Fundamental waveguide characteristics

The principles and parameters discussed in previous sections are applicable to waveguides and microwave devices. However, generally waveguides are used over short distances and losses are minimized. If a dielectric waveguide is used then primary and secondary coefficients such as R, G and a have to be considered. In this text air-filled rectangular waveguides will be discussed.

The part of the electromagnetic spectrum referred to as the microwave region loosely includes the range 1-300 GHz for practical purposes. Microwaves can be used for almost any of the applications for which the lower frequencies are used, but some of the advantages of the shorter waves make them more applicable for certain purposes. The two main advantages of microwaves are that the energy can be focused into narrow beams and that large signal bandwidths are possible.

These microwave bands are especially advantageous for relay sevices such as are used in satellite transmission, telephone relay, oil platform transmission and the broadcasting of commercial radio and television. However, special components and devices are required for operation at microwave frequencies, and one of these, a circulator, is shown in Fig. 7.5. The circulator allows the same microwave antenna to be coupled to the receiver and transmitter. This and other components will be discussed in this chapter.



The purpose of this chapter is to give a basic idea of the various microwave generators and devices which are used in the industry, but initially a knowledge of microwave transmission is necessary.

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