How can ellipticity angle be negative.

In summary, the concept of plane wave elliptical polarization states that if the Ellipticity angle is positive, it is a Left Hand Circular polarization (LHC), and if the Ellipticity angle is negative, it is Right Hand Circular polarization (RHC). However, the issue arises when trying to physically draw a negative Ellipticity angle, as both a_eta and a_epsilon (which are used in the equation for calculating the angle) are just lengths and cannot be negative. This is explained further in the "Engineering Electromagnetics" book by Ulaby.
  • #1
yungman
5,718
240
In plane wave elliptical polarization, the book said if the Ellipticity angle is possitive, it is a Left Hand Circular polarization(LHC). If Ellipticity angle is negative, it is Right Hand Circular polarization(RHC).

My question is how can Ellipticity angle be negative?

http://en.wikipedia.org/wiki/Polarization_%28waves%29

Can anyone show a picture of negative Ellipticity angle?

In case this sounds ridiculous, attached is the scan of the paragraph from the "Engineering Electromagnetics" by Ulaby. I have to scan in two part to fit the size limit. First is Ulaby1 and then Ulaby2.

Thanks
 

Attachments

  • Ulaby1L.png
    Ulaby1L.png
    46.7 KB · Views: 565
  • Ulaby2L.png
    Ulaby2L.png
    47 KB · Views: 686
Last edited:
Physics news on Phys.org
  • #2
I don't see what is the problem with a negative ellipticity angle.
The sign of the arcus tangens is not fixed by it's argument, it can be either positive or negative. To decide which one to choose, you have to look at the polarisation of the wave.
 
  • #3
DrDu said:
I don't see what is the problem with a negative ellipticity angle.
The sign of the arcus tangens is not fixed by it's argument, it can be either positive or negative. To decide which one to choose, you have to look at the polarisation of the wave.

The question is how to draw a negative ellipticity angle physically?
[tex]\chi\;=\;\tan^{-1} \frac {a_{\eta}}{a_{\epsilon}}[/tex]
Both are just length and is never negative.
 

1. What is ellipticity angle?

Ellipticity angle is a measure of the elliptical shape of an object or orbit. It is the angle between the major axis and minor axis of the ellipse.

2. How is ellipticity angle calculated?

Ellipticity angle is calculated using the eccentricity of an ellipse, which is the ratio of the distance between the foci to the length of the major axis. It can be calculated using the formula: ε = √(1 - (b/a)^2), where a is the length of the major axis and b is the length of the minor axis.

3. Why can ellipticity angle be negative?

Ellipticity angle can be negative because it is a measure of the orientation of an ellipse. A negative value indicates that the ellipse is tilted in the opposite direction as compared to a positive value.

4. What does a negative ellipticity angle indicate?

A negative ellipticity angle indicates that the object or orbit is more elongated in the opposite direction of the angle. For example, if the angle is -30 degrees, the object or orbit is more elongated in the direction perpendicular to the -30 degree angle.

5. Can ellipticity angle be greater than 90 degrees?

No, ellipticity angle cannot be greater than 90 degrees. This is because it is a measure of the angle between the major and minor axis of an ellipse, and an angle greater than 90 degrees would mean that the minor axis is longer than the major axis, which is not possible for an ellipse.

Similar threads

Replies
23
Views
9K
Replies
2
Views
1K
Replies
1
Views
544
Replies
8
Views
9K
Replies
1
Views
2K
Replies
3
Views
448
  • Programming and Computer Science
Replies
1
Views
1K
Replies
4
Views
2K
Replies
1
Views
1K
  • Advanced Physics Homework Help
Replies
2
Views
2K
Back
Top