 ohms and 30 ohms line. Will the the current excited across the 50 ohm line (blue line) or the 30 ohm line (the black line)?
This is regarding the port excitation plane with reference offset for the ports.
In the attached figure (edge.png), I have a 50 ohm trace (5mm length) and a 30 ohm trace. Port P1 is on the left edge of 50 ohm trace. Momentum will excite current across the edge (marked blue) , right.
Now , I have added 2mm reference offset to P1(Edge_2mmshift.png). Here also current will be excited at the blue line, right.
Next, I am changing the reference offset on P1 by 5mm (Edge_5mmshift.png). With this P1 lands on the intersection of 50 ohms and 30 ohms line. Will the the current excited across the 50 ohm line (blue line) or the 30 ohm line (the black line)?
> Next, I am changing the reference offset on P1 by 5mm (Edge_5mmshift.png). With this P1 lands on the intersection of 50 ohms and 30 ohms line. Will the the current excited across the 50 ohm line (blue line) or the 30 ohm line (the black line)?
The excited current will be across the 50 Ohm line, and results will include the step in width.
Think of it this way:
1. the full layout is simulated
2. calibration standards are simulated to calculate the port and feedlines properties
3. reference shift is done by cascading negative line length (with the calculated feedline properties) and the full model