diff --git a/FDTD/cartoperator.cpp b/FDTD/cartoperator.cpp
index 0caafdb..b5fe0f0 100644
--- a/FDTD/cartoperator.cpp
+++ b/FDTD/cartoperator.cpp
@@ -3,53 +3,42 @@
 CartOperator::CartOperator()
 {
     Init();
+	Operator::Init();
 }
 
 CartOperator::~CartOperator()
 {
 	Reset();
+	Operator::Reset();
 }
 
 void CartOperator::Init()
 {
-    CSX = NULL;
     MainOp=NULL;
     DualOp=NULL;
-	E_Ex_index = NULL;
-	E_Ex_delay = NULL;
-    for (int n=0;n<3;++n)
-    {
-		discLines[n]=NULL;
-        EC_C[n]=NULL;
-        EC_G[n]=NULL;
-        EC_L[n]=NULL;
-        EC_R[n]=NULL;
-		vv[n]=NULL;
-		vi[n]=NULL;
-		iv[n]=NULL;
-		ii[n]=NULL;
-		E_Ex_amp[n]=NULL;
+
+	for (int n=0;n<3;++n)
+	{
+		EC_C[n]=NULL;
+		EC_G[n]=NULL;
+		EC_L[n]=NULL;
+		EC_R[n]=NULL;
 	}
+
+	Operator::Init();
 }
 
 void CartOperator::Reset()
 {
-	delete[] E_Ex_index;
-	delete[] E_Ex_delay;
+	delete MainOp;
+	delete DualOp;
 	for (int n=0;n<3;++n)
 	{
 		delete[] EC_C[n];
 		delete[] EC_G[n];
 		delete[] EC_L[n];
 		delete[] EC_R[n];
-		delete[] vv[n];
-		delete[] vi[n];
-		delete[] iv[n];
-		delete[] ii[n];
-		delete[] E_Ex_amp[n];
 	}
-	delete MainOp;
-	delete DualOp;
 	Init();
 }
 
diff --git a/FDTD/cartoperator.h b/FDTD/cartoperator.h
index 07a52ce..911a014 100644
--- a/FDTD/cartoperator.h
+++ b/FDTD/cartoperator.h
@@ -1,57 +1,31 @@
 #ifndef CARTOPERATOR_H
 #define CARTOPERATOR_H
 
-#include "ContinuousStructure.h"
-#include "tools/AdrOp.h"
-#include "tools/constants.h"
+#include "operator.h"
 
-#define FDTD_FLOAT float
-
-class CartOperator
+class CartOperator : public Operator
 {
 public:
     CartOperator();
     virtual ~CartOperator();
 
-    void SetGeometryCSX(ContinuousStructure* geo);
+	virtual void SetGeometryCSX(ContinuousStructure* geo);
 
-	int CalcECOperator();
+	virtual int CalcECOperator();
 
-	void ApplyElectricBC(bool* dirs); //applied by default to all boundaries
-	void ApplyMagneticBC(bool* dirs);
+	virtual void ApplyElectricBC(bool* dirs); //applied by default to all boundaries
+	virtual void ApplyMagneticBC(bool* dirs);
 
-	double GetTimestep() {return dT;};
-
-    void Reset();
+	virtual void Reset();
 
 protected:
-    void Init();
-    ContinuousStructure* CSX;
+	virtual void Init();
 
     AdrOp* MainOp;
     AdrOp* DualOp;
-    double* discLines[3];
-    unsigned int numLines[3];
-	double gridDelta;
 
-	double dT; //FDTD timestep!
-
-	//EC operator
-	FDTD_FLOAT* vv[3]; //calc new voltage from old voltage
-	FDTD_FLOAT* vi[3]; //calc new voltage from old current
-	FDTD_FLOAT* ii[3]; //calc new current from old current
-	FDTD_FLOAT* iv[3]; //calc new current from old voltage
-
-	//E-Field Excitation
-	//!	  Calc the electric field excitation.
-	bool CalcEFieldExcitation();
-	unsigned int E_Ex_Count;
-	unsigned int* E_Ex_index;
-	FDTD_FLOAT* E_Ex_amp[3]; //represented as edge-voltages!!
-	FDTD_FLOAT* E_Ex_delay;
-
-	//Calc timestep only internal use
-	double CalcTimestep();
+	virtual bool CalcEFieldExcitation();
+	virtual double CalcTimestep();
 
 	//EC elements, internal only!
     bool Calc_EC();
diff --git a/FDTD/engine.cpp b/FDTD/engine.cpp
new file mode 100644
index 0000000..0c290cd
--- /dev/null
+++ b/FDTD/engine.cpp
@@ -0,0 +1,9 @@
+#include "engine.h"
+
+Engine::Engine()
+{
+}
+
+Engine::~Engine()
+{
+}
diff --git a/FDTD/engine.h b/FDTD/engine.h
new file mode 100644
index 0000000..07bca4a
--- /dev/null
+++ b/FDTD/engine.h
@@ -0,0 +1,17 @@
+#ifndef ENGINE_H
+#define ENGINE_H
+
+class Engine
+{
+public:
+    Engine();
+	virtual ~Engine();
+
+	//!Iterate a number of timesteps
+	bool IterateTS(unsigned int numTS);
+
+protected:
+
+};
+
+#endif // ENGINE_H
diff --git a/FDTD/operator.cpp b/FDTD/operator.cpp
new file mode 100644
index 0000000..a138aad
--- /dev/null
+++ b/FDTD/operator.cpp
@@ -0,0 +1,51 @@
+#include "operator.h"
+
+Operator::Operator()
+{
+	Operator::Init();
+}
+
+Operator::~Operator()
+{
+	Operator::Reset();
+}
+
+void Operator::Init()
+{
+	CSX = NULL;
+
+	E_Ex_index = NULL;
+	E_Ex_delay = NULL;
+	for (int n=0;n<3;++n)
+	{
+		discLines[n]=NULL;
+		vv[n]=NULL;
+		vi[n]=NULL;
+		iv[n]=NULL;
+		ii[n]=NULL;
+		E_Ex_amp[n]=NULL;
+	}
+}
+
+void Operator::Reset()
+{
+	delete[] E_Ex_index;
+	delete[] E_Ex_delay;
+	for (int n=0;n<3;++n)
+	{
+		delete[] vv[n];
+		delete[] vi[n];
+		delete[] iv[n];
+		delete[] ii[n];
+		delete[] E_Ex_amp[n];
+	}
+	Operator::Init();
+}
+
+void Operator::SetGeometryCSX(ContinuousStructure* geo)
+{
+	if (geo==NULL) return;
+
+	Reset();
+	CSX = geo;
+}
diff --git a/FDTD/operator.h b/FDTD/operator.h
new file mode 100644
index 0000000..38f9f75
--- /dev/null
+++ b/FDTD/operator.h
@@ -0,0 +1,56 @@
+#ifndef OPERATOR_H
+#define OPERATOR_H
+
+#include "ContinuousStructure.h"
+#include "tools/AdrOp.h"
+#include "tools/constants.h"
+
+#define FDTD_FLOAT float
+
+//! Abstract base-class for the FDTD-operator
+class Operator
+{
+	friend class Engine;
+public:
+    Operator();
+	virtual ~Operator();
+
+	virtual void SetGeometryCSX(ContinuousStructure* geo);
+
+	virtual int CalcECOperator() {};
+
+	virtual void ApplyElectricBC(bool* dirs) {}; //applied by default to all boundaries
+	virtual void ApplyMagneticBC(bool* dirs) {};
+
+	double GetTimestep() {return dT;};
+
+	virtual void Reset();
+
+protected:
+	virtual void Init();
+	ContinuousStructure* CSX;
+	double gridDelta;
+
+	double* discLines[3];
+	unsigned int numLines[3];
+
+	//EC operator
+	FDTD_FLOAT* vv[3]; //calc new voltage from old voltage
+	FDTD_FLOAT* vi[3]; //calc new voltage from old current
+	FDTD_FLOAT* ii[3]; //calc new current from old current
+	FDTD_FLOAT* iv[3]; //calc new current from old voltage
+
+	//E-Field Excitation
+	//!	  Calc the electric field excitation.
+	virtual bool CalcEFieldExcitation() {};
+	unsigned int E_Ex_Count;
+	unsigned int* E_Ex_index;
+	FDTD_FLOAT* E_Ex_amp[3]; //represented as edge-voltages!!
+	FDTD_FLOAT* E_Ex_delay;
+
+	//Calc timestep only internal use
+	virtual double CalcTimestep() {};
+	double dT; //FDTD timestep!
+};
+
+#endif // OPERATOR_H
diff --git a/openEMS.pro b/openEMS.pro
index 1510f1e..bbd644a 100644
--- a/openEMS.pro
+++ b/openEMS.pro
@@ -17,8 +17,12 @@ LIBS += -L../CSXCAD \
 SOURCES += main.cpp \
     FDTD/cartoperator.cpp \
     tools/ErrorMsg.cpp \
-    tools/AdrOp.cpp
+    tools/AdrOp.cpp \
+    FDTD/engine.cpp \
+    FDTD/operator.cpp
 HEADERS += FDTD/cartoperator.h \
     tools/ErrorMsg.h \
     tools/AdrOp.h \
-    tools/constants.h
+    tools/constants.h \
+    FDTD/engine.h \
+    FDTD/operator.h