Anything that creates changing electric and/or magnetic fields will produce electromagnetic waves. Accelerating a charge (or charges) is a great way to produce an EM wave.

To produce a radio or TV wave:

• Connect an AC source to two conducting rods.
  
  
• When the voltage is maximum one rod is positively charged and the other is negatively charged. This sets up an electric field similar to that from an electric dipole, so this arrangement is called a dipole antenna.
  
  
• When the voltage passes through zero neither rod is charged but there is a current that produces a magnetic field.
  
  
• These electric and magnetic fields are 90^o out of phase with one another, and their amplitudes fall off as 1/r³. These are called the near field, because they dominate close to the antenna.
  
  
• The oscillating electric and magnetic fields close to the antenna generate EM waves, with electric and magnetic fields oscillating in phase with one another. The amplitude of the fields fall off as 1/r, so they dominate far from the antenna and are known as the far field.
  
  
• For a dipole antenna the intensity of the far fields is given by:

  I(q)

  =

  sin2(q) r2

  
  where q is measured from the axis of the antenna. No energy is radiated along the axis, and the intensity is maximum perpendicular to the axis.