 the program. Within limits, the layout window (F1 box) 2.2.1.2 Objectives helps to layout your circuit for etching. This part is mainly devoted to transmission lines. Knowl- edge of transmission lines is necessary in order to un- 2.2.1.1 Aims derstand how high frequency engineering signals can be efficiently moved from one location to another. For ex- We shall cover the basic principles of transmission lines in ample, the antenna for your domestic TV receiver is usu- ally mounted on the roof and it is therefore necessary to this part, and Smith charts and s-parameters in Section 3. find some means of efficiently transferring the received We will then be in a position to save ourselves much work signals into your house. In the commercial world, it is not and avoid most of the tedious mathematical calculations unusual for a radio transmitter to be situated several hun- involved with radio and microwave engineering. dred metres from a mast-mounted transmitting antenna. The main aims of this chapter are: Here again, we must ensure that minimal loss occurs when to introduce you to various types of transmission lines; the signal is transferred to the antenna for propagation. to explain their characteristic impedances from physical parameters; to provide and also to derive expressions for their 2.2.2 Transmission line basics characteristic impedances; to explain their effects on signal transmission from 2.2.2.1 Introduction to transmission lines physical and electrical parameters; to explain and derive expressions for reflection In this discussion we shall start off using some basic coefficients; terms which are easily understood with sound waves. We Communications Engineering Desk Reference; ISBN: 9780123746481 Copyright © 2001, Ed da Silva. Published by Elsevier Ltd 2001. All rights reserved CHAPTER 2.2 Transmission lines F2 PLOT F1 LAYOUT Points 21 Smith radius 1 Connectors Smith Chart S - parameters Layout window Message Box Smith Chart Connectors F3 PARTS a lumped 1500 b tline 5002 90° file setup c qline 500 130° 