HOW DO ANTENNAS FORM AND RADIATE ELECTROMAGNETIC FIELDS?
As previously mentioned, electric field antennas can be related to capacitors. Consider a simple parallel plate capacitor shown in Figure 2(a). The electric field that occurs when a charge is placed on each of the plates is contained in between the plates. If the plates are spread apart so that they lie in the same plane, the electric field between the plates extends out into space. The same process occurs with an electric field dipole antenna as shown in Figure 2(b). Charges on each part of the antenna produce a field into space between the two halves of the antenna. There is an intrinsic capacitance between the two rods of the dipole antenna as shown in Figure 2(c). Current is required to charge the dipole rods. The current in each part of the antenna flows in the same direction. Such current is called antenna mode current. This condition is special because it results in radiation. As the signal applied to the two halves of the antenna oscillates, the field keeps reversing and sends
