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How to analyze a slotline in EMPOWER

Question asked by ROB_LEFEBVRE on Mar 26, 2003
EMPOWER can easily handle slot-type circuits.  It has many unique capabilities make it ideal for slotline.  There are two GENESYS 2003 files attached to this message (Although slot-mode works in all versions of EMPOWER, these files require GENESYS 2003):

Slotline.wsp: Shows a simple slotline analysis in GENESYS.  You can easily see the possible frequency of operation, approximately 6 to 15 GHz.

Slotline stub.wsp: Shows a circuit using slotline.  The stub was simply cut out of the rectangle.  This circuit is shown in the figure below.

There are a few of things you setup to analyze a slotline circuit in GENESYS:

1) Be sure that the metal layer is set to "Slot-type" in the EMPOWER Layers tab in LAYOUT.  This will dramatically speed up simulation.

2) The EM Ports must be carefully setup: the width, height, and current direction must be specified.  Set the width to the slot width, the height to one EMPOWER grid cell, and set the current direction to be parallel to the edge of the box (Along Y for ports on the left or right, and Along X for ports on top or bottom of the layout).

3) The polgyon used for the slotline stub will not trigger the EMPOWER line detection properly.  You must place rectangles (not polygons) along the edge on top of any polygons, as was done in the Slotline Stub example.  Note that this step was not necessary in the simple Slotline example because only rectangles were used.  Note that any rectangles with cut-outs automatically turn into polygons.

4) In the EMPOWER properties, General tab, you must set "Generalized" for port impedance, since these lines are not 50 ohm lines.

5) In the EMPOWER properties, General tab, you must set the Max critical freq LOW (below the frequency of transmission) so that the line mode analysis uses a long enough segment of line to setup the wave propagation.  In this example, we set the value to 3 GHz, and transmission is from 6 to 15 GHz.

6) In the EMPOWER properties, Advanced tab, slide the "Thinning out" slider all the way to the left to disable thinning out.

[file]slotline stub.wsp[/file]