I've seen some descriptions of electromagnetic waves of late, almost comparing the wiggling an electron (or any charge) to the disturbing of a water surface, and as a result waves are formed that propagate outwards.
My question is thus: why don't EM waves propagate in all directions (like a ripple), or are EM waves in fact doing that?
Electromagnetic waves come in all shapes, sizes, and symmetries.
If you wiggle an electron back-and-forth, you will produce something-like dipole-radiation which is fairly isotropic. The same type of pattern will be produced if you wiggle your finger back-and-forth in water. The strength of the resulting waves will be roughly isotropic, but somewhat smaller in magnitude perpendicular to the direction of your fingers motion.
When you look at these waves from far away, they can be approximated as plane-waves - which might seem directional.
If you include obstacles (e.g. reflectors or absorbers) you can block some aspects of roughly isotropic em waves, to make them directional. This is what happens in a laser or light-bulb, and analogous to what happens to water-waves moving through a channel, or through wave-breakers.
Finally, some types of em-wave sources are intrinsically more directional, like synchrotron/cyclotron radiation. This is comparable to how wind or artificial wave machines produces water waves.
