199 lines
5.3 KiB
C++
199 lines
5.3 KiB
C++
/*
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* stripline.cpp - stripline class definition
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*
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* Copyright (C) 2011 Michael Margraf <michael.margraf@alumni.tu-berlin.de>
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* Modifications 2011 for Kicad: Jean-Pierre Charras
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or (at
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* your option) any later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this package; see the file COPYING. If not, write to
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* the Free Software Foundation, Inc., 51 Franklin Street - Fifth Floor,
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* Boston, MA 02110-1301, USA.
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*
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*/
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#include <stdlib.h>
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#include <stdio.h>
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#include <string.h>
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#include <math.h>
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#include <units.h>
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#include <transline.h>
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#include <stripline.h>
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STRIPLINE::STRIPLINE() : TRANSLINE()
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{
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m_name = "StripLine";
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}
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// -------------------------------------------------------------------
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void STRIPLINE::getProperties()
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{
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f = getProperty( FREQUENCY_PRM );
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w = getProperty( PHYS_WIDTH_PRM );
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len = getProperty( PHYS_LEN_PRM );
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h = getProperty( H_PRM);
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a = getProperty( STRIPLINE_A_PRM );
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t = getProperty( T_PRM );
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er = getProperty( EPSILONR_PRM );
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murC = getProperty( MURC_PRM );
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tand = getProperty( TAND_PRM );
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sigma = 1.0 / getProperty( RHO_PRM );
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Z0 = getProperty( Z0_PRM );
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ang_l = getProperty( ANG_L_PRM );
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}
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// -------------------------------------------------------------------
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// calculate characteristic impedance and conductor loss
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double STRIPLINE::lineImpedance( double height, double& ac )
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{
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double ZL;
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double hmt = height - t;
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ac = sqrt( f / sigma / 17.2 );
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if( w / hmt >= 0.35 )
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{
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ZL = w +
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( 2.0 * height *
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log( (2.0 * height - t) / hmt ) - t * log( height * height / hmt / hmt - 1.0 ) ) / M_PI;
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ZL = ZF0 * hmt / sqrt( er ) / 4.0 / ZL;
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ac *= 2.02e-6 * er * ZL / hmt;
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ac *= 1.0 + 2.0 * w / hmt + (height + t) / hmt / M_PI* log( 2.0 * height / t - 1.0 );
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}
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else
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{
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double tdw = t / w;
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if( t / w > 1.0 )
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tdw = w / t;
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double de = 1.0 + tdw / M_PI * ( 1.0 + log( 4.0 * M_PI / tdw ) ) + 0.236 * pow( tdw, 1.65 );
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if( t / w > 1.0 )
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de *= t / 2.0;
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else
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de *= w / 2.0;
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ZL = ZF0 / 2.0 / M_PI / sqrt( er ) * log( 4.0 * height / M_PI / de );
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ac *= 0.01141 / ZL / de;
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ac *= de / height + 0.5 + tdw / 2.0 / M_PI + 0.5 / M_PI* log( 4.0 * M_PI / tdw )
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+ 0.1947 * pow( tdw, 0.65 ) - 0.0767 * pow( tdw, 1.65 );
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}
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return ZL;
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}
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// -------------------------------------------------------------------
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void STRIPLINE::calc()
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{
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skindepth = skin_depth();
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er_eff = er; // no dispersion
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double ac1, ac2;
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Z0 = 2.0 /
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( 1.0 / lineImpedance( 2.0 * a + t, ac1 ) + 1.0 / lineImpedance( 2.0 * (h - a) - t, ac2 ) );
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atten_cond = len * 0.5 * (ac1 + ac2);
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atten_dielectric = 20.0 / log( 10.0 ) * len * (M_PI / C0) * f * sqrt( er ) * tand;
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ang_l = 2.0* M_PI* len* sqrt( er ) * f / C0; // in radians
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}
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// -------------------------------------------------------------------
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void STRIPLINE::show_results()
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{
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setProperty( Z0_PRM, Z0 );
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setProperty( ANG_L_PRM, ang_l );
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setResult( 0, er_eff, "" );
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setResult( 1, atten_cond, "dB" );
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setResult( 2, atten_dielectric, "dB" );
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setResult( 3, skindepth / UNIT_MICRON, "<EFBFBD>m" );
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}
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// -------------------------------------------------------------------
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void STRIPLINE::analyze()
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{
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getProperties();
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calc();
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show_results();
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}
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#define MAX_ERROR 0.000001
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// -------------------------------------------------------------------
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void STRIPLINE::synthesize()
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{
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double Z0_dest, Z0_current, Z0_result, increment, slope, error;
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int iteration;
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getProperties();
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/* required value of Z0 */
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Z0_dest = Z0;
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/* Newton's method */
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iteration = 0;
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/* compute parameters */
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calc();
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Z0_current = Z0;
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error = fabs( Z0_dest - Z0_current );
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while( error > MAX_ERROR )
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{
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iteration++;
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increment = w / 100.0;
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w += increment;
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/* compute parameters */
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calc();
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Z0_result = Z0;
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/* f(w(n)) = Z0 - Z0(w(n)) */
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/* f'(w(n)) = -f'(Z0(w(n))) */
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/* f'(Z0(w(n))) = (Z0(w(n)) - Z0(w(n+delw))/delw */
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/* w(n+1) = w(n) - f(w(n))/f'(w(n)) */
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slope = (Z0_result - Z0_current) / increment;
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slope = (Z0_dest - Z0_current) / slope - increment;
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w += slope;
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if( w <= 0.0 )
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w = increment;
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/* find new error */
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/* compute parameters */
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calc();
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Z0_current = Z0;
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error = fabs( Z0_dest - Z0_current );
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if( iteration > 100 )
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break;
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}
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setProperty( PHYS_WIDTH_PRM, w );
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/* calculate physical length */
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ang_l = getProperty( ANG_L_PRM );
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len = C0 / f / sqrt( er_eff ) * ang_l / 2.0 / M_PI; /* in m */
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setProperty( PHYS_LEN_PRM, len );
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/* compute parameters */
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calc();
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/* print results in the subwindow */
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show_results();
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}
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