An antenna that is of half wavelength of a signal is a dipole antenna. When a signal is fed to this antenna, it should induce an electron flow. However, it is also said that this electron flow produces high concentrations of electrons on either sides of the dipole alternatively during transmission. Many literature state that it is this electron flow that creates a fluctuating magnetic field around the antenna.

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I would like to now take a second example. Lets take the example of an AC light bulb being lightened by a 230V 50Hz source. The bulb is connected to the AC source through a wire. In this case, does this wire too experience the same effect of alternating concentrations of electrons on its ends? Doesn't the electrons flow continuously from one end of the souse through the light bulb back to the source without having aforementioned "concentrations" on either sides?

If so, I would like to know how the former scenario happens especially in the case of antennas and not for the second scenario.

source I studied : https://www.youtube.com/watch?v=7bDyA5t1ldU


Lets take the example of an AC light bulb being lightened by a 230V 50Hz source

The wavelength of 50 Hz is 6,000 kilometres so any electron bunching will be miniscule to the point of anyone not being able to detect the effect. If the wire were a km long or the lightbulb were maybe a km high then yes, you will start to see this phenomena.

Antennas rely on the signal wavelength being in the same realm as their dimensions to achieve the optimum interface between an electrical feed circuit (aka coax etc.) and the impedance of free space. Take a look at this: -

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Picture is public domain and taken from here.

The signal generator produces a frequency whose wavelength (\$\lambda\$) is twice the length of the antenna (a half wave dipole). This is optimal for a dipole to achieve best conversion of electrical power to electromagnetic radiated power.

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