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eletromagnetic theory and waves, Ejercicios de Electromagnetismo

Descripción en teoria y ondas basado en las fases 4 de la universidad

Tipo: Ejercicios

2024/2025

Subido el 30/11/2025

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Electromagnetic Theory and Waves
Task 4 – Electromagnetic waves in guided media
Ivan Dario Gonzalez Gonzalez
Group: 202087724_25
Tutor:
DAVID GUSTAVO ROSERO BERNAL
UNIVERSIDAD NACIONAL ABIERTA Y A DISTANCIA
TOCANCIPA CUNDINAMARCA
Noviembre 2025
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Electromagnetic Theory and Waves

Task 4 – Electromagnetic waves in guided media

Ivan Dario Gonzalez Gonzalez

Group: 202087724_

Tutor:

DAVID GUSTAVO ROSERO BERNAL

UNIVERSIDAD NACIONAL ABIERTA Y A DISTANCIA

TOCANCIPA CUNDINAMARCA

Noviembre 2025

Content

Introduction.............................................................................................................. 3

Objectives................................................................................................................ 4

Development of the activity ..................................................................................... 5

Objectives

General Objective:

To analyze the propagation of electromagnetic waves in guided media by calculating

electrical and propagation parameters, interpreting results through mathematical

models, and applying tools such as the Smith chart.

Specific Objectives

To identify and describe the fundamental concepts of transmission lines, including

impedance, VSWR, reflection coefficient, and propagation characteristics.

To solve application exercises involving the calculation of electrical and propagation

parameters in coaxial lines and lossless transmission lines.

To use the Smith chart and complementary digital tools to verify calculated results

and interpret the behavior of guided electromagnetic waves.

Development of the activity

  1. Questions:

a. What do you understand by transmission line? (Rudra, 2020)

A transmission line is a physical structure designed to guide electromagnetic energy

from one point to another. It ensures that signals, especially at high frequencies,

travel efficiently while controlling losses, reflections, and distortions along the path.

b. Define the electrical parameter of transmission lines: Input impedance 𝑍

௜௡

(Jordan, 2016)

The input impedance 𝑍 ௜௡

is the effective impedance seen at the beginning of a

transmission line when it is connected to a load. It depends on the line’s length, its

characteristic impedance, and the load impedance, and it determines how a signal

enters and interacts with the line.

c. Define the electrical parameter of transmission lines: Stationary Wave Ratio

(VSWR). (Voltage Standing Wave Ratio Definition and Formula, 2012)

The VSWR is a measure of how well a transmission line is matched to its load. It

expresses the ratio between the maximum and minimum voltages along the line and

indicates the degree of signal reflection. A VSWR close to 1 means excellent

matching and minimal reflections.

d. Define the electrical parameters of transmission lines: Physical length 𝐿and

electrical length ℓ. (Steer, 2011)

The physical length 𝐿refers to the actual measurable distance of the transmission

line. The electrical length ℓ, on the other hand, describes the line length in terms of

the phase shift it produces on a signal and is usually expressed as a fraction of the

wavelength.

119 × 10

4 𝜋 × 10

ି଻

5.7 × 10

≈ 2.87 × 10

ି ଷ

Loss per unit length (surface model):

≈ 2.8709 × 10

ି ଷ

2 𝜋(6.0 × 10

ିସ

2 𝜋(2.35 × 10

ି ଷ

Conductance per unit length (dielectric, per 𝜎

ln (𝑏/𝑎)

2 𝜋(1 × 10

ି ଵ଺

≈ 4.60 × 10

ି ଵ଺

S/m

Propagation Constant 𝜸 = 𝜶 + 𝒋𝜷

Numerically substituting and evaluating the complex root yields:

 𝛼 = ℜ(𝛾) = 0.0063964408436 Np/m

 𝛽 = ℑ(𝛾) = 2.7321084850 rad/m

Converted:

dB/m

= 8.686 ⋅ 𝛼 ≈ 0.055559 dB/m

dB/km

≈ 55.56 dB/km

Characteristic impedance 𝒁 𝟎

2.73 × 10

ି ଻

4.89 × 10

ି ଵ

Phase Rate 𝒗

𝒑

and wavelength 𝝀

Velocity:

≈ 2.73 × 10

m/s ≈ 0.912ௗ𝑐

Wavelength:

2.7367 × 10

119 × 10

≈ 2.30 m

Skin Depth 𝜹y Comparison with thickness 𝒕

The Skin Depth:

Replacing:

2 𝜋 ⋅ 119 × 10

4 𝜋 × 10

ି ଻

5.7 × 10

≈ 6.11 × 10

ି଺

m

6.11096 𝜇m

GeoGebra:

Calculation of Capacitance per Unit Length in Coaxial Line

Note. The image shows a mathematical operation performed on a calculator to

determine the capacitance per unit length C ́.

Figure 4

Calculation of Inductance per Unit Length in Coaxial Line

Note. The image shows a mathematical operation performed on a calculator to

determine the inductance per unit length L'.

2.2 The type of coax that comes closest is: RG-6/U.

Technical justification:

  1. Its characteristic impedance 75 Ω matches your calculation almost exactly
  1. Its internal driver radius (0.58 mm) is practically the same as yours (0.6 mm).
  2. Its inner radius of the outer driver (2.34 mm) is practically the same as yours

(2.35 mm).

The RG-6/U coaxial cable is one of the most commonly used 75-ohm transmission

lines in radio-frequency and telecommunications applications. It is widely employed

for television distribution, satellite communication, broadband internet, and RF signal

transmission due to its low attenuation over long distances. It consists of a central

copper-clad steel conductor, a dielectric insulator, a metallic shield (normally

aluminum foil and braid), and an outer protective jacket. Its geometry provides an

impedance of 75 Ω, which makes it well suited for high-frequency applications from

a few MHz to several GHz.Because of its relatively small diameter and good

shielding, RG-6/U offers a balance between flexibility, low loss, and high-frequency

performance.

Input Impedance:

The input impedance describes what the source sees looking into the line.

Because the line is long relative to the wavelength, the impedance undergoes

transformations. The calculated value:

௜௡

tan 𝛽ℓ

tan 𝛽ℓ

tan 𝛽ℓ = tan(2.73𝑥1.2) = tan(3.276) ≈ −0.

Figure 5

Graphical Verification of Parameters in Smith's Chart

Note. The image shows the graphical representation in a Smith Letter to validate

theoretical calculations of input impedance, reflection coefficient, and VSWR.

Participation in the forum:

Conclusions

  1. It is understood how electrical parameters (characteristic impedance,

inductance, capacitance, losses and propagation rate) influence the

behavior of electromagnetic waves in guided media, especially in

coaxial lines.

  1. The identification of the RG-6/U cable as the closest to the calculated

dimensions demonstrates how these concepts are applied in real

telecommunications systems, where the correct selection and

adaptation of lines is key to minimize losses and optimize transmission.

  • The use of scientific calculators and interactive software (GeoGebra,

Smith Chart Online) facilita la resolución de problemas complejos,

agiliza el proceso y brinda una representación visual que

complementa la comprensión matemática