Electromagnetics: Plane Wave Propagation, Unknown Medium

In summary, the conversation discusses determining the conductivity, wavelength, and phase velocity of a medium based on wave attenuation and reflection measurements conducted at 1MHz. It is mentioned that the intrinsic impedance of the medium is known, as well as the skin depth. The question then arises of determining the type of medium based on these values and if there is a method for doing so using the phase angle of the intrinsic impedance. It is mentioned that if the conductivity is zero, the intrinsic impedance will be real, and there are formulas relating the intrinsic impedance and skin depth to other variables such as angular frequency and conductivity. From the given data, the question can be answered.
  • #1
Captain1024
45
2

Homework Statement


Based on wave attenuation and reflection measurements conducted at 1MHz, it was determined that the intrinsic impedance of a certain medium is
gif.latex?28.1%5Cangle%2045%5E%5Ccirc%20%5C%20%28%5COmega%29.gif
, and the skin depth is 2m.
Determine:
a) The conductivity of the medium
b) The wavelength in the medium
c) The phase velocity.

Answer to a) 2.52x10^-2 S/m

Homework Equations


N/A

The Attempt at a Solution


I need to know what type of medium this wave is traveling through. We learned five types in class: Perfect Dielectric, Low-Loss Dielectric, Quasi-Conductor, Good Conductor, Perfect Conductor. The way I learned to determine the type of medium was by using a ratio of
gif.latex?%5Cfrac%7B%5Cepsilon%27%27%7D%7B%5Cepsilon%27%7D.gif
. Where
gif.latex?%5Cepsilon%27%27%20%3D%20%5Cfrac%7B%5Csigma%7D%7B%5Comega%7D.gif
, and
gif.latex?%5Cepsilon%27%20%3D%20%5Cepsilon.gif
. How can I determine this ratio if one of the terms in the ratio is unknown (namely, the conductivity ##\sigma##)? The angle ##45^\circ## was mentioned in class when we were talking about good conductors. And, the phase angle of the intrinsic impedance is ##45^\circ##. But, is there a method for determining medium type using phase angle of the intrinsic impedance?

-Captain1024
 
Last edited by a moderator:
  • #3
Captain1024 said:

Homework Statement


Based on wave attenuation and reflection measurements conducted at 1MHz, it was determined that the intrinsic impedance of a certain medium is
gif.latex?28.1%5Cangle%2045%5E%5Ccirc%20%5C%20%28%5COmega%29.gif
, and the skin depth is 2m.
Determine:
a) The conductivity of the medium
b) The wavelength in the medium
c) The phase velocity.

Answer to a) 2.52x10^-2 S/m

Homework Equations


N/A

The Attempt at a Solution


I need to know what type of medium this wave is traveling through. We learned five types in class: Perfect Dielectric, Low-Loss Dielectric, Quasi-Conductor, Good Conductor, Perfect Conductor. The way I learned to determine the type of medium was by using a ratio of
gif.latex?%5Cfrac%7B%5Cepsilon%27%27%7D%7B%5Cepsilon%27%7D.gif
. Where
gif.latex?%5Cepsilon%27%27%20%3D%20%5Cfrac%7B%5Csigma%7D%7B%5Comega%7D.gif
, and
gif.latex?%5Cepsilon%27%20%3D%20%5Cepsilon.gif
. How can I determine this ratio if one of the terms in the ratio is unknown (namely, the conductivity ##\sigma##)? The angle ##45^\circ## was mentioned in class when we were talking about good conductors. And, the phase angle of the intrinsic impedance is ##45^\circ##. But, is there a method for determining medium type using phase angle of the intrinsic impedance?

-Captain1024
If and only if conductivity is zero, the intrinsic impedance η is real. There is a formula relating η to μ, ε, ω and conductivity γ. Here η has real and imaginary parts.
There is another formula relating skin depth δ to ω, μ and γ. δ also has real and imaginary parts here.
From the given data (ω and the real and imaginary parts of η) you can answer the question.
 
Last edited:

What is plane wave propagation?

Plane wave propagation refers to the behavior of electromagnetic waves as they travel through a uniform and unbounded medium. In this type of propagation, the electric and magnetic fields of the wave are perpendicular to the direction of propagation and are constant in amplitude and phase.

What is an unknown medium in electromagnetics?

An unknown medium in electromagnetics refers to a material or environment where the properties of the medium are not known or are difficult to determine. This could include the presence of multiple materials, varying densities, or complex structures that affect the propagation of electromagnetic waves.

How do electromagnetic waves propagate through an unknown medium?

Electromagnetic waves propagate through an unknown medium by following the laws of electromagnetics, including Maxwell's equations. The waves interact with the medium, which can cause changes in their amplitude, phase, and direction of propagation. The properties of the medium such as its permittivity and permeability also play a role in how the waves propagate.

What factors can affect the propagation of electromagnetic waves in an unknown medium?

Several factors can affect the propagation of electromagnetic waves in an unknown medium, including the properties of the medium, the frequency of the wave, and the angle of incidence. Other factors such as reflections, refractions, and diffractions can also play a role in how the waves propagate through the medium.

What are some real-world applications of plane wave propagation in unknown mediums?

Plane wave propagation in unknown mediums has various applications in fields such as telecommunications, radar technology, and medical imaging. In telecommunications, the behavior of electromagnetic waves in unknown mediums is crucial for signal transmission and reception. In radar technology, understanding how waves propagate through different mediums is essential for target detection and tracking. In medical imaging, plane wave propagation is used to visualize the internal structures of the human body using various imaging techniques such as X-rays and MRI.

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