diff --git a/pcb_calculator/calculator_panels/panel_transline_base.cpp b/pcb_calculator/calculator_panels/panel_transline_base.cpp
index cd821fdeb3..9ba1d0955a 100644
--- a/pcb_calculator/calculator_panels/panel_transline_base.cpp
+++ b/pcb_calculator/calculator_panels/panel_transline_base.cpp
@@ -1,5 +1,5 @@
 ///////////////////////////////////////////////////////////////////////////
-// C++ code generated with wxFormBuilder (version 3.10.0-4761b0c5)
+// C++ code generated with wxFormBuilder (version 3.10.0)
 // http://www.wxformbuilder.org/
 //
 // PLEASE DO *NOT* EDIT THIS FILE!
@@ -22,7 +22,7 @@ PANEL_TRANSLINE_BASE::PANEL_TRANSLINE_BASE( wxWindow* parent, wxWindowID id, con
 	wxString m_TranslineSelectionChoices[] = { _("Microstrip Line"), _("Coplanar wave guide"), _("Coplanar wave guide w/ ground plane"), _("Rectangular Waveguide"), _("Coaxial Line"), _("Coupled Microstrip Line"), _("Stripline"), _("Twisted Pair") };
 	int m_TranslineSelectionNChoices = sizeof( m_TranslineSelectionChoices ) / sizeof( wxString );
 	m_TranslineSelection = new wxRadioBox( this, wxID_ANY, _("Transmission Line Type"), wxDefaultPosition, wxDefaultSize, m_TranslineSelectionNChoices, m_TranslineSelectionChoices, 1, wxRA_SPECIFY_COLS );
-	m_TranslineSelection->SetSelection( 2 );
+	m_TranslineSelection->SetSelection( 0 );
 	bLeftSizer->Add( m_TranslineSelection, 0, wxTOP|wxRIGHT|wxLEFT|wxEXPAND, 5 );
 
 
@@ -216,27 +216,6 @@ PANEL_TRANSLINE_BASE::PANEL_TRANSLINE_BASE( wxWindow* parent, wxWindowID id, con
 	m_bmCMicrostripZoddZeven = new wxStaticBitmap( this, wxID_ANY, wxNullBitmap, wxDefaultPosition, wxDefaultSize, 0 );
 	bSizerHelpBitmaps->Add( m_bmCMicrostripZoddZeven, 0, wxALL|wxALIGN_CENTER_HORIZONTAL, 10 );
 
-	m_fgSizerZcomment = new wxFlexGridSizer( 0, 2, 0, 15 );
-	m_fgSizerZcomment->AddGrowableCol( 0 );
-	m_fgSizerZcomment->AddGrowableCol( 1 );
-	m_fgSizerZcomment->SetFlexibleDirection( wxBOTH );
-	m_fgSizerZcomment->SetNonFlexibleGrowMode( wxFLEX_GROWMODE_SPECIFIED );
-
-	m_staticTextZdiff = new wxStaticText( this, wxID_ANY, _("Zdiff =\n2*Z0( (1 - 0.48exp( -0.96*S/H ) )"), wxDefaultPosition, wxDefaultSize, 0 );
-	m_staticTextZdiff->Wrap( -1 );
-	m_staticTextZdiff->SetFont( wxFont( wxNORMAL_FONT->GetPointSize(), wxFONTFAMILY_DEFAULT, wxFONTSTYLE_ITALIC, wxFONTWEIGHT_NORMAL, false, wxEmptyString ) );
-
-	m_fgSizerZcomment->Add( m_staticTextZdiff, 0, wxALL|wxALIGN_CENTER_HORIZONTAL, 5 );
-
-	m_staticTextZcommon = new wxStaticText( this, wxID_ANY, _("Zcommon = Zeven / 2"), wxDefaultPosition, wxDefaultSize, wxALIGN_CENTER_HORIZONTAL );
-	m_staticTextZcommon->Wrap( -1 );
-	m_staticTextZcommon->SetFont( wxFont( wxNORMAL_FONT->GetPointSize(), wxFONTFAMILY_DEFAULT, wxFONTSTYLE_ITALIC, wxFONTWEIGHT_NORMAL, false, wxEmptyString ) );
-
-	m_fgSizerZcomment->Add( m_staticTextZcommon, 0, wxALIGN_CENTER_HORIZONTAL|wxALL, 5 );
-
-
-	bSizerHelpBitmaps->Add( m_fgSizerZcomment, 0, wxEXPAND, 5 );
-
 
 	bMiddleSizer->Add( bSizerHelpBitmaps, 1, wxALIGN_CENTER_HORIZONTAL, 5 );
 
diff --git a/pcb_calculator/calculator_panels/panel_transline_base.fbp b/pcb_calculator/calculator_panels/panel_transline_base.fbp
index 47b275ce40..bc7b6cfc66 100644
--- a/pcb_calculator/calculator_panels/panel_transline_base.fbp
+++ b/pcb_calculator/calculator_panels/panel_transline_base.fbp
@@ -116,7 +116,7 @@
                                 <property name="pin_button">1</property>
                                 <property name="pos"></property>
                                 <property name="resize">Resizable</property>
-                                <property name="selection">2</property>
+                                <property name="selection">0</property>
                                 <property name="show">1</property>
                                 <property name="size"></property>
                                 <property name="style">wxRA_SPECIFY_COLS</property>
@@ -2038,11 +2038,11 @@
                                 </object>
                             </object>
                         </object>
-                        <object class="sizeritem" expanded="0">
+                        <object class="sizeritem" expanded="1">
                             <property name="border">5</property>
                             <property name="flag">wxEXPAND|wxTOP</property>
                             <property name="proportion">0</property>
-                            <object class="wxStaticBoxSizer" expanded="0">
+                            <object class="wxStaticBoxSizer" expanded="1">
                                 <property name="id">wxID_ANY</property>
                                 <property name="label">Component Parameters</property>
                                 <property name="minimum_size"></property>
@@ -2326,146 +2326,6 @@
                                         <property name="window_style"></property>
                                     </object>
                                 </object>
-                                <object class="sizeritem" expanded="1">
-                                    <property name="border">5</property>
-                                    <property name="flag">wxEXPAND</property>
-                                    <property name="proportion">0</property>
-                                    <object class="wxFlexGridSizer" expanded="1">
-                                        <property name="cols">2</property>
-                                        <property name="flexible_direction">wxBOTH</property>
-                                        <property name="growablecols">0,1</property>
-                                        <property name="growablerows"></property>
-                                        <property name="hgap">15</property>
-                                        <property name="minimum_size"></property>
-                                        <property name="name">m_fgSizerZcomment</property>
-                                        <property name="non_flexible_grow_mode">wxFLEX_GROWMODE_SPECIFIED</property>
-                                        <property name="permission">protected</property>
-                                        <property name="rows">0</property>
-                                        <property name="vgap">0</property>
-                                        <object class="sizeritem" expanded="1">
-                                            <property name="border">5</property>
-                                            <property name="flag">wxALL|wxALIGN_CENTER_HORIZONTAL</property>
-                                            <property name="proportion">0</property>
-                                            <object class="wxStaticText" expanded="1">
-                                                <property name="BottomDockable">1</property>
-                                                <property name="LeftDockable">1</property>
-                                                <property name="RightDockable">1</property>
-                                                <property name="TopDockable">1</property>
-                                                <property name="aui_layer"></property>
-                                                <property name="aui_name"></property>
-                                                <property name="aui_position"></property>
-                                                <property name="aui_row"></property>
-                                                <property name="best_size"></property>
-                                                <property name="bg"></property>
-                                                <property name="caption"></property>
-                                                <property name="caption_visible">1</property>
-                                                <property name="center_pane">0</property>
-                                                <property name="close_button">1</property>
-                                                <property name="context_help"></property>
-                                                <property name="context_menu">1</property>
-                                                <property name="default_pane">0</property>
-                                                <property name="dock">Dock</property>
-                                                <property name="dock_fixed">0</property>
-                                                <property name="docking">Left</property>
-                                                <property name="enabled">1</property>
-                                                <property name="fg"></property>
-                                                <property name="floatable">1</property>
-                                                <property name="font">,93,92,-1,70,0</property>
-                                                <property name="gripper">0</property>
-                                                <property name="hidden">0</property>
-                                                <property name="id">wxID_ANY</property>
-                                                <property name="label">Zdiff =&#x0A;2*Z0( (1 - 0.48exp( -0.96*S/H ) )</property>
-                                                <property name="markup">0</property>
-                                                <property name="max_size"></property>
-                                                <property name="maximize_button">0</property>
-                                                <property name="maximum_size"></property>
-                                                <property name="min_size"></property>
-                                                <property name="minimize_button">0</property>
-                                                <property name="minimum_size"></property>
-                                                <property name="moveable">1</property>
-                                                <property name="name">m_staticTextZdiff</property>
-                                                <property name="pane_border">1</property>
-                                                <property name="pane_position"></property>
-                                                <property name="pane_size"></property>
-                                                <property name="permission">protected</property>
-                                                <property name="pin_button">1</property>
-                                                <property name="pos"></property>
-                                                <property name="resize">Resizable</property>
-                                                <property name="show">1</property>
-                                                <property name="size"></property>
-                                                <property name="style"></property>
-                                                <property name="subclass">; ; forward_declare</property>
-                                                <property name="toolbar_pane">0</property>
-                                                <property name="tooltip"></property>
-                                                <property name="window_extra_style"></property>
-                                                <property name="window_name"></property>
-                                                <property name="window_style"></property>
-                                                <property name="wrap">-1</property>
-                                            </object>
-                                        </object>
-                                        <object class="sizeritem" expanded="0">
-                                            <property name="border">5</property>
-                                            <property name="flag">wxALIGN_CENTER_HORIZONTAL|wxALL</property>
-                                            <property name="proportion">0</property>
-                                            <object class="wxStaticText" expanded="0">
-                                                <property name="BottomDockable">1</property>
-                                                <property name="LeftDockable">1</property>
-                                                <property name="RightDockable">1</property>
-                                                <property name="TopDockable">1</property>
-                                                <property name="aui_layer"></property>
-                                                <property name="aui_name"></property>
-                                                <property name="aui_position"></property>
-                                                <property name="aui_row"></property>
-                                                <property name="best_size"></property>
-                                                <property name="bg"></property>
-                                                <property name="caption"></property>
-                                                <property name="caption_visible">1</property>
-                                                <property name="center_pane">0</property>
-                                                <property name="close_button">1</property>
-                                                <property name="context_help"></property>
-                                                <property name="context_menu">1</property>
-                                                <property name="default_pane">0</property>
-                                                <property name="dock">Dock</property>
-                                                <property name="dock_fixed">0</property>
-                                                <property name="docking">Left</property>
-                                                <property name="enabled">1</property>
-                                                <property name="fg"></property>
-                                                <property name="floatable">1</property>
-                                                <property name="font">,93,92,-1,70,0</property>
-                                                <property name="gripper">0</property>
-                                                <property name="hidden">0</property>
-                                                <property name="id">wxID_ANY</property>
-                                                <property name="label">Zcommon = Zeven / 2</property>
-                                                <property name="markup">0</property>
-                                                <property name="max_size"></property>
-                                                <property name="maximize_button">0</property>
-                                                <property name="maximum_size"></property>
-                                                <property name="min_size"></property>
-                                                <property name="minimize_button">0</property>
-                                                <property name="minimum_size"></property>
-                                                <property name="moveable">1</property>
-                                                <property name="name">m_staticTextZcommon</property>
-                                                <property name="pane_border">1</property>
-                                                <property name="pane_position"></property>
-                                                <property name="pane_size"></property>
-                                                <property name="permission">protected</property>
-                                                <property name="pin_button">1</property>
-                                                <property name="pos"></property>
-                                                <property name="resize">Resizable</property>
-                                                <property name="show">1</property>
-                                                <property name="size"></property>
-                                                <property name="style">wxALIGN_CENTER_HORIZONTAL</property>
-                                                <property name="subclass"></property>
-                                                <property name="toolbar_pane">0</property>
-                                                <property name="tooltip"></property>
-                                                <property name="window_extra_style"></property>
-                                                <property name="window_name"></property>
-                                                <property name="window_style"></property>
-                                                <property name="wrap">-1</property>
-                                            </object>
-                                        </object>
-                                    </object>
-                                </object>
                             </object>
                         </object>
                     </object>
diff --git a/pcb_calculator/calculator_panels/panel_transline_base.h b/pcb_calculator/calculator_panels/panel_transline_base.h
index cbae05b6df..1ddc7f2331 100644
--- a/pcb_calculator/calculator_panels/panel_transline_base.h
+++ b/pcb_calculator/calculator_panels/panel_transline_base.h
@@ -1,5 +1,5 @@
 ///////////////////////////////////////////////////////////////////////////
-// C++ code generated with wxFormBuilder (version 3.10.0-4761b0c5)
+// C++ code generated with wxFormBuilder (version 3.10.0)
 // http://www.wxformbuilder.org/
 //
 // PLEASE DO *NOT* EDIT THIS FILE!
@@ -80,9 +80,6 @@ class PANEL_TRANSLINE_BASE : public CALCULATOR_PANEL
 		wxTextCtrl* m_Value_Frequency_Ctrl;
 		UNIT_SELECTOR_FREQUENCY* m_choiceUnit_Frequency;
 		wxStaticBitmap* m_bmCMicrostripZoddZeven;
-		wxFlexGridSizer* m_fgSizerZcomment;
-		wxStaticText* m_staticTextZdiff;
-		wxStaticText* m_staticTextZcommon;
 		wxStaticText* m_phys_prm1_label;
 		wxTextCtrl* m_Phys_prm1_Value;
 		UNIT_SELECTOR_LEN* m_choiceUnit_Param1;
diff --git a/pcb_calculator/transline/c_microstrip.cpp b/pcb_calculator/transline/c_microstrip.cpp
index 1189cdfeff..fcde0e9018 100644
--- a/pcb_calculator/transline/c_microstrip.cpp
+++ b/pcb_calculator/transline/c_microstrip.cpp
@@ -583,12 +583,14 @@ void C_MICROSTRIP::line_angle()
 }
 
 
-/*
-* diff_impedance() - calculate differential impedance
-*/
+/**
+ * Note that differential impedance is exactly twice the odd mode impedance.
+ * Odd mode is not the same as single-ended impedance, so avoid approximations found
+ * on websites that use static single ended impedance as the starting point
+ */
 void C_MICROSTRIP::diff_impedance()
 {
-    Zdiff = 2*Z0_o_0*(1 - 0.48*exp(-0.96*(m_parameters[PHYS_S_PRM] /m_parameters[H_PRM])));
+    Zdiff = 2 * Z0_o_0;
 }
 
 
diff --git a/pcb_calculator/transline_dlg_funct.cpp b/pcb_calculator/transline_dlg_funct.cpp
index 7190fd6922..c03fb71856 100644
--- a/pcb_calculator/transline_dlg_funct.cpp
+++ b/pcb_calculator/transline_dlg_funct.cpp
@@ -187,7 +187,6 @@ void PANEL_TRANSLINE::TranslineTypeSelection( enum TRANSLINE_TYPE_ID aType )
     // This helper bitmap is shown for coupled microstrip only:
     m_bmCMicrostripZoddZeven->Show( aType == C_MICROSTRIP_TYPE );
     m_bmCMicrostripZoddZeven->SetBitmap( KiBitmap( BITMAPS::microstrip_zodd_zeven ) );
-    m_fgSizerZcomment->Show( aType == C_MICROSTRIP_TYPE );
 
     TRANSLINE_IDENT* tr_ident = m_transline_list[m_currTransLineType];
     m_currTransLine = tr_ident->m_TLine;