# Copyright (c) 2008-2026 Tim Molteno (tim@elec.ac.nz)

#

# Plot of reflection coefficient vs antenna length for a fixed base height.

#

import monopole

import numpy as np

import pylab as plt

from antenna_util import reflection_coefficient

lengths = np.linspace(0.2, 5.0, 270)

reflections = []

z0 = 50

for l in lengths:

freq = 134.5

z = monopole.impedance(freq, base=0.5, length=l)

reflections.append(reflection_coefficient(z, z0))

plt.plot(lengths, reflections)

plt.xlabel("Antenna length (m)")

plt.ylabel("Reflection coefficient")

plt.title("Reflection coefficient vs length (base_height=0.5m)")

plt.grid(True)

plt.show()

plt.savefig("reflection_coefficient.png")