The Physics and Mathematics of Electromagnetic Wave Propagation in Cellular Wireless Communication

2Characterization of Radiating Elements Using Electromagnetic Principles in the Frequency Domain

Summary

In this chapter we are going to look at the fields produced by some simple antennas and their current distributions in the frequency domain. Specifically, we will observe the fields produced by a Hertzian dipole, a finite sized dipole antenna, and a small loop antenna. We will define the radiating regions of an antenna in terms of the near fields from the far fields and how that is tied to radiation. We will define what is meant by the term radiation and what does it signify and how does it relate to directivity and gain. Examples will be presented to illustrate what are valid near field/far field modeling including analysis of antennas over an imperfectly conducting earth as in a wireless communication environment.

In electrical engineering, we obtain maximum average power from a source with some internal impedance when the connected load impedance equals the complex conjugate of the internal source impedance. This is known as the maximum power transfer theorem. Applying this theorem means that the best we can do is to distribute the source power equally between the source internal impedance and the load impedance; i.e., the efficiency of such a system is at most 50%. Efficiency takes into account the ratio of the dissipated power in the load divided by the source power, while on the other hand the maximum power transfer considers only the magnitude of the dissipated power. ...