"""
.. currentmodule:: skrf.media.device
========================================
device (:mod:`skrf.media.device`)
========================================
Device is a generic n-port microwave device class to create common Network.
Device Class
---------------
.. autosummary::
:toctree: generated/
Device
Example Devices
---------------
.. autosummary::
:toctree: generated/
MatchedSymmetricCoupler
Hybrid
QuadratureHybrid
Hybrid180
DualCoupler
"""
from abc import ABCMeta, abstractproperty
import numpy as np
from numpy import exp, sqrt
from .. import mathFunctions as mf
from ..network import connect
[docs]
class Device:
"""
A n-port microwave device
Parameters
-----------
media : skrf.media.Media
"""
__metaclass__ = ABCMeta
[docs]
def __init__(self, media):
self.media = media
@abstractproperty
def ntwk(self):
"""
the network representation of a given device
"""
return None
[docs]
class MatchedSymmetricCoupler(Device):
"""
A Matched Symmetric Coupler
The resultant ntwk port assignment is as follows:
* 0 - insertion
* 1 - transmit
* 2 - coupled
* 3 - isolated
"""
[docs]
def __init__(self, media, c=None, t=None, t_phase=0, phase_diff=0,
nports=4, *args, **kw):
Device.__init__(self, media=media, **kw)
if c is None and t is None:
raise ValueError('Must pass either `c` or `t`')
if nports not in [3,4]:
raise ValueError('nports must be 3 or 4')
self.phase_diff = phase_diff
self.t_phase = t_phase
self.i = 0
self.nports=nports
if c is not None:
self.c = c
if t is not None:
self.t = t
[docs]
@classmethod
def from_dbdeg(cls, media, db, deg=0, *args,**kw):
r"""
Create a coupler in terms of couping(dB) and phase offset(deg)
Parameters
-----------
media : skrf.media.Media Object
db : number or array-like
the magnitude of the coupling value (in dB), sign dont matter
deg : number or array-like
phase offset between the transmit and coupled arms. defined
as : coupled arm = transmit arm +phase offset
\*args,\*\*kw: passed to self.__init__()
"""
c = mf.db_2_mag(-1*abs(db))
return cls(media=media, c=c, phase_diff=deg, **kw)
@property
def c(self):
return self._c
@c.setter
def c(self,c):
self._c = c
t_rad = mf.degree_2_radian(self.t_phase)
c_rad = t_rad + mf.degree_2_radian(self.phase_diff)
self._t = np.sqrt(1- np.abs(c)**2)*exp(1j*t_rad)
self._c = c*exp(1j*c_rad)
@property
def t(self):
return self._t
@t.setter
def t(self,t):
t_rad = mf.degree_2_radian(self.t_phase)
c_rad = t_rad + mf.degree_2_radian(self.phase_diff)
self._t= t*exp(1j*t_rad)
self._c = np.sqrt(1- np.abs(t)**2)*exp(1j*c_rad)
@property
def ntwk(self):
a = self.media.match(nports=4)
a.s[:,0,1] = a.s[:,1,0] = a.s[:,3,2] = a.s[:,2,3] = self.t
a.s[:,0,2] = a.s[:,2,0] = a.s[:,3,1] = a.s[:,1,3] = self.c
a.s[:,0,3] = a.s[:,3,0] = a.s[:,1,2] = a.s[:,2,1] = self.i
if self.nports ==3:
match = self.media.match()
a = connect(a,3,match,0)
return a
[docs]
class Hybrid(MatchedSymmetricCoupler):
"""
A 3dB Coupler of given phase difference
"""
[docs]
def __init__(self, media, t_phase=180,phase_diff=0, *args, **kw):
c = 1/sqrt(2)
MatchedSymmetricCoupler.__init__(self,media=media, c=c,
phase_diff=phase_diff,
t_phase=t_phase,**kw)
[docs]
class QuadratureHybrid(MatchedSymmetricCoupler):
"""
A 3dB Coupler with 90deg phase diff between transmit and coupled arms
"""
[docs]
def __init__(self, media,t_phase=0, *args, **kw):
c = 1/sqrt(2)
MatchedSymmetricCoupler.__init__(self,media=media,c=c,t_phase=t_phase,
phase_diff=-90, **kw)
[docs]
class Hybrid180(Device):
"""
180degree hybrid
This device can be used to combine two signals in and out of phase,
or as a divider, with outputs in or out of phase.
The resultant ntwk port assignment is as follows:
* 0 - sum (A+B)
* 1 - input A
* 2 - input B
* 3 - delta (A-B)
http://www.microwaves101.com/encyclopedias/hybrid-couplers
"""
[docs]
def __init__(self, media, nports=4, *args, **kw):
Device.__init__(self, media=media, **kw)
self.nports = nports
@property
def ntwk(self):
a = self.media.match(nports=4)
for m,n in [(0,1),(1,0),(2,0),(0,2),(3,2),(2,3)]:
a.s[:,m,n]=-1j
for m,n in [(3,1),(1,3)]:
a.s[:,m,n]=1j
a.s = a.s*1/sqrt(2)
if self.nports ==3:
match = self.media.match()
a = connect(a,3,match,0)
return a
[docs]
class DualCoupler(Device):
"""
Pair of back-to-back directional couplers
Ports are as follows:
* 0 : insertion of coupler 1
* 1 : insertion on coupler 2
* 2 : coupled on coupler 1
* 3 : coupled on coupler 2
"""
[docs]
def __init__(self, media, c1=1/sqrt(2), c2=None, c1kw=None,c2kw=None): # noqa: B008
if c2kw is None:
c2kw = {}
if c1kw is None:
c1kw = {}
Device.__init__(self,media=media)
if c2 is None:
c2= c1
self.c1 = MatchedSymmetricCoupler(media=media,c=c1,nports=3,**c1kw)
self.c2 = MatchedSymmetricCoupler(media=media,c=c2,nports=3,**c2kw)
@property
def ntwk(self):
c1ntwk = self.c1.ntwk
c2ntwk = self.c2.ntwk
ntwk = connect(c1ntwk,1,c2ntwk,1)
ntwk.renumber([0,1,2,3],[0,2,1,3])
return ntwk