Electrical Communication is a free textbook on the basics of communication technology. See the editorial for more information....


Review Questions

1. Why is there an increasing tendency to use cables for communication?

2. How are telephone cables constructed? What is a quad?

3. Discuss the variations of R, L, C, and O of a cable with temperature and frequency.

4. Discuss the variations of cable attenuation with temperature and frequency.

5. What are the characteristics of the classical "distortionless line"?

6. Briefly discuss the history of loading.

7. In what way is a loaded cable similar to a filter?

8. How are echo effects and loading related?

9. Compare the characteristic impedances and propagation constants of loaded and non-loaded cables.

10. In general, to what types of circuits is loading applied?

11. Discuss the construction of loading coils.

12. Discuss the installation of loading coils.

13. What is flutter, and what is its cause?

14. The location of impedance irregularities, such as a reversed loading coil, is discussed on page 255. Why not use the methods of page 75?

15. What assumption regarding velocity is made in equation 26?

16. Are coaxial cables balanced or unbalanced? From what important circuits do they differ in this respect?

17. What types of dielectrics are used in coaxial cables?

18. What are the characteristic impedances of typical coaxials? Compare with lines and cables.

19. Describe a typical submarine cable.

20. Describe the type of loading used on transoceanic cables.

21. Are transoceanic cables used for telephone purposes? If so, name one. If not, why are they not used?

22. What is meant by the dominant mode of a wave guide?

23. Distinguish between the TE mode and the TM mode.

24. On page 266 it is stated that for certain conditions a wave guide may flash across. How is it possible for this to occur?

25. How is it possible for the apparent, or phase, velocity in a wave guide to be greater than the velocity of an electromagnetic wave in free space?



Last Update: 2011-05-18