# Chapter 13 Transmission lines¶

## Example 13.1 Page no 483¶

In [2]:
#Given
f= 450.0*10**6

#Calculation
lamda = 984/f
len =0.1*lamda

#Result
print"feet long conductors would be considered as the transmission line ",round(len*10**6,3),"ft"

feet long conductors would be considered as the transmission line  0.219 ft


## Example 13.2 Page no 484¶

In [4]:
#Given
lamda = 2.19

#Calculation
len = (3/8.0)*lamda

#Result
print"The pyhsical length of the transmission line ",round(len,2),"feet"

The pyhsical length of the transmission line  0.82 feet


## Example 13.3 Page no 492¶

In [5]:
#Given
len = 165
attn_100ft = 5.3
pin = 100
attn_ft = 5.3/100.0

#Calculation
total_attn = attn_ft * len
pout = pin *0.1335

#Result
print"The total attenuation of the cable is ",total_attn,"dB"
print"Output power is ",pout,"W"

The total attenuation of the cable is  8.745 dB
Output power is  13.35 W


## Example 13.4 Page no 494¶

In [7]:
#Given
len =150
C =13.5
Z0 =93
f =2.5*10**6
attn_100ft =2.8

#Calculation
L =C*Z0**2
td =(L*C)**0.5
theta = ((360)*188.3)/(1/f)
attn_ft = attn_100ft/100.0
total_attn = attn_ft*150

print"(a) The load impedance required to terminate the the line to avoid the reflections is %d ohm",Z0
print"(b) The equivalent inductance per feet is ",L/10**3,"nh"
print"(c) The time delay introduced by the cable per feet is ",td/10**3,"ns"
print"(d) The phase shift occurs in degrees for the 2.5 Mhz sine wave is ",theta/10**9
print"(e) The total attenuation is ",total_attn,"db"

(a) The load impedance required to terminate the the line to avoid the reflections is %d ohm 93
(b) The equivalent inductance per feet is  116.7615 nh
(c) The time delay introduced by the cable per feet is  1.2555 ns
(d) The phase shift occurs in degrees for the 2.5 Mhz sine wave is  169.47
(e) The total attenuation is  4.2 db


## Example 13.5 Page no 501¶

In [7]:
#Given
vmax= 52.0
vmin= 17.0
Z0 = 75

#calculation
SWR = vmax/vmin
ref_coeff = (vmax-vmin)/(vmax+vmin)
Zl1 = Z0*SWR
Zl2 = Z0/SWR

#Result
print"(a) The standing wave ratio is ",round(SWR,2)
print"(b) Reflection coefficient is ",round(ref_coeff,2)
print"The value of resistive load is ",round(Zl1,2),"ohm or",round(Zl2,2),"ohm"

(a) The standing wave ratio is  3.06
(b) Reflection coefficient is  0.51
The value of resistive load is  229.41 ohm or 24.52 ohm


## Example 13.6 Page no 503¶

In [9]:
#Given
SWR =3.05
ref_pwr =0.2562
pin =30

#calculation
pout = pin -(pin*((SWR-1)/(SWR+1))**2)

#Result
print"The output power of the cable is ",round(pout,3),"W"

The output power of the cable is  22.314 W


## Example 13.7 Page no 508¶

In [13]:
#Given
C =4*10**-12
f =800*10**6
diele = 3.5
h = 0.0625
w = 0.13
t = 0.002

#Calculation
import math
Z0 = 38.8*math.log(0.374/0.106)
Xc = 1/(6.28*f*C)

#Result
print"The charecteristics impedance of the transmission line is ",round(Z0,1),"ohm"
print"The reactance of the capacitor is ",round(Xc,2),"ohm"

The charecteristics impedance of the transmission line is  48.9 ohm
The reactance of the capacitor is  49.76 ohm


## Example 13.8 Page no 508¶

In [19]:
#Given
lamda = (984/800.0)
lamda_8 =lamda/8.0

#Calculation
len = lamda_8*12*(1/3.6**0.5)

#Result
print"The length of the transmission line is ",round(len,3)

The length of the transmission line is  0.972