oncepts of connected to ports 3 and 4 without coupling between the matched and unmatched lines. This was followed by sources at port 1 and port 3. It also helps to combine the a thorough discussion of reflection coefficients and inputs or outputs of two amplifiers without mutual in- VSWRs in Section 2.2.11. terference. The unfortunate thing about the ring is that it Section 2.2.12 dealt with the propagation properties is a relatively narrow-band device. of lines and showed how these can be derived from the primary constants of the line. The section also showed how optimum transmission can be achieved. 2.2.15 Summary Section 2.2.13 showed how transmission lines can be used as transformers, impedance matching devices, in- This chapter has provided you with a thorough basic ductive and capacitive reactances which in turn can be knowledge of transmission lines and their properties used to produce filters. Microstrip lines are particularly which you will find very useful in circuit and system useful for making filters at the higher frequencies be- design of radio and microwave systems. You have been cause of their versatility in allowing characteristic im- introduced to many properties of transmission lines in pedance changes to be made easily. There is also a greater this chapter. tendency to use transmission lines as the tuning In Section 2.2.3, you were introduced to some of the elements. more frequently used types of transmission lines. These Section 2.2.14 showed you how transmission lines can included waveguides, coplanar waveguides, coaxial lines, be connected to act as signal couplers. This page intentionally left blank Chapter 2.3 Software defined radio Brad Bannon What Is software-defined radio? translating a wide range of frequencies and bands to that which the data converters themselves can adequately Over the last decade as semiconductor technology has process [1]. improved both in terms of performance capability and SDRs are ideal candidates to be used for multi-carrier, cost, new radio technologies have