Qucs-core  0.0.19
msrstub.cpp
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00001 /*
00002  * msrstub.cpp - microstrip radial stub class implementation
00003  *
00004  * Copyright (C) 2009 Stefan Jahn <stefan@lkcc.org>
00005  *
00006  * This is free software; you can redistribute it and/or modify
00007  * it under the terms of the GNU General Public License as published by
00008  * the Free Software Foundation; either version 2, or (at your option)
00009  * any later version.
00010  *
00011  * This software is distributed in the hope that it will be useful,
00012  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00013  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00014  * GNU General Public License for more details.
00015  *
00016  * You should have received a copy of the GNU General Public License
00017  * along with this package; see the file COPYING.  If not, write to
00018  * the Free Software Foundation, Inc., 51 Franklin Street - Fifth Floor,
00019  * Boston, MA 02110-1301, USA.
00020  *
00021  * $Id$
00022  *
00023  */
00024 
00025 #if HAVE_CONFIG_H
00026 # include <config.h>
00027 #endif
00028 
00029 #include "component.h"
00030 #include "substrate.h"
00031 #include "msrstub.h"
00032 
00033 using namespace qucs;
00034 
00035 msrstub::msrstub () : circuit (1) {
00036   type = CIR_MSRSTUB;
00037 }
00038 
00039 // Returns the microstrip radial stub reactance.
00040 nr_double_t msrstub::calcReactance (nr_double_t r1, nr_double_t r2,
00041                                     nr_double_t alpha, nr_double_t er,
00042                                     nr_double_t h, nr_double_t frequency) {
00043 
00044   nr_double_t l0 = C0 / frequency;
00045   nr_double_t W = (r1 + (r2 - r1) / 2) * deg2rad (alpha);
00046   nr_double_t ereff = (er + 1.0) / 2 + (er - 1.0) /
00047     (2.0 * qucs::sqrt (1 + 10.0 * h / W));
00048   nr_double_t k = 2.0 * pi * qucs::sqrt (ereff) / l0;
00049   nr_double_t a = k * r1;
00050   nr_double_t b = k * r2;
00051   nr_double_t Z_0 = Z0 / qucs::sqrt (ereff) * qucs::sqrt (sqr (j0 (a)) + sqr (y0 (a))) /
00052     qucs::sqrt (sqr (j1 (a)) + sqr (y1 (a)));
00053   nr_double_t theta_1 = qucs::atan (y0 (a) / j0 (a));
00054   //  nr_double_t theta_2 = atan (y0 (b) / j0 (b));
00055   nr_double_t phi_1 = qucs::atan (-j1 (a) / y1 (a));
00056   nr_double_t phi_2 = qucs::atan (-j1 (b) / y1 (b));
00057 
00058   nr_double_t X1 = h * Z_0 / (2.0 * pi * r1) * 360.0 / alpha *
00059     qucs::cos (theta_1 - phi_2) / qucs::sin (phi_1 - phi_2);
00060 
00061   return X1;
00062 }
00063 
00064 void msrstub::calcSP (nr_double_t frequency) {
00065   setS (NODE_1, NODE_1, ztor (calcZ (frequency)));
00066 }
00067 
00068 nr_complex_t msrstub::calcZ (nr_double_t frequency) {
00069 
00070   /* get properties of this component */
00071   nr_double_t r1 = getPropertyDouble ("ri");
00072   nr_double_t r2 = getPropertyDouble ("ro");
00073   nr_double_t al = getPropertyDouble ("alpha");
00074 
00075   /* get properties of the substrate */
00076   substrate * subst = getSubstrate ();
00077   nr_double_t er    = subst->getPropertyDouble ("er");
00078   nr_double_t h     = subst->getPropertyDouble ("h");
00079 
00080   return nr_complex_t (0, calcReactance (r1, r2, al, er, h, frequency));
00081 }
00082 
00083 void msrstub::initDC (void) {
00084   allocMatrixMNA ();
00085   setY (NODE_1, NODE_1, 0);
00086 }
00087 
00088 void msrstub::calcAC (nr_double_t frequency) {
00089   setY (NODE_1, NODE_1, 1.0 / calcZ (frequency));
00090 }
00091 
00092 // properties
00093 PROP_REQ [] = {
00094   { "ri", PROP_REAL, { 1e-3, PROP_NO_STR }, PROP_POS_RANGE },
00095   { "ro", PROP_REAL, { 10e-3, PROP_NO_STR }, PROP_POS_RANGE },
00096   { "alpha", PROP_REAL, { 90, PROP_NO_STR }, PROP_RNGII (0, 180) },
00097   { "Subst", PROP_STR, { PROP_NO_VAL, "Subst1" }, PROP_NO_RANGE },
00098   PROP_NO_PROP };
00099 PROP_OPT [] = {
00100   PROP_NO_PROP };
00101 struct define_t msrstub::cirdef =
00102   { "MRSTUB", 1, PROP_COMPONENT, PROP_NO_SUBSTRATE, PROP_LINEAR, PROP_DEF };