Length matched traces

Trial-and-Error and the trace length information from the net highlighter are your simplest bet. You can also hack proper-looking matched-length traces by using the Microwave tools. Open the Microwave Toolbar and select "Create line of specified length for microwave applications". Drag a rectangle and input the length of the accordion trace you wish to create. Give the module a reference name such as MLT1 and set its value to the length (this will help you later when calculating total trace length).

What will be created is a module (footprint) with a copper-layer graphic of the specified length and pads at the ends. Line width equals the current trace width and internal distance is twice the current clearance. The created module has a module/footprint of MuSelf (itself). The copper-layer graphic does not interact with traces and pads so you will need to be careful with other elements around it as DRC will not work.

You must then go into your schematic and add a MLT symbol in-line with the trace you are length-matching. Set its reference and value to the values you used earlier. Update the netlist and open and save the updated netlist in CvPCB. Edit the Module Comparison file (.cmp) in a text editor (not in CvPCB) by changing all the MLT traces to module type MuSelf. Change all the appropriate IdModule = MuSelf

When you highlight a net you will need to manually add the MLT lengths to come up with the total trace length.

There already exists a bug for how matched length traces would work:
https://bugs.launchpad.net/bugs/594089

The idea is for any trace segment to be extended to its maximum length with a right-click menu item. I have made several attempts to implement such functionality but it is very difficult to automate adding traces outside of the drawing paradigm. If someone more familiar with PCBnew knows how to add arbitrary traces (start_point, end_point, net_name) please contact me. I could really use some help.

It is also possible to alter the Microwave tool for arbitrary length and width by asking for bounding box details. Code for an earlier revision is included below.

Here is a MLT schematic symbol library (MLT.lib):

EESchema-LIBRARY Version 12/2/2009 11:48:39 PM
#
#
# MLT
#
DEF ~MLT MLT 0 40 Y N 1 F N
F0 "MLT" 0 52 30 H V C CNN
F1 "MLT" 0 52 30 H I C CNN
$FPLIST
 MuSelf
$ENDFPLIST
DRAW
A -36 -13 12 -1799 -1 0 1 0 N -48 -13 -23 -13
P 3 0 1 0 -48 0 -50 0 -50 0 N
P 3 0 1 0 -24 -13 -24 12 -24 12 N
P 4 0 1 0 48 11 48 0 50 0 50 0 N
P 3 0 1 0 -48 0 -48 -12 -48 -12 N
A 36 11 12 1 1799 0 1 0 N 48 11 23 11
A 12 -15 12 -1799 -1 0 1 0 N 0 -15 25 -15
A -12 11 12 1 1799 0 1 0 N 0 11 -25 11
P 3 0 1 0 0 -14 0 11 0 11 N
P 3 0 1 0 24 -14 24 11 24 11 N
X 2 2 100 0 50 L 25 25 1 1 B
X 1 1 -100 0 50 R 25 25 1 1 B
ENDDRAW
ENDDEF
#
#EndLibrary

Changes to allow arbitrary Microwave tool bounding box, circa BZR2100, starting at Line 256 of muonde.cpp:

   /* Enter the desired bounding length of the inductor. */
   if( !g_UnitMetric )
   {
       fcoeff = 10000.0;
       msg.Printf( wxT( "%1.4f" ), Mself.m_Size.y / fcoeff );
       abort = Get_Message( _( "Bounding Length (inch):" ), _("Length" ), msg, this );
   }
   else
   {
       fcoeff = 10000.0 / 25.4;
       msg.Printf( wxT( "%2.3f" ), Mself.m_Size.y / fcoeff );
       abort = Get_Message( _( "Bounding Length (mm):" ), _( "Length"), msg, this );
   }
   if( abort )
       return NULL;

   if( !msg.ToDouble( &fval ) )
   {
       DisplayError( this, _( "Incorrect Bounding Length Value; aborting" ) );
       return NULL;
   }
   Mself.m_Size.y = wxRound( fval * fcoeff );

   /* Adjust end point location to account for longer bounding length */
   if (Mself.m_Size.y > abs(Mself.m_End.x - Mself.m_Start.x))
   {
       if( Mself.orient == 0 )
       {
           Mself.m_End.x = Mself.m_Start.x + Mself.m_Size.y;
       }
       else
       {
           Mself.m_End.y = Mself.m_Start.y + Mself.m_Size.y;
       }
   }

   /* Enter the desired bounding width of the inductor. */
   if( !g_UnitMetric )
   {
       fcoeff = 10000.0;
       msg.Printf( wxT( "%1.4f" ), Mself.m_Size.x / fcoeff );
       abort = Get_Message( _( "Bounding Width (inch):" ), _( "Width"), msg, this );
   }
   else
   {
       fcoeff = 10000.0 / 25.4;
       msg.Printf( wxT( "%2.3f" ), Mself.m_Size.x / fcoeff );
       abort = Get_Message( _( "Bounding Width (mm):" ), _( "Width"), msg, this );
   }
   if( abort )
       return NULL;

   if( !msg.ToDouble( &fval ) )
   {
       DisplayError( this, _( "Incorrect Bounding Width Value; aborting" ) );
       return NULL;
   }
   Mself.m_Size.x = wxRound( fval * fcoeff );