# Dipole antennas & Conductivity

1. Feb 27, 2012

### oddwolf

Hello!

I have two quick (hopefully) questions about dipole antennas and conductivity.

1) Two dipole antennas are placed at the points (λ/4,0,0) & (-λ/4,0,0) where λ is the wavelength of the emitted radiation. The dipole moments are:

p1 = p_ω *e^(-ωt)
p2 = p_ω *e^(-(ωt-α))

where p_ω is constant, ω is the angular frequency and α is the phase-shift between the two antennas.

And now for the question, if α = 0, do the two antennas amplify or thwart the radiation along the y-axis? the x-axis? How do you rotate the radiation zone 90 degrees?

2)

Suppose you have some sort of conductive body with a charge density of ρ (free particles) at t = 0. qualitatively how do the particles redistribute on the body, and if there's a net charge on the body, where do the charged particles go and what happens? Also what happens with the charge distribution inside the body for t > 0?

My thoughts:

1)

On the first two questions I have a feeling that it amplifies along the y-axis and thwarts the radiaton along the x-axis, why though I am not sure. As for the last question, I suspect you just change the distance between the antennas, but I'd love some explanation on how to.

2)

Pretty lost on this one, would reallui appreciate som help.

Thanks!