Step4 _katherin.docx

TEORIA ELECTROMAGNETICA Y ONDAS

STEP 4 - TO ANALYZE THE WAVES BEHAVIOR IN GUIDED MEDIUMS AND RADIATION

KATHERIN SANCHEZ SANCHEZ CC: 1047971813

TUTOR: WILLIAM MAURICIO SAENZ GRUPO: 203058_66

UNIVERSIDAD NACIONAL ABIERTA Y A DISTANCIA ESCUELA DE CIENCIAS BÁSICAS, TECNOLOGÍA E INGENIERÍA

MEDELLIN 2018

Activities to develop

Each student in the group has to answer the following questions using academic references to support the research:

1. What is the practical implications associated to a line with only reactive components or only resistive components? Las implicaciones que se denen tener cuando se use una linea que contiene elementos resistivos es que La principal consideración que debe tenerse es que una linea que contiene solo elementos resistivos, llega a calentarse bastante, por lo que podría deteriorar el esmalte aislante que recubre dicho cable, por lo que debe utilizarse un cable de mayor calibre.

Mientras que una linea que utiliza solo componentes reactivos, suelen ser mas sensibles a las perturbaciones y a las pérdidas debido a la influencia de campos externos, por lo que deben utilizarse un cableado que sea capaz de apantallar las interferencias del ambiente.

Ver más en Brainly.lat - https://brainly.lat/tarea/9007596#readmore 2. In a practical transmission system. What is a good value for the reflection coefficient and the VSWR? Explain. Reflection coefficient

the reflection coefficient relates the amplitude of the reflected wave with the amplitude of the incident wave. It is usually represented with a {\ displaystyle \ Gamma} \ Gamma (uppercase gamma).

The reflection coefficient is given by: 𝑻=

𝒁𝑳 − 𝒁𝟎 𝒁𝑳 + 𝒁𝟎

the VSWR The standing wave ratio (VSWR) is defined as the ratio of the maximum voltage to the minimum voltage of a standing wave in a transmission line, therefore, it has no units. In terms of voltage, it is the division of the sum of the incident voltage plus the reflected voltage between the difference of the incident voltage minus the reflected voltage. Essentially, the VSWR is a measure of the decoupling of all charges in the radiant system (feeders, jumpers, connectors, antennas, and other devices that are part of the radiant system).

The variation of the VSWR depends very much on the variation of the waves existing in a transmission line, but mainly, of the reflected wave. In practical terms, a hit feeder, a badly made connector, a bad fit on the junction of two connectors or an oxidized antenna port make the impedance of the transmission line vary over its entire length and in turn will make the reflected wave increase, so that, consequently, the value of VSWR will rise

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?

line terminated in its characteristic impedance

The characteristic impedance of a transmission line is the value of the relationship between voltage and current in the line if it is of infinite length or has an impedance equal to its characteristic impedance connected to its terminal, depending on its electrical parameters

z0 = √ (L / C) In such conditions, the characteristic impedance is real, that is, purely resistive and does not depend on the frequency, only on the inductance and distributed capacity and, the latter, in turn on the permittivity of the dielectric line terminated in a short and line terminated in an open When a transmission line is terminated in short circuit or open circuit, there is an impedance inversion, every quarter of a wavelength. For a lossless line, the impedance varies from infinity to zero. However, in a more real situation, where power losses occur, the amplitude of the reflected wave is always smaller than that of the incident wave, except in the termination. Therefore, the impedance varies from some maximum value to some minimum value, or vice versa, depending on whether the line ends in a short or an open circuit.

The input impedance for a line without losses, seen from a transmission line that is terminated in a short or open circuit can be resistive, inductive, or capacitive, depending on the distance that exists from the termination. Phasorial diagrams are generally used to analyze the input impedance of a transmission line because they are relatively simple and give a graphical representation of the relationships between voltage and current phases. The relationships between the voltage and current phase refer to the variations in time. 4. What is the voltage reflection coefficient and what is an ideal value for a transmission system?

The incident voltage in a transmission line has a relationship with the flying reflection voltage which is known as the voltage reflection coefficient 𝑇=

𝑉𝑟 𝑣0 − = 𝑉𝑖 𝑣0 +

5. What is the effect of Lossy line on voltage and current waves?

What is the effect of the line with loss in voltage

For analysis purposes, transmission lines are often considered, without loss, however, there are actually several ways in which energy is lost in a transmission line. There are the losses in the driver, lost by radiation, lost by heating the dialectic, lost by coupling and crown effect

the current waves

it is a direct current that undergoes regular changes of magnitude from a constant value. The changes can be in intensity or tension. These changes or pulses are always in the same direction as the current. That is why all types of alternate currents, whether square, sinusoidal or in the saw are not pulsatory.

In the figure on the right you can see some examples of waves of different periodic currents. The types a, d and e are alternate currents and b, c and f are pulsating.

6. In the Smith Chart identify a 𝒁𝑳 =∝, a 𝒁𝑳 = 𝟎, two resistive loads and two complex loads. You have to assume the characteristic impedance.

Where: 𝑍𝑙 : is the load impedance 𝑍0 : is the characteristic impedance of the stretch 𝑍(𝑧): input impedance to the tráiler

𝜆 4

Choose one of the following problems, solve it and share the solution in the forum. Perform a critical analysis on the group members’ contributions and reply this in the forum. 5. A load 𝒁𝑳 = 𝟑𝟓 − 𝒋𝟔𝟎𝛀 is connected to a transmission line with 𝒁𝟎 = 𝟕𝟓𝛀. The line is 𝒍 = 𝟎. 𝟒𝟓𝝀. Find the input impedance and at least two line lengths where the input impedance is real. Use the Smith Chart to Solve the exercise.

Una carga Z_L = 35-j60Ω está conectada a una línea de transmisión con Z_0 = 75Ω. La línea es l = 0.45λ. Encuentre la impedancia de entrada y al menos dos longitudes de línea donde la impedancia de entrada es real. Usa la tabla de Smith para resolver el ejercicio

Solution: The first step to take is the location of the load impedance in the chart. As you know, the values on the Smith chart are normalized with respect to the impedance of the line, therefore; any impedance value that you want to place in it must be divided by Zo in this way 𝑧 35 60 = −𝑗 = 0.4 − 𝑗 0.8 𝑧0 75 75