Radar Systems for Technicians
Combining historical insight and technical information, this text takes the reader as far back as original World War II concepts to illustrate the logical reasoning behind state-of-the-art radar designs.
TABLE OF CONTENTS Radar Systems for Technicians
Chapter 3: Logarithms, DeciBels, and Power
This is a practical book for use by technicians or engineers who need to know everyday radar equipment theory of operation and maintenance methods. It is not intended to be a source for a mathematics course, and it is written with the assumption that the reader has foundation knowledge in Algebra, Geometry, Trigonometry, Physics, alternating-current mathematics, direct-current mathematics, and fundamental electronic theory. Nevertheless, everyday work in radar does require frequent use of logarithms and deciBels. Still further, the remainder of this book will frequently refer to quantities in deciBels. The use of deciBels must therefore be reviewed before proceeding with any further discussion.
The DeciBel
Is a measurement tool, originally devised by Alexander Graham Bell. Since the Bel portion of the word is derived from Bell s name, the B is always capitalized, even when the word is abbreviated to its common form, dB. The deci portion of the word is related to powers of ten, as the dB is ten times the value of a base-10 logarithm. In latter days, binary circuitry has precipitated the use of base-2 logarithms, but these are rarely, if ever, used in connection with test equipment measurements.
Logarithms
Radar equipment measurements require frequent calculations of gain and attenuation. In earlier times, electronic calculators were not available, and these gain or attenuation measurements required time-consuming multiplication and division. These operations were greatly simplified by the use of logarithms. To add two logarithms achieves a result which is the log of a multiplication product. In subtraction of...
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