0·1 MICROWAVE FREQUENCIES          The term microwave frequencies is generally used for those wavelengths measured in centimeters, roughly from 30 cm to 1 mm (1 to 300 GHz). However, microwave really indicates the wavelengths in the micron ranges. This means microwave frequencies are up to infrared and visible-light regions. In this revision, microwave frequencies refer to those from 1 GHz up to 106 GHz. The microwave band designation that derived from World War II radar security considerations has never been officially sanctioned by any industrial, professional, or government organization. In August 1969 the United States Department of Defense, Office of Joint Chiefs of Staff, by message to all services, directed the use of a new frequency band breakdown as shown in Table 0-1. On May 24, 1970, the Department of Defense adopted another band designation for microwave frequencies as listed in Table 0-2. The Institute of Electrical and Electronics Engineers (IEEE) recommended new micr

What is a Signal? Anything which carries information is a signal.  e.g. human voice, chirping of birds, smoke signals,  gestures (sign language), fragrances of the flowers. Many of our body functions are regulated by  chemical signals, blind people use sense of touch. Bees communicate by their dancing pattern. Modern high speed signals are: voltage changer in a telephone wire, the electromagnetic field emanating  from a transmitting antenna,variation of light intensity in an optical fiber. Thus we see that  there is an almost endless variety of signals and a large number of ways in which signals are carried  from  on place to another place.  2.  Signals: The Mathematical Way A signal is a real (or complex) valued function of one or more real variable(s) .When the function  depends on a single variable, the signal is said to be one-dimensional and when the function depends  on two or more variables, the signal is said to be multidimensional. Examples of a o