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1. ### Group delay with Gaussian pulse

Yes, of course it is (as explained in the document): this is straightforward. Anyway I can't get how "the evolution of the amplitude A(x,t) of the harmonic wave e^{i (k_0 x - \omega (k_0) t)} in (8.7) is governed by the" Schrödinger equation (page 5).
2. ### Group delay with Gaussian pulse

Yes, of course, in fact in my post I wrote the 2nd derivative has to be considered. Ok, I understand. Thank you. Did you follow the whole procedure? I can't get how he obtains a Schrödinger equation describing the amplitude of the (8.7) (page 5). Thanks for this one too. Emily
3. ### Group delay with Gaussian pulse

Hello! Starting from a gaussian waveform propagating in a dispersive medium, is it possible to obtain an expression for the waveform at a generic time t, when the dispersion is not negligible? I know that a generic gaussian pulse (considered as an envelope of a carrier at frequency k_c) can be...
4. ### Group velocity definition

They are both a useful way to represent this phenomenon. As promised, I tried to follow your computations and I agree with them. Apart from the last theoretical discussions (that are anyway interesting), I would like to make a pair of questions about the wave packet itself. - Very often the wave...
5. ### Group velocity definition

Your answers are always very useful and clear. This may be very detailed, but I need some time to understand it. I might ask you some clarifications in the next days! In the meanwhile, thank you :)
6. ### Group velocity definition

Thank you for both your answers! Now the definition of group velocity seems to be less weird.
7. ### Group velocity definition

In the propagation of non-monochromatic waves, the group velocity is defined as v_g = \displaystyle \frac{d \omega}{d k} It seems here that \omega is considered a function of k and not viceversa. But in the presence of a signal source, like an antenna in the case of electro-magnetic wave or a...
8. ### Vector potential components in small loop antenna

First of all thank you for your observations. Good idea switching to Cartesian coordinates: because of the position of the unit vectors \mathbf{u}_\phi^\prime, now we have evidence that \mathbf{A} can only have (in Cartesian coordinates) components only parallel to the (x,y) plane. My problem...
9. ### Vector potential components in small loop antenna

Consider a small, thin loop in the (x,y) plane centered in the origin and with radius a. We are interested in the vector potential \mathbf{A} generated by the loop at a point P(r, \theta, \phi), with 2 \pi a \ll r, so at a great distance (moreover, a \ll \lambda). We need two coordinates...