Where are the magnetic poles in an electromagnetic wave?

Question

An electromagnetic wave is usually illustrated with two sine wave shaped fields, one for the electric field and one for the magnetic field. As in the picture below:

But as how I understand magnetism, it consists of two poles, north and south (alternatively described with field lines, with a direction, where north and south connects). So to focus only on the magnetic field (the red, B) in an electromagnetic wave; where are the poles located in such a sine wave (the red part)? Is only one of the poles illustrated, such that another sine wave could be added for the other pole?

Update: In this video, Maxwell's second equation is described as the field lines in the magnetic field is always connected (north and south pole) - how these field lines are organized in a wave is what I don't understand.

Later in the same video, the fields emitted from an antenna, are illustrated as "bubbles of fields" - quite different from how the "arrows/vectors" are illustrated in my picture above.

Field lines from the video:

Answer 1

Magnetic fields do not only arise from magnetic poles. For example, they can also be created by electric currents, and the resulting magnetic field lines circle around the wire, without having an "end" at a magnetic pole. See the diagram below for an illustration.

_{Image from HyperPhysics}

Alternately, it is possible to have a changing electric field and magnetic field without any magnetic poles (or electric charges) nearby at all. This is what happens in an electromagnetic wave. Note also that the arrows in your diagram are representatives of the magnetic (and electric) fields at points along the $z$-axis; similar fields exist at all points in a given plane perpendicular to the axis of propagation. (See the diagram below for an illustration of this.) So if you want to think of "field lines", they extend in long horizontal lines from infinity to infinity parallel to the $y$-axis in your diagram.

Answer 2

After some more googling and time spent watching different explanations, I think I have got a better understanding.

This one in 2D shows the electric field propagating to the right. Its distance and time on the x-axis. It also shows that the electric field, mostly are not sine waves (as they typically are visualized). The magnetic field is perpendicular to the electric field - but I think it is a bit strange in this illustration, since the electric field probable is a "plane" and not a "thin line". It is explained here that the electric field can have arbitrary shape, it all depends on how it was created. That the electric field is like a "sine wave" is said to be a misconception in that video. From No, Changing Electric Fields DON'T Cause Magnetic Fields; The Real Origin of Electromagnetic Waves.

That explanation for the shape of the electric field makes sense to me. Especially since an electric field is radiated anytime we e.g. power on a circuit board, as explained in Veritasium - How electricity actually works

But this was only in 2D, and it does not really explain the magnetic field, other than that it is perpendicular to the electric field.

But this picture from wikipedia says little more about the fields in 3D, when radiated from an antenna, especially the magentic field (the red, B).

This is actually not so different from how the fields are organized around a wire carrying electric current. As in this picture: .