Microwave Filters for Communication Systems: Fundamentals, Design and Applications

CHAPTER 1

RADIO FREQUENCY (RF) FILTER NETWORKS FOR WIRELESS COMMUNICATIONS—THE SYSTEM PERSPECTIVE

This chapter is devoted to an overview of communication systems, especially the relationship between the communication channel and other elements of the system. The intent here is to provide the reader with sufficient background to be able to appreciate the critical role and requirements of radio frequency (RF) filters in communication systems. A number of standard texts [1–8] have been referred to in developing a significant portion of this chapter.

The chapter is divided into three parts: Part I presents a simple model of a communication system, the radio spectrum and its utilization, the concept of information, and system link budgets. Part II describes the noise and interference environment in a communication channel, the nonideal amplitude and phase characteristics of the channel, the choice of modulation–demodulation schemes, and how these parameters impact the efficient use of the allocated bandwidths. Part III discusses the impact of system design on the requirements, and the specifications of microwave filter networks in satellite and cellular communication systems.

PART I INTRODUCTION TO A COMMUNICATION SYSTEM, RADIO SPECTRUM, AND INFORMATION

1.1 MODEL OF A COMMUNICATION SYSTEM

Communication refers to the process of conveying information-bearing signals from one point to another that is physically separate. In ancient times, people communicated over long distances by a variety ...