Dipole antennas are cheap, easy to manufacture and install. They are used as tv antennas for example. This is a tutorial that uses an interactive java applet to examine the radiation properties of these types of antennas.
Let us consider the dipole antenna of length 2L at the origin of the spherical coordinate system shown in the figure below.
If we assume that the current flowing in the dipole is along the z axis and is of the form
then the amplitudes of the electric and magnetic components of the field radiated by the dipole in the far field zone may be approximated by the formulas (in free space the intrinsic impedance may be approximated by 120Pi).
The average radiated power density is given by the formula
More on antennas antennas and parabolic reflectors.