In another thread, I answered a question about what is going on in a dipole antenna.
http://forum.allaboutcircuits.com/showthread.php?t=78616
I gave it my best answer, but I still don't understand the radiation part very well.
Can anyone explain how a dipole radiates EM radiation? In the dipole, charges slosh back and forth like a swinging pendulum. During that charge oscillation, energy is exchanged between the electric and magnetic near fields. That much I feel pretty clear about.
But how does the phase of the radiated energy relate to the phase of the moving charges? For example, does the peak of the radiated energy phase correspond to the point where the electric and magnetic fields are equally strong (one growing and the other decaying)? That would be my guess, but I can't back it up. And if so, why is that?
I could guess that if the electric and magnetic fields are sinusoidal in strength over time, the point that they are equally strong would correspond to the point at which they both are changing most rapidly; would that be related to emission of radiation? That would argue that EM radiation comes from the fields themselves, the changing fields, not the charges. Is there any sense to that?
http://forum.allaboutcircuits.com/showthread.php?t=78616
I gave it my best answer, but I still don't understand the radiation part very well.
Can anyone explain how a dipole radiates EM radiation? In the dipole, charges slosh back and forth like a swinging pendulum. During that charge oscillation, energy is exchanged between the electric and magnetic near fields. That much I feel pretty clear about.
But how does the phase of the radiated energy relate to the phase of the moving charges? For example, does the peak of the radiated energy phase correspond to the point where the electric and magnetic fields are equally strong (one growing and the other decaying)? That would be my guess, but I can't back it up. And if so, why is that?
I could guess that if the electric and magnetic fields are sinusoidal in strength over time, the point that they are equally strong would correspond to the point at which they both are changing most rapidly; would that be related to emission of radiation? That would argue that EM radiation comes from the fields themselves, the changing fields, not the charges. Is there any sense to that?