def test_connect_nport_2port(self):
freq = rf.Frequency(1, 10, npoints=10, unit='GHz')
# create a line which can be connected to each port
med = rf.DefinedGammaZ0(freq)
line = med.line(1, unit='m')
line.z0 = [10, 20]
for nport_portnum in [3,4,5,6,7,8]:
# create a Nport network with port impedance i at port i
nport = rf.Network()
nport.frequency = freq
nport.s = npy.zeros((10, nport_portnum, nport_portnum))
nport.z0 = npy.arange(nport_portnum)
# Connect the line to each port and check for port impedance
for port in range(nport_portnum):
nport_line = rf.connect(nport, port, line, 0)
z0_expected = nport.z0
z0_expected[:,port] = line.z0[:,1]
npy.testing.assert_allclose(
nport_line.z0,
z0_expected
)
def to_network(self,
skrf_frequency: rf.Frequency,
name: str = 'front-face') -> rf.Network:
"""Convert into a skrf Network.
Assume the scattering parameters of the network are the same
for all the frequencies of the network.
Parameters
----------
skrf_frequency : :class:`skrf.frequency.Frequency`
Frequency of the network (for compatibility with skrf)
name : string, optional
name of the network. Default is 'front-face'
Returns
-------
network : :class:`skrf.network.Network`
"""
network = rf.Network(name=name)
network.s = np.tile(self.s, (len(skrf_frequency), 1, 1))
network.z0 = self.z0
network.frequency = skrf_frequency
# take into deembbeding if necessary
if self._deemb != 0:
# create a coaxial line of length = deemb
coax_media = rf.DefinedGammaZ0(network.frequency, z0=self.z0)
# Create a circuit in which we connect the inverse of the coaxial
# lines to each ports
coax1 = coax_media.line(d=self._deemb, unit='m', name='line1').inv
coax2 = coax_media.line(d=self._deemb, unit='m', name='line2').inv
coax3 = coax_media.line(d=self._deemb, unit='m', name='line3').inv
coax4 = coax_media.line(d=self._deemb, unit='m', name='line4').inv
port1 = rf.Circuit.Port(network.frequency, 'port1', z0=self.z0)
port2 = rf.Circuit.Port(network.frequency, 'port2', z0=self.z0)
port3 = rf.Circuit.Port(network.frequency, 'port3', z0=self.z0)
port4 = rf.Circuit.Port(network.frequency, 'port4', z0=self.z0)
cnx = [
[(port1, 0), (coax1, 0)],
[(coax1, 1), (network, 0)],
[(port2, 0), (coax2, 0)],
[(coax2, 1), (network, 1)],
[(port3, 0), (coax3, 0)],
[(coax3, 1), (network, 2)],
[(port4, 0), (coax4, 0)],
[(coax4, 1), (network, 3)],
]
network = rf.Circuit(cnx).network.copy()
return (network)
def setUp(self):
self.freq = rf.Frequency(start=1, stop=2, npoints=101)
self.media = rf.DefinedGammaZ0(self.freq)
def RLC2S_LPF(g,
Wstart,
Wstop,
npoints=1001,
dB_limit=-100,
ladder_type="LC",
W=True,
plot=False):
"""
Function to plot S21 and S11 from g parameters.
Main purpose of this function is to ensure that the g values are indeed correct.
@param g: g parameters as a list [g_0, g_1, ..., g_{n+1}]
@param start: starting frequency (avoid 0)
@param stop: stop frequency
@param npoints: number of points for plotting purpose
"""
if not ladder_type == "LC":
warn("ladder_type must be LC for the time being")
return
freq = rf.Frequency(start=Wstart / (2 * pi),
stop=Wstop / (2 * pi),
unit="Hz",
npoints=npoints)
tl_media = rf.DefinedGammaZ0(freq, z0=1, gamma=1j * freq.w / rf.c)
# GND and port elements
gnd = rf.Circuit.Ground(freq, name="gnd")
port1 = rf.Circuit.Port(freq, name="port1", z0=g[0])
port2 = rf.Circuit.Port(freq, name="port2", z0=g[-1])
g = g[1:-1]
# L and C elements for LC ladder
ckt_elements = []
ind_flag = True # L starts first
for i in range(len(g)):
ckt_elements.append(tl_media.inductor(
g[i], name=str(i))) if ind_flag else ckt_elements.append(
tl_media.capacitor(g[i], name=str(i)))
ind_flag = not ind_flag # toggle between inductors and cpacitors
# node connections
cnx = []
for i in range(int(len(g) / 2) + 1):
if i == 0:
cnx.append([(port1, 0), (ckt_elements[i], 0)]) # starting
elif i == int(len(g) / 2):
if int(len(g)) % 2 == 0: # ending ... even order case
cnx.append([
(ckt_elements[2 * i - 2], 1),
(ckt_elements[2 * i - 1], 0),
(port2, 0),
])
else: # ending ... odd order case
cnx.append([
(ckt_elements[2 * i - 2], 1),
(ckt_elements[2 * i - 1], 0),
(ckt_elements[2 * i], 0),
])
cnx.append([
(ckt_elements[2 * i], 1),
(port2, 0),
])
else: # in between
cnx.append([
(ckt_elements[2 * i - 2], 1),
(ckt_elements[2 * i - 1], 0),
(ckt_elements[2 * i], 0),
])
# GND connections ... same for even and odd cases
gnd_cnx = []
for i in range(int(len(g) / 2) + 1):
if i == 0:
gnd_cnx.append((gnd, 0))
elif i == int(len(g) / 2):
gnd_cnx.append((ckt_elements[2 * i - 1], 1))
else:
gnd_cnx.append((ckt_elements[2 * i - 1], 1))
cnx.append(gnd_cnx)
# create a circuit out of all the elements and connections
cir = rf.Circuit(cnx)
ntw = cir.network
freq = 2 * pi * ntw.frequency.f if W else ntw.frequency.f
if plot:
title = ("Transfer Functions vs Angular Frequency"
if W else "Transfer Functions vs Frequency")
xlabel = "w" if W else "f"
ylabel = "|H(w)|" if W else "|H(f)|"
rf.plotting.plot_rectangular(
freq,
cutoff(rf.mathFunctions.complex2dB(ntw.s[:, 1, 0]), dB_limit),
x_label=xlabel,
y_label=ylabel,
title=title,
show_legend=True,
label="S21",
)
rf.plotting.plot_rectangular(
freq,
cutoff(rf.mathFunctions.complex2dB(ntw.s[:, 0, 0]), dB_limit),
label="S11",
)
if not (port1.z0[0] == port2.z0[0]):
warn("port2 and port2 impedances are not equal")
s_ax = plt.gca()
s_ax.axvspan(0, 1, facecolor="r", alpha=0.2)
s_ax.axhspan(0, -3, facecolor="g", alpha=0.2)
# s_ax.axvspan(0, 1.6, facecolor="r", alpha=0.2)
plt.show()
return freq, ntw.s[:, 0, 0], ntw.s[:, 1, 0]
