Read somewhere about polarization

In summary, polarization refers to the way a material reacts to an electric field and can be defined as the change in charge distribution. There are different types of polarization, including dipoles, ionic contribution, and electronic contribution, which can be influenced by the frequency of the incident electric field. In wireless communications, polarization plays a crucial role in determining the efficiency of signal transmission and reception. Different types of polarization, such as linear, circular, and elliptical, can be used depending on the specific application.
  • #1
dervast
133
1
Hi i need to read somewhere about polarization. What polariation is.. Why we need it? What types of polarization exist and what are the differences.. and so on
 
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  • #2
Here and here you go...

feel free to ask more clarification, if you need.

marlon
 
  • #3
using a simple vocabularium, one could define polarization as the "way" a material reacts when you apply an incident electric field onto it.

Reacts means (and this is the clue) the change in charge distribution. Like for example the way the electron cloud will change its structure because of this incident E-field.

this E-field has a frequency and depending on that value, you get different contributions to the polarization. Ie, different mechanism react to the incident E-field like dipoles, ionic contribution, electronic contribution...

Another classical example is this : suppose you have 5 + charges and 5 - charges that are randomly distributed in a medium. the net charge is zero. If you apply a voltage onto this medium, the - charges will go to the positive side (electrode) and the + charges wil go to the negative side. Now you do have a net charge in the medium, you see ?

marlon
 
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Thx i ll read your interesting links.. I am asking because we are using polarization in wireless communications.. and he polarization seems to be a factor that alters somehow the attributes of the signals/
 
  • #5
dervast said:
Thx i ll read your interesting links.. I am asking because we are using polarization in wireless communications.. and he polarization seems to be a factor that alters somehow the attributes of the signals/
Polarization is important in wireless communications. This technology comes from one that has been developed since 19th century, radio communications. When radio waves are generated, the polarity of the electric field defines the polarity of the antenna. The electric field is perpendicular (orthogonal) to the magnetic field in a linearly polarized antenna.

Here is a http://www.hp.com/rnd/images/pdf_html/antennas_figure7.jpg [Broken] example of horizontal versus vertical linear polarization (They are showing the orientation of the electric field). A receiving antenna ought to be of the same polarity as the transmitting antenna to receive the maximum signal. That does not mean you cannot use a horizontal antenna to receive a vertically polarized radio wave or vice versa. I've done it.. However it is not as efficient as the signal is attenuated. Both of these antennas radiate linearly polarized waves.

Other kinds of polarization are circular or more generally elliptical. In circular polarization, the orientation of both the electric field and magnetic field rotate through 360 degrees. Depending on which way the field rotates, a circularly polarized wave may be clockwise or counterclockwise. marlon's second ref is a good technical discussion of what I have given.

[edited by Russ on request]
 
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1. What is polarization?

Polarization is a phenomenon that occurs when light waves, or other types of waves, vibrate in a specific direction. This results in the waves being restricted to a single plane of oscillation.

2. How does polarization affect light?

Polarization causes light to behave differently, depending on its orientation. For example, polarized sunglasses are designed to block light waves that are horizontally polarized, which reduces glare and improves visibility.

3. What causes polarization?

Polarization can be caused by various factors, such as reflection, refraction, and scattering. When light waves interact with a surface, they can become polarized due to the orientation of the molecules in the surface.

4. How is polarization used in technology?

Polarization is used in various technologies, such as LCD screens, 3D glasses, and polarizing filters. In LCD screens, polarization is used to control the amount of light that passes through the liquid crystals to create images. In 3D glasses, polarization is used to separate different images for each eye, creating a 3D effect. And in polarizing filters, polarization is used to reduce glare and improve image quality.

5. Can polarization be reversed?

Yes, polarization can be reversed by passing light waves through a polarizing filter in the opposite orientation. This process is called polarization reversal or depolarization. It is used in some technologies, such as 3D movie screens, to switch between different images for each eye.

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