Uh, it’s not an electromagnetic field, it’s an electromagnetic wave, the wavelength of which,
Blah, blah, yada, yada, so on and so forth.
Forest for the trees. It is in fact an electromagnetic field because you can't have one without the other (hence, electro-magnetic) and it travels out in every direction (hence, field). This is in fact how electricity is generated: by moving a wire through a magnetic field. From Hoover Dam to Koetsu to the transformer in every component ever made this is how it works. Its a field because its three dimensional. Your precious "wave" is nothing more than a flat 2D representation of a three dimensional field.
Everyone else: Forest for the Trees is a prime example of the difference between memorizing words and understanding concepts. Understanding concepts you can actually explain them so others understand them as well. Memorizing words all you can do is correct (when you shouldn't) people actually using correctly the words you never were able to understand yourself.