Properties of RG-58

This example demonstrates how to use skrf’s to explore some properties of Coax (RG-58). This is done through the media package which provides basic transmission line models. Specifically, the coax is created using by DistributedCircuit.

import matplotlib.pyplot as plt
import numpy as np

import skrf as rf
from skrf.media import DistributedCircuit
from skrf.plotting import func_on_all_figs as foaf

%matplotlib inline

rf.stylely()



# define a frequency object from a vector
freq = rf.F.from_f(np.logspace(0,6,1001), unit='hz')

# create a Media object for RG-58, based on distributed ckt values
rg58 = DistributedCircuit(
    frequency = freq,
    C =93.5e-12,#F/m
    L =273e-9,  #H/m
    R =0,#53e-3,   #Ohm/m
    G =0,       #S/m
    )


# loop thru values of resistivity plot various quantities
for k in (0,.1,1,10,100):
    rg58.R = k*1e-3

    plt.figure(0)
    plt.ylabel('Phase Velocity (m/us)')
    plt.title('Phase Velocity')
    plt.loglog(freq.f_scaled, rg58.v_p*1e-6, label=rf'{k:.1e} $m \Omega/m $')

    plt.figure(1)
    plt.ylabel('Real($Z_0$)')
    plt.title('Characteristic Impedance (Real)')
    plt.loglog(freq.f_scaled, rg58.z0.real, label=rf'{k:.1e} $m \Omega/m $')

    plt.figure(2)
    plt.ylabel('-Imag($Z_0$)')
    plt.title('Characteristic Impedance (Imag)')
    plt.plot(freq.f_scaled, -1*rg58.z0.imag, label=rf'{k:.1e} $m \Omega/m $')

    plt.figure(3)
    plt.ylabel(r'Real($\gamma$)')
    plt.title('Propagation Constant (Real)')
    plt.plot(freq.f_scaled, rg58.alpha, label=rf'{k:.1e} $m \Omega/m $')

    plt.figure(4)
    plt.ylabel(r'Imag($\gamma$)')
    plt.title('Propagation Constant (Imag)')
    plt.plot(freq.f_scaled, rg58.beta, label=rf'{k:.1e} $m \Omega/m $')





foaf(freq.labelXAxis)
foaf(plt.tight_layout)
foaf(plt.legend)
foaf(plt.loglog)

plt.tight_layout()

/home/docs/checkouts/readthedocs.org/user_builds/scikit-rf/checkouts/latest/.venv/lib/python3.10/site-packages/matplotlib/cbook.py:1762: ComplexWarning: Casting complex values to real discards the imaginary part
  return math.isfinite(val)
/home/docs/checkouts/readthedocs.org/user_builds/scikit-rf/checkouts/latest/.venv/lib/python3.10/site-packages/matplotlib/cbook.py:1398: ComplexWarning: Casting complex values to real discards the imaginary part
  return np.asarray(x, float)