How Are Electric and Magnetic Fields Produced in Electromagnetic Radiations?

Click For Summary

Discussion Overview

The discussion revolves around the production of electric and magnetic fields in electromagnetic radiation, specifically addressing their perpendicular orientation and the conditions under which this occurs. Participants explore concepts related to wave propagation, antenna behavior, and the nature of electromagnetic fields in different regions.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions how electric and magnetic fields are produced perpendicular to each other in electromagnetic radiation.
  • Another participant suggests a resource for further understanding, specifically pointing to a module on wave propagation and antennas.
  • A participant notes that the perpendicular relationship of the fields is only true in the 'far field' of a radiator, indicating that closer to the source, the fields can have varying angles.
  • There is a discussion about the nature of fields in different regions, with one participant asserting that in the standing wave region, fields result from various traveling waves in different directions.
  • Another participant mentions that not all modes in waveguides are transverse electromagnetic (TEM), introducing the concept of transverse electric (TE) modes and their relevance near antennas.

Areas of Agreement / Disagreement

Participants express differing views on the behavior of electric and magnetic fields near antennas, with some asserting that the fields can have varying angles close to the source, while others seem to hold the belief that they are always perpendicular in certain conditions. The discussion remains unresolved regarding the specifics of field behavior in various contexts.

Contextual Notes

Limitations include the lack of clarity on the definitions of terms like TEM and TE modes, as well as the conditions under which the fields are considered to be perpendicular. The discussion also does not resolve the mathematical or physical implications of the varying angles of the fields near antennas.

Confused mind
I have encountered a problem that how electric and magnetic fields at perpendicular to each other are produce in electromagnetic radiations?
 
Physics news on Phys.org
Confused mind said:
I have encountered a problem that how electric and magnetic fields at perpendicular to each other are produce in electromagnetic radiations?
This is only the case in the 'far field' of a radiator. Right up close, the fields can have a range of relative angles around, say, a simple antenna. It is only when the fields have settled down at a distance and there is only energy being transferred and not stored (as in a Capacitor or Inductor). A plane EM wave in space is the simplest case.
 
sophiecentaur said:
This is only the case in the 'far field' of a radiator. Right up close, the fields can have a range of relative angles around, say, a simple antenna.

Is that so? Huh. I never knew that. I thought the angle was always 90 degrees.
 
Drakkith said:
Is that so? Huh. I never knew that. I thought the angle was always 90 degrees.
It is when the only wave is a progressive wave. In the standing wave region the fields will be the resultant of various traveling waves in different directions. Also, in waveguides, not all the modes are TEM, there are TE modes too. Coax is always TEM, though.
Near to an antenna you can get different modes which are not TEM and it happens, I think, when you have waves from different parts of the antenna, traveling in different directions.
 
  • Like
Likes   Reactions: berkeman

Similar threads

  • · Replies 11 ·
Replies
11
Views
3K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 10 ·
Replies
10
Views
1K
  • · Replies 9 ·
Replies
9
Views
2K
  • · Replies 3 ·
Replies
3
Views
1K
  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 65 ·
3
Replies
65
Views
6K
  • · Replies 4 ·
Replies
4
Views
3K
  • · Replies 6 ·
Replies
6
Views
1K