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

MODULE A- INTRODUCTION TO RADAR
C= δθ/ δS = 2π/2πR=1/R
For a radar ray travelling relative to the earth when there is a non-uniform atmosphere present,
the ray will bend more or less relative to the earth, depending upon how much the refractive
index changes with height. Then;
C= δθ/ δS=1/R + δn/ δH
It is sometimes convenient to think of the radar rays travelling in straight lines instead of the
actual curved paths they do follow. We can accomplish this by creating a fictitious earth radius is
different from the true earth’s radius. This effective earth’s radius R’ is given by
1/R’=1/R + δn/ δH
There are various relationships between curvature, earth’s radius, effective earth’s radius, and
refractive index gradient. So it is possible to calculate the actual path a radar ray will follow in
real atmospheric conditions.
4. RADAR TYPES
Radars may be classified in several ways due to the criteria of the classification, e.g. receiving
and transmitting type, purpose of the use, operating frequency band, signal emitting type (pulse-
CW), polarization type. It is also possible to make sub classifications under the main
classification of radars. So major types of radars have been denominated as monostatic, bistatic,
pulse, continuous (CW), Doppler, non-Doppler, weather radar, air surveillance radar, mobile
radar, stationary radar, X-Band, L-Band, C-Band, S-Band, K-Band, single polarization radars,
polarimetric radars, etc. Although our main concern is Doppler weather radars which will be
studied in detail, some brief explanation of major types of the radars are also given below:
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TURKEY RADAR TRAINING 1.0 / ALANYA 2005