EMFT - ECE
Transmission Lines
Practice questions from Transmission Lines.
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IncorrectA lossless transmission line is terminated with a load of .
If the average incident power on the line is 10 mW, then the average power delivered to the load (in mW, rounded off to one decimal place) is ________.
Given:
Reflection coefficient,
Average Power delivered to Load,
Alternate Solution:
Given:
Consider a lossless transmission line terminated with a short circuit as shown in the figure below. As one moves towards the generator from the load, the normalized impedances , and (indicated in the figure) are_______.
Normalized impedance
A lossless transmission line with characteristic impedance is terminated with an unknown load. The magnitude of the reflection co-efficient is . As one moves towards the generator from the load, the maximum value of the input impedance magnitude looking towards the load (in ) is ________.
The S-parameters of a two port network is given as
with reference to . Two lossless transmission line sections of electrical lengths and are added to the input and output ports for measurement purposes, respectively. The Sparameters of the resultant two port network is
Let us evaluate and first at
(a) :
(b) :
Here,
Hence,
From previous discussion in ,
(looking at options (a) is correct)
A transparent dielectric coating is applied to glass to eliminate the reflection of red light . The minimum thickness of the dielectric coating, in , that can be used is ________. (rounded off to two decimal places).
For no reflection, impedance must be matched. Hence, acts like a quarter wave impedance transformer.
So,
(i)
(ii) For impedance matching,
Here,
Hence, for minimum distance,
So,
The standing wave ratio on a lossless transmission line terminated in an unknown load impedance is found to be 2.0. The distance between successive voltage minima is 30 cm and the first minimum is located at 10 cm from the load. can be replaced by an equivalent length and terminating resistance of the same line. The value of and , respectively, are
Given
As we know that,
Now, distance between successive voltage minima
Also, for minima,
At , 1st minima,
Here,
Going through options,
satisfy this
identity, hence option (b) and (c) are correct.’
The following circuit(s) representing a lumped element equivalent of an infinitesimal section of a transmission line is/are
