Qucs filter: Fix for the warning related to the new features

Some warnings remained after merging Qucs#415. In this commit, two unused
variables are removed at qw_coupled_ring_filter.cpp. Moreover, the
substrate parameters for the capacitively coupled shunt resonators are
removed since there's no microstrip synthesis available

qucs/qucs-filter/ccoupled_shunt_resonators.cpp

@@ -42,7 +42,7 @@ CCoupled_Shunt_Resonator_Filter::CCoupled_Shunt_Resonator_Filter()
 
 // -----------------------------------------------------------------------
 // This function generates the schematic
-QString* CCoupled_Shunt_Resonator_Filter::createSchematic(tFilter *Filter, tSubstrate *Substrate, bool isMicrostrip)
+QString* CCoupled_Shunt_Resonator_Filter::createSchematic(tFilter *Filter)
 {
 //Design equations
 double f0 = Filter->Frequency+0.5*(Filter->Frequency2-Filter->Frequency);//Central frequency

qucs/qucs-filter/ccoupled_shunt_resonators.h

@@ -31,7 +31,7 @@ class CCoupled_Shunt_Resonator_Filter : public TL_Filter {
 public:
   CCoupled_Shunt_Resonator_Filter();
 
-  static QString* createSchematic(tFilter*, tSubstrate*, bool);
+  static QString* createSchematic(tFilter*);
 };
 
 #endif

qucs/qucs-filter/qucsfilter.cpp

@@ -418,7 +418,7 @@ QString * QucsFilter::calculateFilter(struct tFilter * Filter)
         s = QW_Coupled_Ring_Filter::createSchematic(Filter, &Substrate, isMicrostrip);
         return s;
       case 7: // Capacitively coupled shunt resonators
-        s = CCoupled_Shunt_Resonator_Filter::createSchematic(Filter, &Substrate, isMicrostrip);
+        s = CCoupled_Shunt_Resonator_Filter::createSchematic(Filter);
         return s;
       case 8:  // equation defined filter
         s = Equation_Filter::createSchematic(Filter);

qucs/qucs-filter/qw_coupled_ring_filter.cpp

@@ -52,9 +52,7 @@ QString* QW_Coupled_Ring_Filter::createSchematic(tFilter *Filter, tSubstrate *Su
   double y = 0.01; // Bandpass ripple (dB)
   double Ye = 1/Ze;
   double x = -pow(10,(-y/20));
-  double rf = ftz/f0;//Ratio between the first transmission zero and the central frequency
   double TZ = (sin(pi*ftz/(2*f0))*sin(pi*ftz/(2*f0)))/(1 + cos(pi*ftz/(2*f0))*cos(pi*ftz/(2*f0)));
-  double theta_tz = pi*ftz/(2*f0);
   double SQ = sqrt((1-x*x)*(TZ*TZ-1)*(TZ*TZ-1)*Z0*Z0);
   double R = -Ye*Z0*(Z0*(x*x-2)+2*SQ);
   double Q = 2*TZ*TZ*Ye*Z0*(Z0*(x*x-2)+SQ);