# Search results for query: *

1. ### Frequency and energy of EM radiation

If you can, please, give a quantitative description with some examples, like the cosinusoidal functions in my post. Also the introduction of the exact name for each quantity (transferred energy, available power, reactive power, etc.) surely would be another help to understand.
2. ### Frequency and energy of EM radiation

Dear ZapperZ, what you say can intuitively make sense, but it surprises me as well as Chandra Prayaga, maybe because we are lacking some mechanical waves concepts and using a different perspective. When for example Electro-magnetic waves are introduced in a classical approach, the Electric field...
3. ### Meaning of Sommerfeld radiation conditions

I had never seen the multipole expansion, but it seems very useful. Ok for the \mathrm{exp}(+ikr): so, maybe your refer to the original Sommerfeld condition \lim_{r \to \infty} r \left( \displaystyle \frac{\partial \phi}{\partial r} - ik \phi \right) = 0 where \phi is proportional to...
4. ### Meaning of Sommerfeld radiation conditions

Sorry for the string of posts, but the answer may be: because of its symmetry, a point source must radiate the same field in all the possible directions.
5. ### Meaning of Sommerfeld radiation conditions

Here http://www.math.wichita.edu/~deepak/IEMS.pdf (bottom of page 1) it is written what you said. The asymptotic behaviour of a field is showed as \mathbf{E} = \displaystyle \frac{e^{ikr}}{r} \left[ \mathbf{E}_{\infty} + O \left( \displaystyle \frac{1}{r} \right) \right] Even without...
6. ### Meaning of Sommerfeld radiation conditions

the higher orders that disappear as r \to \infty. Ok and thank you. But you are speaking about the source, not the field: who can say that a point source must generate a wave with a spherical (as r \to \infty) wavefront? The wavefront could be an ellipsoid or something else and the radiation...
7. ### Meaning of Sommerfeld radiation conditions

Extension Hello! Instead of opening a new thread, I recover this old, poor one. The first two conditions select a field \mathbf{E}, \mathbf{H} which asymptotically (that is, for r \to \infty) is equal to a spherical wave, because |\mathbf{E}| = O \left(\displaystyle \frac{1}{r} \right)...
8. ### Meaning of Sommerfeld radiation conditions

Hello! Promising that I will not make other new questions in the next days :smile:, I have a doubt about the meaning of a pair of expressions. Sommerfeld's conditions for an electromagnetic field produced by a finite source bounded by a finite volume are: \lim_{r \to +\infty} r|\mathbf{E}|...