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"""Test the dispersion-compensated algorithm package."""
import numpy as np
import scipy.constants as sc
# SciKit-RF: https://scikit-rf.readthedocs.io/
from skrf.frequency import Frequency
from skrf.media import RectangularWaveguide
import disptrans
def test_lossless_waveguide(debug=False):
"""Test lossless WR-2.8 waveguide."""
# Waveguide dimensions
a, b, length = 28 * sc.mil, 14 * sc.mil, 2 * sc.inch
# Full frequency sweep for WR-2.8
freq = Frequency(260, 400, 1401, 'ghz')
# Create an ideal WR-2.8 waveguide
wr2p8 = RectangularWaveguide(freq.copy(), a=a, b=b)
beta = wr2p8.beta.copy() # phase constant
# Create 2 inch long waveguide
waveguide = wr2p8.line(length, unit='m')
# Unpack
f = freq.f.copy()
s21f = waveguide.s[:, 1, 0].copy()
# Calculate space-domain response: single point
x = np.array([length])
s21x = disptrans.freq2distance(f, s21f, beta, x)
# Check distance-domain response
if debug:
print(s21x)
else:
np.testing.assert_almost_equal(np.ones(1), s21x, decimal=3)
# Calculate space-domain response: sweep
x = np.linspace(-length * 10, length * 12, 1401)
s21x = disptrans.freq2distance(f, s21f, beta, x)
# Go back to frequency-domain
fresp = disptrans.distance2freq(x, s21x * np.hamming(len(x)), beta, f)
# Truncate
mask = (265e9 < f) & (f < 395e9)
# Debug
if debug:
import matplotlib.pyplot as plt
plt.figure()
plt.plot(f[mask] / 1e9, unwrap(s21f[mask]), 'k--', label="Original")
plt.plot(f[mask] / 1e9, unwrap(fresp[mask]), 'r', alpha=0.5, label="Recovered")
plt.xlabel("Frequency (GHz)")
plt.ylabel("S21 phase (deg)")
plt.title("S21 phase")
plt.legend()
plt.figure()
plt.plot(f[mask] / 1e9, db20(s21f[mask]), 'k--', label="Original")
plt.plot(f[mask] / 1e9, db20(fresp[mask]), 'r', alpha=0.5, label="Recovered")
plt.xlabel("Frequency (GHz)")
plt.ylabel("S21 magnitude (dB)")
plt.title("S21 magnitude")
plt.legend()
plt.show()
# Check
if not debug:
np.testing.assert_almost_equal(s21f[mask], fresp[mask], decimal=3)
def test_lossy_waveguide(debug=False):
"""Test lossy WR-2.8 waveguide."""
# Waveguide imensions
a, b, length = 28*sc.mil, 14*sc.mil, 2*sc.inch
# Full frequency sweep for WR-2.8 waveguide
freq = Frequency(260, 400, 1401, 'ghz')
# Create an ideal WR-2.8 waveguide
wr2p8 = RectangularWaveguide(freq.copy(), a=a, b=b, rho="au")
beta = wr2p8.beta.copy() # phase constant
# Create 2 inch long waveguide
waveguide = wr2p8.line(length, unit='m')
# Unpack
f = freq.f.copy()
s21f = waveguide.s[:, 1, 0].copy()
# Calculate space-domain response
x = np.linspace(-length*10, length*12, 1401)
s21x = disptrans.freq2distance(f, s21f, beta, x)
# Go back to frequency-domain
fresp = disptrans.distance2freq(x, s21x*np.hamming(len(x)), beta, f)
# Truncate
mask = (265e9 < f) & (f < 395e9)
# Debug
if debug:
import matplotlib.pyplot as plt
plt.figure()
plt.plot(f[mask] / 1e9, unwrap(s21f[mask]), 'k--', label="Original")
plt.plot(f[mask] / 1e9, unwrap(fresp[mask]), 'r', alpha=0.5, label="Recovered")
plt.xlabel("Frequency (GHz)")
plt.ylabel("S21 phase (deg)")
plt.title("S21 phase")
plt.legend()
plt.figure()
plt.plot(f[mask] / 1e9, db20(s21f[mask]), 'k--', label="Original")
plt.plot(f[mask] / 1e9, db20(fresp[mask]), 'r', alpha=0.5, label="Recovered")
plt.xlabel("Frequency (GHz)")
plt.ylabel("S21 magnitude (dB)")
plt.title("S21 magnitude")
plt.legend()
plt.show()
# Check
if not debug:
np.testing.assert_almost_equal(s21f[mask], fresp[mask], decimal=3)
def db10(value):
"""Return power-like value in dB."""
return 10 * np.log10(np.abs(value))
def db20(value):
"""Return voltage-like value in dB."""
return 20 * np.log10(np.abs(value))
def unwrap(value):
"""Unwrap phase."""
return 180 / np.pi * np.unwrap(np.angle(value))
if __name__ == "__main__":
test_lossless_waveguide(debug=True)
test_lossy_waveguide(debug=True)
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