diff --git a/matlab/AddMSLPort.m b/matlab/AddMSLPort.m
index 10ebdf5..3b6314d 100644
--- a/matlab/AddMSLPort.m
+++ b/matlab/AddMSLPort.m
@@ -122,6 +122,13 @@ else
     direction = -1;
 end
 
+% direction of propagation
+if stop(idx_height)-start(idx_height) > 0
+    upsidedown = +1;
+else
+    upsidedown = -1;
+end
+
 % create the metal/material for the MSL
 MSL_start = start;
 MSL_stop = stop;
@@ -177,7 +184,7 @@ i2_stop(idx_prop)    = i2_start(idx_prop);
 % create the probes
 name = ['port_ut' num2str(portnr) 'A'];
 % weight = sign(stop(idx_height)-start(idx_height))
-weight = -1;
+weight = upsidedown;
 CSX = AddProbe( CSX, name, 0, weight );
 CSX = AddBox( CSX, name, prio, v1_start, v1_stop );
 name = ['port_ut' num2str(portnr) 'B'];
@@ -196,13 +203,18 @@ CSX = AddProbe( CSX, name, 1, weight );
 CSX = AddBox( CSX, name, prio, i2_start, i2_stop );
 
 % create port structure
+port.LengthScale = 1;
+if ((CSX.ATTRIBUTE.CoordSystem==1) && (idx_prop==2))
+    port.LengthScale = MSL_stop(idx_height);
+end
 port.nr = portnr;
 port.drawingunit = CSX.RectilinearGrid.ATTRIBUTE.DeltaUnit;
-port.v_delta = diff(meshlines);
-port.i_delta = diff( meshlines(1:end-1) + diff(meshlines)/2 );
+port.v_delta = diff(meshlines)*port.LengthScale;
+port.i_delta = diff( meshlines(1:end-1) + diff(meshlines)/2 )*port.LengthScale;
 port.direction = direction;
 port.excite = 0;
-port.measplanepos = abs(v2_start(idx_prop) - start(idx_prop));
+port.measplanepos = abs(v2_start(idx_prop) - start(idx_prop))*port.LengthScale;
+% port
 
 % create excitation
 % excitation of this port is enabled
diff --git a/matlab/calcPort.m b/matlab/calcPort.m
index f6a5b9b..1e1dbb8 100644
--- a/matlab/calcPort.m
+++ b/matlab/calcPort.m
@@ -1,5 +1,5 @@
 function [port] = calcPort( port, SimDir, f, varargin)
-% [port] = calcPort( port, SimDir, f, [ref_ZL], [ref_shift])
+% [port] = calcPort( port, SimDir, f, varargin)
 %
 % Calculate voltages and currents, the propagation constant beta
 % and the characteristic impedance ZL of the given port.
@@ -11,12 +11,13 @@ function [port] = calcPort( port, SimDir, f, varargin)
 %   f:          frequency vector for DFT
 % 
 % variable input:
-%   'RefImpedance': use a given reference impedance to calculate inc and
-%                   ref voltages and currents
-%                   default is given port or calculated line impedance
-%   'RefPlaneShift': use a given reference plane shift from port beginning
-%                   for a desired phase correction
-%                   default is the measurement plane 
+%   'RefImpedance':  - use a given reference impedance to calculate inc and
+%                      ref voltages and currents
+%                    - default is given port or calculated line impedance
+%   'RefPlaneShift': - use a given reference plane shift from port beginning
+%                      for a desired phase correction
+%                    - default is the measurement plane
+%                    - the plane shift has to be given in drawing units!
 %
 % output: 
 %   port.f                  the given frequency fector
@@ -90,9 +91,10 @@ ZL = sqrt(Et .* dEt ./ (Ht .* dHt));
 
 % reference plane shift (lossless)
 if ~isnan(ref_shift)
-    % renormalize the shift to the measurement plane
-    ref_shift = ref_shift - port.measplanepos * port.drawingunit;
-%     ref_shift = ref_shift * port.drawingunit;
+    ref_shift = ref_shift * port.LengthScale;
+    % shift to the beginning of MSL
+    ref_shift = ref_shift - port.measplanepos;
+    ref_shift = ref_shift * port.drawingunit;
     
     % store the shifted frequency domain waveforms
     phase = real(beta)*ref_shift;