# Chapter 7 : Microwave Measurements¶

## Example 7.1 Page No : 273¶

In [1]:
import math

#Given:
c = 3*10**10                   #in cm/s
a = 4                          #in cm
b = 2.5                        #in cm
f = 10*10**9                   #in Hz
d = 0.1                        #distance between 2 minimum power points(in cm)

#calculations
#For TE10 mode:
wl_c = 2*a
wl_o = c/f
wl_g = wl_o/math.sqrt(1-(wl_o/wl_c)**2)
S = wl_g/(math.pi*d)

#---output---#
print 'Voltage standing wave ratio =',round(S,4)

Voltage standing wave ratio = 9.5493


## Example 7.2 Page No : 274¶

In [2]:
import math

#Given:
P_i = 300              #in mW
P_r = 10               #in mW

#calculations
p = math.sqrt(P_r/P_i)
S = (1+p)/(1-p)

#---output---#
print 'Voltage standing wave ratio =',round(S,4)

Voltage standing wave ratio = 1.0


## Example 7.3 Page No : 279¶

In [3]:
import math

#Given:
P_i = 2.5                   #in mW
P_r = 0.15                  #in mW

#---output---#
p = math.sqrt(P_r/P_i)
S = (1+p)/(1-p)
print 'Voltage standing wave ratio =', round(S,4)

Voltage standing wave ratio = 1.6488


## Example 7.4 Page No : 286¶

In [5]:
import math

#Given:
P_i=4.5             #in mW
S=2.                 #VSWR
C=30.                #in dB

#calculations
p=(S-1)/(S+1)
P_f=P_i/(10**(C/10))
P_r=p**2*P_i
#---output---#
print 'Reflected power (in watts) =',P_r

Reflected power (in watts) = 0.5