UNIT 3 - STEP 4
ELECTROMAGNETIC THEORY AND WAVES
WAVES BEHAVIOR IN GUIDED MEDIUMS AND RADIATION R ADIATION
GRUPO 203058_51
TUTOR: WILMER HERNAN GUTIERREZ
UNAD ELECTRONIC ENGINEERING APRIL 2018 INTRODUCTION
In this work is divided into three parts which are a theoretical part, another mathematical and the other practice through simulation software that helps us understand a little better the subject that is being worked on at the moment
THEORETICAL EXERCISES
1. What is the practical implication associated to a line with only reactive components or only resistive components? When heating the resistive elements could deteriorate the insulation of the cables to be used, which, should be used a larger caliber, while the reactive components are usually sensitive to disturbances and losses due to external fields, which should be used Shielded cabling to protect against all types of environmental interference.
2. In a practical transmission system. What is a good value for the reflection coefficient and the VSWR? Explain. The coefficient of reflection when passing from one medium to another determines the relationship between the incident wave and the reflected one, and in turn the reflection coefficient is closely related to the transmission coefficient. the coefficient of reflection is obtained based on the conservation of voltage and current and the ohm law in a phasor Vswr is a bidirectional ordinary transmission line which can propagate in two directions. This relationship between the maximum voltage and the minimum voltage of a standing wave in a transmission line, therefore, has no units. It depends a lot on the variation of the existing waves is a transmission line, but mainly, of the reflected wave. the limit values of vswr are from 1.1 to 1.6 3. What occurs with the voltage and current in a line with the following conditions: line terminated in its characteristic impedance, line terminated in a short and line terminated in an open? When the line terminated in its impedance the voltage is adsorbed by the load, when the line ends in a short circuit there is no load that adsorbs the incident voltage, so it is reflected with the same amplitude and polarity and adds to the new incident, producing a maximum effective voltage and when the line terminated in an open there is no charge that adsorbs the incident voltage, so it is reflected with the same amplitude and opposite polarity and the sum of the new incident, producing a zero voltage 4. What is the voltage reflection coefficient and what is an ideal value for a transmission system? If the line is ideal (without losses), the incident signal will reach the end of the line without attenuation and identically, the reflected signal will return to the beginning of the line without attenuation. The Reflection Coefficient is defined as :
=
Where: = Signal incident (propagating in the direction of transmission) = Reflected signal (propagates in the opposite direction).} the ideal values of transmission goes from 1 to 2 5. What is the effect of Lossy line on voltage and current waves?
6. In the Smith Chart identify a = ,a = 0, two resistive loads and two complex loads. You have to assume the characteristic impedance.
PRACTICAL EXERCISES
= = +
1. A lossless transmission line has a characteristic impedance of and the load at the end of the line has an impedance of Using the Smith Chart, find:
.
a. Reflection coefficient (magnitude and phase), and the VSWR. b. The input impedance if the line is
.
long.
c. The length of the line, necessary to make the input impedance real and the value of the impedance in this point. Data:
= = + =. = −+ ) − = (( ++ )+ =.∡−.° = +|− ||| = +−||..|| =. ) = ++( ( ) + ()+ ( . ) = (+ ) + ( . ) =.+.
= =. =
= =
2. A transmission line has the following parameters:, and
. It has a generator supplying
and in series with a resistance of
impedance of Data:
. Find the input voltage and current.
= = =. = = = =
,
,
at
. The load has an
+ =√ + = + + ∗ = . + ∗ =− − = +− =−. = −. − =.+. = −
3. A lossless transmission line has a . If it and the wavelength is . Find and probe with the smith chart: a. Input impedance.
b. Reflection coefficient. c. VSWR Data;
= =– = =
long
= = =. = −+ = ((−− )− ) + =.∡−.° = +−|||| = +|− |..|| =. ) = ++( ( ) − (−) +)( . ) = (+ ( . ) =.+.
== +
= . = =.+ = =?
4. A transmission line of length has an input impedance . Using the Smith Chart, find the load impedance if . Data:
Clear
) = ++( ( ) ] = [ (()− ) − = [(+)([.(.) −()]+−)] =+.
= − = = . 5. A load
is connected to a transmission line with . The line is . Find the input impedance and at least two line lengths where the input impedance is real. Use the Smith Chart to Solve the exercise.
in group solve the following practical exercise Using the software Smith V4.0, found in the practice learning environment, solve the next exercises and explain each step of the simulation. 1. For the following input impedance and load impedance, find the wavelength necessary to get a real input impedance.
. = − =
. = − =
. = − =
. = − =
CONCLUSIONS
Understanding the use of software is a fundamental part for the development of activities Knowing the equations for the development of the activities in a timely manner makes the solution to the established problems a bit easier to solve Knowing and understanding the theoretical part of the problems is a key part to obtain a faster solution
BIBLIOGRAPHY http://blogcomunicacionesmoviles.blogspot.com.co/2012/11/vswr-voltage-standingwave-ratio-y-dtf.html http://www.oocities.org/uniteciec/ondas_reflejadas.htm
