training course on weather radar systems - RTC, Regional Training ...

MODULE A- INTRODUCTION TO RADAR
2. RADAR THEORY
2.1.The history of radar
Radar term is the abbreviation of RAdio Detection And Ranging, i.e. finding and positioning a
target and determining the distance between the target and the source by using radio frequency. This
term was first used by the U.S. Navy in 1940 and adopted universally in 1943. It was originally
called Radio Direction Finding (R.D.F.) in England.
We can say that, everything for radar started with the discovering of radio frequencies, and
invention of some sub components, e.g. electronic devices, resulted invention and developing of
radar systems. The history of radar includes the various practical and theoretical discoveries of the
18 th , 19 th and early 20 th centuries that paved the way for the use of radio as means of
communication. Although the development of radar as a stand-alone technology did not occur until
World War II, the basic principle of radar detection is almost as old as the subject of
electromagnetism itself. Some of the major milestones of radar history are as follows:
• 1842 It was described by Christian Andreas Doppler that the sound waves from a
source coming closer to a standing person have a higher frequency while the
sound waves from a source going away from a standing person have a lower
frequency. That approach is valid for radio waves, too. In other words, observed
frequency of light and sound waves was affected by the relative motion of the
source and the detector. This phenomenon became known as the Doppler effect.
• 1860 Electric and magnetic fields were discovered by Michael Faraday.
• 1864 Mathematical equations of electromagnetism were determined by James Clark
Maxwell. Maxwell set forth the theory of light must be accepted as an
electromagnetic wave. Electromagnetic field and wave were put forth
consideration by Maxwell.
TURKEY RADAR TRAINING 1.0 / ALANYA 2005 5