Q:

Dipole antenna VS. coil for RF transmission or recieving

Correct me if I am wrong, but all RF light waves are created via a changing electric and magnetic field. But when looking at all kinds of radios and RF circuits, this light wave is always made with a simple wire antenna. Why are coils not used instead? Wouldn't a coil of the same length create a stronger magnetic field thereby creating a more efficient 'antenna' that produces RF waves?
I know that there has to be a reason why coils are not used, but I cannot find an explanation. It makes more sense to me to have a coil creating a fluxuating electric/ magnetic field rather than a piece of wire.
Thanks in advance!

A:

Take a look at this picture of a dipole antenna: -

Both electric AND magnetic fields are produced by the antenna.
Magnetic fields are produced by straight wires with current flowing in them i.e. the wire doesn't need to be wound into a coil to produce magnetism.
Now, the physics (well, a bit of it): - 
Space has an impedance of approximately 377 ohms and an antenna has to produce an E field in the right proportion to the H (magnetic) field to maximize convsersion of electrical energy flowing to the antenna into EM power.
The ratio of E field to H field is 377 ohms so trying to produce a bigger H field than is necessary is a waste of time because the impedance will be wrong. See this wiki article for extra reading.

