401 lines
9.8 KiB
C++
401 lines
9.8 KiB
C++
/*
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* rectwaveguide.cpp - rectangular waveguide class implementation
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*
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* Copyright (C) 2001 Gopal Narayanan <gopal@astro.umass.edu>
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* Copyright (C) 2005, 2006 Stefan Jahn <stefan@lkcc.org>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at 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,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU 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 <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 "rectwaveguide.h"
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RECTWAVEGUIDE::RECTWAVEGUIDE() : TRANSLINE()
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{
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m_name = "RectWaveGuide";
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}
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/*
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* returns square of k
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*/
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double RECTWAVEGUIDE::kval_square()
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{
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double kval;
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kval = 2.0* M_PI* f* sqrt( mur* er ) / C0;
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return kval * kval;
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}
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/*
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* given mode numbers m and n
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* returns square of cutoff kc value
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*/
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double RECTWAVEGUIDE::kc_square( int m, int n )
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{
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return pow( (m * M_PI / a), 2.0 ) + pow( (n * M_PI / b), 2.0 );
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}
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/*
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* given mode numbers m and n
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* returns cutoff fc value
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*/
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double RECTWAVEGUIDE::fc( int m, int n )
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{
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return sqrt( kc_square( m, n ) / mur / er ) * C0 / 2.0 / M_PI;
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}
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/*
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* alphac - returns attenuation due to conductor losses for all propagating
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* modes in the waveguide
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*/
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double RECTWAVEGUIDE::alphac()
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{
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double Rs, f_c;
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double ac;
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short m, n, mmax, nmax;
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Rs = sqrt( M_PI * f * murC * MU0 / sigma );
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ac = 0.0;
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mmax = (int) floor( f / fc( 1, 0 ) );
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nmax = mmax;
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/* below from Ramo, Whinnery & Van Duzer */
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/* TE(m,n) modes */
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for( n = 0; n<= nmax; n++ )
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{
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for( m = 1; m <= mmax; m++ )
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{
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f_c = fc( m, n );
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if( f > f_c )
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{
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switch( n )
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{
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case 0:
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ac += ( Rs / ( b * ZF0 * sqrt( 1.0 - pow( (f_c / f), 2.0 ) ) ) ) *
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( 1.0 + ( (2 * b / a) * pow( (f_c / f), 2.0 ) ) );
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break;
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default:
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ac += ( (2. * Rs) / ( b * ZF0 * sqrt( 1.0 - pow( (f_c / f), 2.0 ) ) ) ) *
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( ( ( 1. + (b / a) ) * pow( (f_c / f), 2.0 ) ) +
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( ( 1. -
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pow( (f_c / f),
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2.0 ) ) *
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( ( (b / a) * ( ( (b / a) * pow( m, 2. ) ) + pow( n, 2. ) ) ) /
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( pow( (b * m / a),
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2.0 ) + pow( n, 2.0 ) ) ) ) );
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break;
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}
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}
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}
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}
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/* TM(m,n) modes */
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for( n = 1; n<= nmax; n++ )
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{
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for( m = 1; m<= mmax; m++ )
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{
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f_c = fc( m, n );
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if( f > f_c )
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{
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ac += ( (2. * Rs) / ( b * ZF0 * sqrt( 1.0 - pow( (f_c / f), 2.0 ) ) ) ) *
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( ( ( pow( m, 2.0 ) * pow( (b / a), 3.0 ) ) + pow( n, 2. ) ) /
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( ( pow( (m * b / a), 2. ) ) + pow( n, 2.0 ) ) );
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}
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}
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}
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ac = ac * 20.0 * log10( exp( 1. ) ); /* convert from Np/m to db/m */
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return ac;
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}
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/*
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* alphac_cutoff - returns attenuation for a cutoff wg
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*/
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double RECTWAVEGUIDE::alphac_cutoff()
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{
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double acc;
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acc = sqrt( kc_square( 1, 0 ) - kval_square() );
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acc = 20 * log10( exp( 1.0 ) ) * acc;
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return acc;
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}
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/*
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* returns attenuation due to dielectric losses
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*/
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double RECTWAVEGUIDE::alphad()
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{
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double k_square, beta;
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double ad;
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k_square = kval_square();
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beta = sqrt( k_square - kc_square( 1, 0 ) );
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ad = (k_square * tand) / (2.0 * beta);
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ad = ad * 20.0 * log10( exp( 1. ) ); /* convert from Np/m to db/m */
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return ad;
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}
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/*
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* get_rectwaveguide_sub
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* get and assign rectwaveguide substrate parameters
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* into rectwaveguide structure
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*/
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void RECTWAVEGUIDE::get_rectwaveguide_sub()
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{
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er = getProperty( EPSILONR_PRM );
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mur = getProperty( MUR_PRM );
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murC = getProperty( MURC_PRM );
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sigma = 1.0 / getProperty( RHO_PRM );
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tand = getProperty( TAND_PRM );
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tanm = getProperty( TANM_PRM );
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}
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/*
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* get_rectwaveguide_comp
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* get and assign rectwaveguide component parameters
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* into rectwaveguide structure
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*/
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void RECTWAVEGUIDE::get_rectwaveguide_comp()
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{
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f = getProperty( FREQUENCY_PRM );
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}
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/*
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* get_rectwaveguide_elec
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* get and assign rectwaveguide electrical parameters
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* into rectwaveguide structure
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*/
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void RECTWAVEGUIDE::get_rectwaveguide_elec()
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{
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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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* get_rectwaveguide_phys
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* get and assign rectwaveguide physical parameters
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* into rectwaveguide structure
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*/
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void RECTWAVEGUIDE::get_rectwaveguide_phys()
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{
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a = getProperty( PHYS_WIDTH_PRM );
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b = getProperty( PHYS_S_PRM );
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l = getProperty( PHYS_LEN_PRM );
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}
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/*
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* analyze - analysis function
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*/
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void RECTWAVEGUIDE::analyze()
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{
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double lambda_g;
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double k_square;
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/* Get and assign substrate parameters */
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get_rectwaveguide_sub();
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/* Get and assign component parameters */
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get_rectwaveguide_comp();
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/* Get and assign physical parameters */
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get_rectwaveguide_phys();
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k_square = kval_square();
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if( kc_square( 1, 0 ) <= k_square )
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{
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/* propagating modes */
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// Z0 definition using fictive voltages and currents
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Z0 = 2.0* ZF0* sqrt( mur / er ) * (b / a) / sqrt( 1.0 - pow( (fc( 1, 0 ) / f), 2.0 ) );
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/* calculate electrical angle */
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lambda_g = 2.0 * M_PI / sqrt( k_square - kc_square( 1, 0 ) );
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ang_l = 2.0 * M_PI * l / lambda_g; /* in radians */
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atten_cond = alphac() * l;
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atten_dielectric = alphad() * l;
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er_eff = ( 1.0 - pow( fc( 1, 0 ) / f, 2.0 ) );
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}
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else
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{
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/* evanascent modes */
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Z0 = 0;
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ang_l = 0;
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er_eff = 0;
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atten_dielectric = 0.0;
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atten_cond = alphac_cutoff() * l;
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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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show_results();
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}
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/*
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* synthesize - synthesis function
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*/
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void RECTWAVEGUIDE::synthesize()
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{
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double lambda_g, k_square, beta;
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/* Get and assign substrate parameters */
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get_rectwaveguide_sub();
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/* Get and assign component parameters */
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get_rectwaveguide_comp();
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/* Get and assign electrical parameters */
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get_rectwaveguide_elec();
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/* Get and assign physical parameters */
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get_rectwaveguide_phys();
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if( isSelected( PHYS_S_PRM ) )
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{
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/* solve for b */
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b = Z0 * a * sqrt( 1.0 - pow( fc( 1, 0 ) / f, 2.0 ) ) / ( 2.0 * ZF0 * sqrt( mur / er ) );
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setProperty( PHYS_S_PRM, b );
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}
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else if( isSelected( PHYS_WIDTH_PRM ) )
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{
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/* solve for a */
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a = sqrt( pow( 2.0 * ZF0 * b / Z0, 2.0 ) + pow( C0 / (2.0 * f), 2.0 ) );
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setProperty( PHYS_WIDTH_PRM, a );
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}
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k_square = kval_square();
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beta = sqrt( k_square - kc_square( 1, 0 ) );
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lambda_g = 2.0 * M_PI / beta;
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l = (ang_l * lambda_g) / (2.0 * M_PI); /* in m */
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setProperty( PHYS_LEN_PRM, l );
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if( kc_square( 1, 0 ) <= k_square )
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{
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/*propagating modes */
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beta = sqrt( k_square - kc_square( 1, 0 ) );
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lambda_g = 2.0 * M_PI / beta;
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atten_cond = alphac() * l;
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atten_dielectric = alphad() * l;
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er_eff = ( 1.0 - pow( (fc( 1, 0 ) / f), 2.0 ) );
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}
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else
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{
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/*evanascent modes */
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Z0 = 0;
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ang_l = 0;
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er_eff = 0;
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atten_dielectric = 0.0;
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atten_cond = alphac_cutoff() * l;
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}
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show_results();
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}
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#define MAXSTRLEN 128
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void RECTWAVEGUIDE::show_results()
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{
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int m, n, max = 6;
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char text[MAXSTRLEN], txt[32];
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// Z0EH = Ey / Hx (definition with field quantities)
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Z0EH = ZF0 * sqrt( kval_square() / ( kval_square() - kc_square( 1, 0 ) ) );
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setResult( 0, Z0EH, "Ohm" );
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setResult( 1, er_eff, "" );
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setResult( 2, atten_cond, "dB" );
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setResult( 3, atten_dielectric, "dB" );
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// show possible TE modes (H modes)
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if( f < fc( 1, 0 ) )
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strcpy( text, "none" );
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else
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{
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strcpy( text, "" );
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for( m = 0; m<= max; m++ )
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{
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for( n = 0; n<= max; n++ )
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{
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if( (m == 0) && (n == 0) )
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continue;
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if( f >= ( fc( m, n ) ) )
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{
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sprintf( txt, "H(%u,%u) ", m, n );
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if( (strlen( text ) + strlen( txt ) + 5) < MAXSTRLEN )
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strcat( text, txt );
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else
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{
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strcat( text, "..." );
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m = n = max + 1; // print no more modes
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}
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}
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}
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}
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}
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setResult( 4, text );
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// show possible TM modes (E modes)
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if( f < fc( 1, 1 ) )
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strcpy( text, "none" );
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else
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{
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strcpy( text, "" );
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for( m = 1; m<= max; m++ )
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{
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for( n = 1; n<= max; n++ )
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{
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if( f >= fc( m, n ) )
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{
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sprintf( txt, "E(%u,%u) ", m, n );
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if( (strlen( text ) + strlen( txt ) + 5) < MAXSTRLEN )
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strcat( text, txt );
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else
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{
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strcat( text, "..." );
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m = n = max + 1; // print no more modes
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}
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}
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}
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}
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}
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setResult( 5, text );
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}
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