def print_result(x, f, accepted):
log_base, log_length = x
base_height = np.exp(log_base)
length = np.exp(log_length)
if accepted:
print("Optimium base_height=%fm, h=%fm, impedance=%s Ohms" % \
(base_height, length, monopole.impedance(freq, base_height, length)))
else:
print("Local_minimum=%fm, h=%fm, impedance=%s Ohms" % \
(base_height, length, monopole.impedance(freq, base_height, length)))
def target(x):
global freq, target_impedance
base_height = np.exp(x[0]) # Make it positive
length = np.exp(x[1]) # Make it positive
if (length > 10.0):
return 100
try:
z = monopole.impedance(freq, base_height, length)
return reflection_coefficient(z, z0=target_impedance)
except RuntimeError as re:
return 100
def target(x):
global freq
base_height = np.exp(x[0]) # Make it positive
length = np.exp(x[1]) # Make it positive
z = monopole.impedance(freq, base_height, length)
return reflection_coefficient(z, z0=50.0)
#
import monopole
import scipy.optimize
import numpy as np
from antenna_util import reflection_coefficient
# A function that will be minimized when the impedance is 50 Ohms
# We convert the height and antenna length to positive
# numbers using exp. because otherwise the antenna will lie
# below ground and cause an error in simulation.
def target(x):
global freq
base_height = np.exp(x[0]) # Make it positive
length = np.exp(x[1]) # Make it positive
z = monopole.impedance(freq, base_height, length)
return reflection_coefficient(z, z0=50.0)
# Starting value
freq = 134.5
x0 = [-2.0, 0.0]
# Carry out the minimization
log_base, log_length = scipy.optimize.fmin(target, x0)
base_height = np.exp(log_base)
length = np.exp(log_length)
print "Optimium base_height=%fm, h=%fm, impedance=%s Ohms" % \
(base_height, length, monopole.impedance(freq, base_height, length))
#
# 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")
#
# 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")
def target(x): global freq base_height = np.exp(x[0]) # Make it positive length = np.exp(x[1]) # Make it positive z = monopole.impedance(freq, base_height, length) return reflection_coefficient(z, z0=50.0)
# Automatically tune antenna # import monopole import scipy.optimize import numpy as np from antenna_util import reflection_coefficient # A function that will be minimized when the impedance is 50 Ohms # We convert the height and antenna length to positive # numbers using exp. because otherwise the antenna will lie # below ground and cause an error in simulation. def target(x): global freq base_height = np.exp(x[0]) # Make it positive length = np.exp(x[1]) # Make it positive z = monopole.impedance(freq, base_height, length) return reflection_coefficient(z, z0=50.0) # Starting value freq = 134.5 x0 = [-2.0, 0.0] # Carry out the minimization log_base, log_length = scipy.optimize.fmin(target, x0) base_height = np.exp(log_base) length = np.exp(log_length) print "Optimium base_height=%fm, h=%fm, impedance=%s Ohms" % \ (base_height, length, monopole.impedance(freq, base_height, length))
#
# Automatically tune antenna
#
import monopole
import scipy.optimize
import numpy as np
from antenna_util import reflection_coefficient
# A function that will be minimized when the impedance is 50 Ohms
# We convert the height and antenna length to positive
# numbers using exp. because otherwise the antenna will lie
# below ground and cause an error in simulation.
def target(x):
global freq
base_height = np.exp(x[0]) # Make it positive
length = np.exp(x[1]) # Make it positive
z = monopole.impedance(freq, base_height, length)
return reflection_coefficient(z, z0=50.0)
# Starting value
freq = 134.5
x0 = [-2.0, 0.0]
# Carry out the minimization
log_base, log_length = scipy.optimize.fmin(target, x0)
base_height = np.exp(log_base)
length = np.exp(log_length)
print("Optimium base_height={}m, h={}m, impedance={} Ohms".format(base_height, length, monopole.impedance(freq, base_height, length)))