WAVEGUIDE THEORY AND APPLICATIONUpon completion of this chapter the student will be able to:1. Describe the development of the various types of waveguides in terms of their advantages and2. Describe the physical dimensions of the various types of waveguides and explain the effects ofthose dimensions on power and frequency. 3. Explain the propagation of energy in waveguides in terms of electromagnetic field theory. 4. Identify the modes of operation in waveguides. 5. Explain the basic input/output methods used in waveguides. 6. Describe the basic principles of waveguide plumbing. 7. Explain the reasons for and the methods of terminating waveguides. 8. Explain the basic theory of operation and applications of directional couplers. 9. Describe the basic theory of operation, construction, and applications of cavity resonators.10. Describe the basic theory of operation of waveguide junctions.11. Explain the operation of ferrite devices in terms of their applications. INTRODUCTION TO WAVEGUIDE THEORY AND APPLICATION That portion of the electromagnetic spectrum which falls between 1000 megahertz and 100,000megahertz is referred to as the MICROWAVE region. Before discussing the principles and applicationsof microwave frequencies, the meaning of the term microwave as it is used in this module must beestablished. On the surface, the definition of a microwave would appear to be simple because, inelectronics, the prefix "micro" normally means a millionth part of a unit. Micro also means small, whichis a relative term, and it is used in that sense in this module. Microwave is a term loosely applied toidentify electromagnetic waves above 1000 megahertz in frequency because of the short physicalwavelengths of these frequencies. Short wavelength energy offers distinct advantages in manyapplications. For instance, excellent directivity can be obtained using relatively small antennas andlow-power transmitters. These features are ideal for use in both military and civilian radar andcommunication applications. Small antennas and other small components are made possible bymicrowave frequency applications. This is an important consideration in shipboard equipment planningwhere space and weight are major problems. Microwave frequency usage is especially important in thedesign of shipboard radar because it makes possible the detection of smaller targets.