coupled_stripline.h

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/*
 * Copyright The KiCad Developers, see AUTHORS.txt for contributors.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this package; see the file COPYING.  If not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street - Fifth Floor,
 * Boston, MA 02110-1301, USA.
 */
 
#ifndef TRANSLINE_CALCULATIONS_COUPLED_STRIPLINE_H
#define TRANSLINE_CALCULATIONS_COUPLED_STRIPLINE_H
 
 
#include <transline_calculations/transline_calculation_base.h>
#include <transline_calculations/stripline.h>
 
#include <utility>
 
/*
 * This implements the calculations described in:
 *
 * [1] S. B. Cohn, "Characteristic Impedance of the Shielded-Strip Transmission Line," in Transactions of the IRE
 *    Professional Group on Microwave Theory and Techniques, vol. 2, no. 2, pp. 52-57, July 1954
 * [2] S. B. Cohn, "Shielded Coupled-Strip Transmission Line," in IRE Transactions on Microwave Theory and Techniques,
 *    vol. 3, no. 5, pp. 29-38, October 1955
 * [3] B. C. Wadell, "Transmission Line Design Handbook," Artech House, Norwood, MA, 1991.  Sec. 3.6.3
 *    "Off-Center Stripline" (Eqs. 3.6.3.21 - 3.6.3.23) gives the image-method plus three-term
 *    correction for a single strip offset between two ground planes; applied here per mode to the
 *    Reference [2] coupled-stripline solver.
 */
 
class COUPLED_STRIPLINE : public TRANSLINE_CALCULATION_BASE
{
    using TCP = TRANSLINE_PARAMETERS;
 
public:
    COUPLED_STRIPLINE() :
            TRANSLINE_CALCULATION_BASE( { TCP::SKIN_DEPTH, TCP::Z0_E, TCP::Z0_O, TCP::Z_DIFF, TCP::Z_COMM,
                                          TCP::COUPLING_K, TCP::PHYS_WIDTH, TCP::FREQUENCY, TCP::PHYS_LEN, TCP::H,
                                          TCP::PHYS_S, TCP::T, TCP::EPSILONR, TCP::MUR, TCP::MURC, TCP::SIGMA,
                                          TCP::TAND, TCP::ROUGH, TCP::ANG_L, TCP::STRIPLINE_A, TCP::ATTEN_COND_EVEN,
                                          TCP::ATTEN_COND_ODD, TCP::ATTEN_DILECTRIC_EVEN, TCP::ATTEN_DILECTRIC_ODD,
                                          TCP::DIELECTRIC_MODEL_SEL, TCP::EPSILONR_SPEC_FREQ } )
    {
    }

    void Analyse() override;

    bool Synthesize( SYNTHESIZE_OPTS aOpts ) override;

    static bool IsCenteredOffset( double a, double h );
 
private:
    void SetAnalysisResults() override;

    void SetSynthesisResults() override;

    enum class ResultSink
    {
        ANALYSIS,
        SYNTHESIS
    };

    void publishResults( ResultSink aSink, TRANSLINE_STATUS aImpedanceFailure, TRANSLINE_STATUS aGeometryFailure );

    double calcZ0SymmetricStripline();

    void calcFringeCapacitances( double h, double t, double er );

    void calcSingleStripImpedances();

    void calcZeroThicknessCoupledImpedances( double h, double w, double s, double er );

    static bool isOffsetWithinFiniteThicknessLimits( double a, double h, double t );

    void calcOffsetZeroThicknessCoupledImpedances( double h, double a, double w, double s, double t, double er );

    static double applyOffsetCorrection( double aZImage, double aOffset, double aPlateSpacing, double aWidth,
                                         double aThickness, double aEr );

    std::pair<double, double> calcOffsetVirtualBranch( double aVirtualH, double w, double s, double t, double er );

    void calcZ0EvenMode();

    void calcZ0OddMode( double t, double s );

    void calcLosses();

    void calcDielectrics();
 
    double C_f_0{ 0.0 };   
    double C_f_t_h{ 0.0 }; 
 
    double Z0_w_h_0{ 0.0 };       
    double Z0_w_h_t_h{ 0.0 };     
    double Z0_e_w_h_0_s_h{ 0.0 }; 
    double Z0_o_w_h_0_s_h{ 0.0 }; 
 
    double e_eff_e{ 0.0 };           
    double e_eff_o{ 0.0 };           
    double ang_l{ 0.0 };             
    double unit_prop_delay_e{ 0.0 }; 
    double unit_prop_delay_o{ 0.0 }; 

    STRIPLINE m_striplineCalc;
};
 
 
#endif //TRANSLINE_CALCULATIONS_COUPLED_STRIPLINE_H