Source code for skrf.media.distributedCircuit



'''
.. module:: skrf.media.distributedCircuit
============================================================
distributedCircuit (:mod:`skrf.media.distributedCircuit`)
============================================================



'''

from copy import deepcopy
from scipy.constants import  epsilon_0, mu_0, c,pi, mil
import numpy as npy
from numpy import sqrt, exp, array,tan,sin,cos,inf, log, real,imag,\
         interp, linspace, shape,zeros, reshape

from ..tlineFunctions import electrical_length
from .media import Media, DefinedGammaZ0


from ..constants import INF, ONE, ZERO

[docs]class DistributedCircuit(Media): ''' A transmission line mode defined in terms of distributed impedance and admittance values. Parameters ------------ frequency : :class:`~skrf.frequency.Frequency` object frequency band of the media z0 : number, array-like, or None the port impedance for media. Only needed if its different from the characterisitc impedance of the transmission line. if z0 is None then will default to Z0 C : number, or array-like distributed capacitance, in F/m L : number, or array-like distributed inductance, in H/m R : number, or array-like distributed resistance, in Ohm/m G : number, or array-like distributed conductance, in S/m Notes ---------- if C,I,R,G are vectors they should be the same length :class:`DistributedCircuit` is `Media` object representing a transmission line mode defined in terms of distributed impedance and admittance values. A Distributed Circuit may be defined in terms of the following attributes, ================================ ================ ================ Quantity Symbol Property ================================ ================ ================ Distributed Capacitance :math:`C^{'}` :attr:`C` Distributed Inductance :math:`L^{'}` :attr:`L` Distributed Resistance :math:`R^{'}` :attr:`R` Distributed Conductance :math:`G^{'}` :attr:`G` ================================ ================ ================ The following quantities may be calculated, which are functions of angular frequency (:math:`\omega`): =================================== ================================================== ============================== Quantity Symbol Property =================================== ================================================== ============================== Distributed Impedance :math:`Z^{'} = R^{'} + j \\omega L^{'}` :attr:`Z` Distributed Admittance :math:`Y^{'} = G^{'} + j \\omega C^{'}` :attr:`Y` =================================== ================================================== ============================== The properties which define their wave behavior: =================================== ============================================ ============================== Quantity Symbol Method =================================== ============================================ ============================== Characteristic Impedance :math:`Z_0 = \\sqrt{ \\frac{Z^{'}}{Y^{'}}}` :func:`Z0` Propagation Constant :math:`\\gamma = \\sqrt{ Z^{'} Y^{'}}` :func:`gamma` =================================== ============================================ ============================== Given the following definitions, the components of propagation constant are interpreted as follows: .. math:: +\\Re e\\{\\gamma\\} = \\text{attenuation} -\\Im m\\{\\gamma\\} = \\text{forward propagation} See Also -------- from_media '''
[docs] def __init__(self, frequency=None, z0=None, C=90e-12, L=280e-9, R=0, G=0, *args, **kwargs): super(DistributedCircuit, self).__init__(frequency=frequency, z0=z0) self.C, self.L, self.R, self.G = C,L,R,G
def __str__(self): f=self.frequency try: output = \ 'Distributed Circuit Media. %i-%i %s. %i points'%\ (f.f_scaled[0],f.f_scaled[-1],f.unit, f.npoints) + \ '\nL\'= %.2f, C\'= %.2f,R\'= %.2f, G\'= %.2f, '% \ (self.L, self.C,self.R, self.G) except(TypeError): output = \ 'Distributed Circuit Media. %i-%i %s. %i points'%\ (f.f_scaled[0],f.f_scaled[-1],f.unit, f.npoints) + \ '\nL\'= %.2f.., C\'= %.2f..,R\'= %.2f.., G\'= %.2f.., '% \ (self.L[0], self.C[0],self.R[0], self.G[0]) return output def __repr__(self): return self.__str__()
[docs] @classmethod def from_media(cls, my_media, *args, **kwargs): ''' Initializes a DistributedCircuit from an existing :class:'~skrf.media.media.Media' instance. Parameters ------------ my_media : :class:'~skrf.media.media.Media' instance. the media object ''' w = my_media.frequency.w gamma = my_media.gamma Z0 = my_media.Z0 z0 = my_media.z0 Y = gamma/Z0 Z = gamma*Z0 G,C = real(Y), imag(Y)/w R,L = real(Z), imag(Z)/w return cls(frequency = my_media.frequency, z0 = z0, C=C, L=L, R=R, G=G, *args, **kwargs)
[docs] @classmethod def from_csv(self, *args, **kw): d = DefinedGammaZ0.from_csv(*args,**kw) return self.from_media(d)
@property def Z(self): ''' Distributed Impedance, :math:`Z^{'}` Defined as .. math:: Z^{'} = R^{'} + j \\omega L^{'} Returns -------- Z : numpy.ndarray Distributed impedance in units of ohm/m ''' w = self.frequency.w return self.R + 1j*w*self.L @property def Y(self): ''' Distributed Admittance, :math:`Y^{'}` Defined as .. math:: Y^{'} = G^{'} + j \\omega C^{'} Returns -------- Y : numpy.ndarray Distributed Admittance in units of S/m ''' w = self.frequency.w return self.G + 1j*w*self.C @property def Z0(self): ''' Characteristic Impedance, :math:`Z0` .. math:: Z_0 = \\sqrt{ \\frac{Z^{'}}{Y^{'}}} Returns -------- Z0 : numpy.ndarray Characteristic Impedance in units of ohms ''' return sqrt(self.Z/self.Y) @property def gamma(self): ''' Propagation Constant, :math:`\\gamma` Defined as, .. math:: \\gamma = \\sqrt{ Z^{'} Y^{'}} Returns -------- gamma : numpy.ndarray Propagation Constant, Notes --------- The components of propagation constant are interpreted as follows: positive real(gamma) = attenuation positive imag(gamma) = forward propagation ''' return sqrt(self.Z*self.Y)