Chapter 4

Radiated Fields

To be able to calculate the radiated fields of an antenna, we start by calculating the radiated fields of an arbitrary current density. In the next chapter we will make an assessment of this current density for a specific antenna, that is the thin-wire dipole antenna. Then, the radiated fields will be a special case of the general situation described in this chapter. The origin of the calculations is the Maxwell equations, wherein current density and charge density are the sources. By introducing the magnetic vector potential and the Lorentz gauge, we will be able to calculate the radiated fields, based on the current density only.

4.1 Maxwell Equations

The Maxwell equations, in the time-domain, are given by:

4.1 4.1

4.2 4.2

4.3 4.3

4.4 4.4

In these equations, E is the electric field images/c04_I0005.gif, D is the dielectric displacement images/c04_I0006.gif, B is the magnetic induction , H is the magnetic field ...

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