Updates to wire dipole example.

docs/source/examples_antennas.rst

@@ -22,6 +22,21 @@ This example demonstrates a model of a half-wavelength wire dipole antenna in fr
 
 The antenna is fed using the ``#tranmission_line`` command. The one-dimensional transmission line model virtually attaches to the dipole at the gap between the arms. The antenna has an input impedance :math:`Z_0` of 73 Ohms specified in the ``#tranmission_line`` command. The transmission line uses a Gaussian waveform with a centre frequency of 1GHz.
 
+Results
+-------
+
+.. _antenna_wire_dipole_fs_tl_params:
+
+.. figure:: images/antenna_wire_dipole_fs_tl_params.png
+
+    Time and frequency domain plots of the incident and reflected (scattered) voltages in the transmission line.
+
+.. _antenna_wire_dipole_fs_ant_params:
+
+    .. figure:: images/antenna_wire_dipole_fs_ant_params.png
+
+    s11 parameter and input impedance (resistance and reactance) of the antenna.
+
 
 Bowtie antenna model
 ====================

tools/plot_Bscan.py

@@ -58,6 +58,7 @@ if 'E' in args.field:
     cb.set_label('Field strength [V/m]')
 elif 'H' in args.field:
     cb.set_label('Field strength [A/m]')
+
 plt.show()
 #fig.savefig(os.path.splitext(os.path.abspath(file))[0] + '.pdf', dpi=None, format='pdf', bbox_inches='tight', pad_inches=0.1)
 f.close()

tools/plot_antenna_params.py

@@ -16,7 +16,7 @@
 # You should have received a copy of the GNU General Public License
 # along with gprMax.  If not, see <http://www.gnu.org/licenses/>.
 
-import argparse
+import os, argparse
 import h5py
 import numpy as np
 np.seterr(divide='ignore', invalid='ignore')
@@ -25,10 +25,10 @@ import matplotlib.gridspec as gridspec
 
 from gprMax.exceptions import CmdInputError
 
-"""Plots the s11 scattering parameter (input port voltage reflection coefficient) from an output file containing a transmission line source."""
+"""Plots antenna parameters (s11 parameter and input impedance) from an output file containing a transmission line source."""
 
 # Parse command line arguments
-parser = argparse.ArgumentParser(description='Plots the s11 scattering parameter (input port voltage reflection coefficient) from an output file containing a transmission line source.', usage='cd gprMax; python -m tools.plot_s11 outputfile')
+parser = argparse.ArgumentParser(description='Plots antenna parameters (s11 parameter and input impedance) from an output file containing a transmission line source.', usage='cd gprMax; python -m tools.plot_antenna_params outputfile')
 parser.add_argument('outputfile', help='name of output file including path')
 parser.add_argument('-tln', default=1, type=int, help='transmission line number')
 args = parser.parse_args()
@@ -44,6 +44,7 @@ time = time / 1e-9
 path = '/tls/tl' + str(args.tln) + '/'
 Vinc = f[path + 'Vinc'][:]
 Vscat = f[path + 'Vscat'][:]
+Iscat = f[path + 'Iscat'][:]
 Vtotal = f[path +'Vtotal'][:]
 
 # Calculate magnitude of frequency spectra
@@ -51,6 +52,8 @@ Vincp = np.abs(np.fft.fft(Vinc))**2
 freqs = np.fft.fftfreq(Vincp.size, d=dt)
 Vscatp = np.abs(np.fft.fft(Vscat))**2
 s11 = Vscatp / Vincp
+zin = np.zeros(iterations, dtype=np.complex)
+zin = np.abs(np.fft.fft(Vscat)) / np.abs(np.fft.fft(Iscat))
 
 # Convert to decibels
 Vincp = 10 * np.log10(Vincp)
@@ -62,55 +65,92 @@ pltrange = np.where((np.amax(Vincp) - Vincp) > 60)[0][0] + 1
 pltrange = np.s_[0:pltrange]
 
 # Plot incident voltage
-plt.subplots(num='Transmission line voltages & s11 parameter', figsize=(20, 10), facecolor='w', edgecolor='w')
+fig1, ax = plt.subplots(num='Transmission line parameters', figsize=(20, 10), facecolor='w', edgecolor='w')
-gs = gridspec.GridSpec(3, 2)
+gs1 = gridspec.GridSpec(2, 2, hspace=0.3)
-ax1 = plt.subplot(gs[0, 0])
+ax1 = plt.subplot(gs1[0, 0])
 ax1.plot(time, Vinc, 'r', lw=2, label='Vinc')
+ax1.set_title('Incident voltage')
 ax1.set_xlabel('Time [ns]')
-ax1.set_ylabel('Incident voltage [V]')
+ax1.set_ylabel('Voltage [V]')
 ax1.set_xlim([0, np.amax(time)])
 ax1.grid()
 
 # Plot frequency spectra of incident voltage
-ax2 = plt.subplot(gs[0, 1])
+ax2 = plt.subplot(gs1[0, 1])
 markerline, stemlines, baseline = ax2.stem(freqs[pltrange]/1e9, Vincp[pltrange], '-.')
 plt.setp(baseline, 'linewidth', 0)
 plt.setp(stemlines, 'color', 'r')
 plt.setp(markerline, 'markerfacecolor', 'r', 'markeredgecolor', 'r')
 ax2.plot(freqs[pltrange]/1e9, Vincp[pltrange], 'r', lw=2)
+ax2.set_title('Incident voltage')
 ax2.set_xlabel('Frequency [GHz]')
-ax2.set_ylabel('Incident voltage spectra [dB]')
+ax2.set_ylabel('Power [dB]')
 ax2.grid()
 
 # Plot scattered (field) voltage
-ax3 = plt.subplot(gs[1, 0])
+ax3 = plt.subplot(gs1[1, 0])
 ax3.plot(time, Vscat, 'r', lw=2, label='Vscat')
+ax3.set_title('Reflected voltage')
 ax3.set_xlabel('Time [ns]')
-ax3.set_ylabel('Scattered (field) voltage [V]')
+ax3.set_ylabel('Voltage [V]')
 ax3.set_xlim([0, np.amax(time)])
 ax3.grid()
 
 # Plot frequency spectra of scattered voltage
-ax4 = plt.subplot(gs[1, 1])
+ax4 = plt.subplot(gs1[1, 1])
 markerline, stemlines, baseline = ax4.stem(freqs[pltrange]/1e9, Vscatp[pltrange], '-.')
 plt.setp(baseline, 'linewidth', 0)
 plt.setp(stemlines, 'color', 'r')
 plt.setp(markerline, 'markerfacecolor', 'r', 'markeredgecolor', 'r')
 ax4.plot(freqs[pltrange]/1e9, Vscatp[pltrange], 'r', lw=2)
+ax4.set_title('Reflected voltage')
 ax4.set_xlabel('Frequency [GHz]')
-ax4.set_ylabel('Scattered (field) voltage spectra [dB]')
+ax4.set_ylabel('Power [dB]')
 ax4.grid()
 
 # Plot frequency spectra of s11
-ax5 = plt.subplot(gs[2, 1])
+fig2, ax = plt.subplots(num='Antenna parameters', figsize=(20, 10), facecolor='w', edgecolor='w')
+gs2 = gridspec.GridSpec(3, 1, hspace=0.5)
+ax5 = plt.subplot(gs2[0, 0])
 markerline, stemlines, baseline = ax5.stem(freqs[pltrange]/1e9, s11[pltrange], '-.')
 plt.setp(baseline, 'linewidth', 0)
 plt.setp(stemlines, 'color', 'r')
 plt.setp(markerline, 'markerfacecolor', 'r', 'markeredgecolor', 'r')
 ax5.plot(freqs[pltrange]/1e9, s11[pltrange], 'r', lw=2)
+ax5.set_title('s11 parameter')
 ax5.set_xlabel('Frequency [GHz]')
-ax5.set_ylabel('s11 [dB]')
+ax5.set_ylabel('Power [dB]')
 ax5.grid()
 
+# Plot input resistance (real part of impedance)
+ax6 = plt.subplot(gs2[1, 0])
+markerline, stemlines, baseline = ax6.stem(freqs[pltrange]/1e9, zin[pltrange].real, '-.')
+plt.setp(baseline, 'linewidth', 0)
+plt.setp(stemlines, 'color', 'r')
+plt.setp(markerline, 'markerfacecolor', 'r', 'markeredgecolor', 'r')
+ax6.plot(freqs[pltrange]/1e9, zin[pltrange].real, 'r', lw=2)
+ax6.set_title('Input impedance')
+ax6.set_xlabel('Frequency [GHz]')
+ax6.set_ylabel('Resistance [Ohms]')
+ax6.set_ylim(bottom=0)
+ax6.grid()
+
+# Plot input reactance (imaginery part of impedance)
+ax7 = plt.subplot(gs2[2, 0])
+markerline, stemlines, baseline = ax7.stem(freqs[pltrange]/1e9, zin[pltrange].imag, '-.')
+plt.setp(baseline, 'linewidth', 0)
+plt.setp(stemlines, 'color', 'r')
+plt.setp(markerline, 'markerfacecolor', 'r', 'markeredgecolor', 'r')
+ax7.plot(freqs[pltrange]/1e9, zin[pltrange].imag, 'r', lw=2)
+ax7.set_title('Input impedance')
+ax7.set_xlabel('Frequency [GHz]')
+ax7.set_ylabel('Reactance [Ohms]')
+ax7.set_ylim(bottom=0)
+ax7.grid()
+
 plt.show()
+fig1.savefig(os.path.splitext(os.path.abspath(file))[0] + '_tl_params.png', dpi=150, format='png', bbox_inches='tight', pad_inches=0.1)
+fig2.savefig(os.path.splitext(os.path.abspath(file))[0] + '_ant_params.png', dpi=150, format='png', bbox_inches='tight', pad_inches=0.1)
+#fig1.savefig(os.path.splitext(os.path.abspath(file))[0] + '_tl_params.pdf', dpi=None, format='pdf', bbox_inches='tight', pad_inches=0.1)
+#fig2.savefig(os.path.splitext(os.path.abspath(file))[0] + '_ant_params.pdf', dpi=None, format='pdf', bbox_inches='tight', pad_inches=0.1)
 f.close()