gprMax/tools/plot_antenna_params.py

# Copyright (C) 2015: The University of Edinburgh
#            Authors: Craig Warren and Antonis Giannopoulos
#
# This file is part of gprMax.
#
# gprMax 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 3 of the License, or
# (at your option) any later version.
#
# gprMax 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 gprMax.  If not, see <http://www.gnu.org/licenses/>.

import os, argparse
import h5py
import numpy as np
np.seterr(divide='ignore', invalid='ignore')
import matplotlib.pyplot as plt
import matplotlib.gridspec as gridspec

from gprMax.exceptions import CmdInputError

"""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 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()

# Open output file and read some attributes
file = args.outputfile
f = h5py.File(file, 'r')
dt = f.attrs['dt']
iterations = f.attrs['Iterations']
time = np.arange(0, dt * iterations, dt)
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
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)
Vscatp = 10 * np.log10(Vscatp)
s11 = 10 * np.log10(s11)

# Set plotting range to -60dB from maximum power
pltrange = np.where((np.amax(Vincp) - Vincp) > 60)[0][0] + 1
pltrange = np.s_[0:pltrange]

# Plot incident voltage
fig1, ax = plt.subplots(num='Transmission line parameters', figsize=(20, 10), facecolor='w', edgecolor='w')
gs1 = gridspec.GridSpec(2, 2, hspace=0.3)
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('Voltage [V]')
ax1.set_xlim([0, np.amax(time)])
ax1.grid()

# Plot frequency spectra of incident voltage
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('Power [dB]')
ax2.grid()

# Plot scattered (field) voltage
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('Voltage [V]')
ax3.set_xlim([0, np.amax(time)])
ax3.grid()

# Plot frequency spectra of scattered voltage
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('Power [dB]')
ax4.grid()

# Plot frequency spectra of s11
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('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()