International Journal of Advanced Engineering, Management and Science (IJAEMS) [Vol-1, Issue-1, April- 2015] ISSN: 2454-1311 Page | 19 A Review on “Weather Surveillance Radar” Abhishek Kumar, Dharmveer Singh 1,2 Department of ECE, JECRC , Jaipur (Raj.), India Abstract— This paper strives to make an impact on Weather radar, also called weather surveillance radar (WSR) and Doppler weather radar, is a type of radar which locates precipitation and estimates its type (rain, snow, hail etc.). Soon after the World War II, surplus radars were used and since then, weather radar has evolved and is now used by national weather services and research departments. Modern weather radars i.e. Doppler radars are capable of detecting the motion of rain droplets in addition to the intensity of the precipitation to determine the structure of storms and their potential to cause severe weather. Hence, it is a key forecasting tool. Weather radars send directional pulses of microwave radiation, on the order of a microsecond long, using a cavity magnetron or klystron tube connected by a waveguide to a parabolic antenna and receives the return signals from particles in the air on the order of a millisecond, which is a thousand times longer than the pulse duration. Keywords- Cavity Magnetron, Cavity Resonators, Control Head, Klystron, Radar. I. INTRODUCTION Mostly, people plan their leisure time ahead according to the weather and so for the sake of weather forecasting, radar is a significant concept. It’s a classic example of an electronic engineering system that utilizes many of the specialized elements including propagation, electromagnetic scattering, detection, information extraction and data processing. The name reflects the importance placed by the early workers in this field on the need for a device to detect the presence of a target and to measure its range. Invented just before World War II for military purpose, it has since been applied to many areas, an important one being weather monitoring. A weather radar detects rain in the atmosphere by emitting pulses of microwave and measuring the reflected signals from the raindrops. Through detecting raindrops in the atmosphere, the weather radar is a very effective tool for monitoring severe weather such as tropical cyclones, thunderstorms and heavy rain. Doppler radar has become increasingly popular in recent years. The Doppler principle can be explained by noting the change in pitch of an ambulance siren. The pitch heightens as the ambulance approaches and lowers as it departs. In other words, the faster the ambulance approaches, the higher will be the pitch. The Doppler radar has also been applied in healthcare, such as fall detection and fall risk assessment, for nursing or clinic purpose. 1. Basic Radar Before proceeding to the working of weather radar, let us first understand the meaning of RADAR which stands for Radio Detecting And Ranging as indicated by the name. Radar is an electromagnetic (EM) system for the detection and location of reflecting objects like aircrafts, people, ships and natural environment. It operates by radiating energy into space and detecting the echo signal reflected from a target. By detecting these signals target location and related information can be determined. It can operate in snow, haze, fog, rain and darkness. Block Diagram of Fundamental Radar System A transmitter (in the upper left portion of the figure) generates EM signal (such as a short pulse of sine wave) to provide sufficient energy to detect a target, be easily modulated to faithfully produce the desired waveforms, generate a stable signal of tunable bandwidth, high efficiency and high reliability. The generated signal is radiated into space by an antenna. The radar antenna is a distinctive and important part of any radar, it has parabolic shape for great directivity of transmitted signals in the direction of target. A portion of the transmitted energy is intercepted by the target and reradiated in many directions. The re-radiation directed back towards the radar is collected by the radar antenna, which delivers it to a receiver. There it is recorded by data recorder and then processed to detect the presence of the target and determine its location using processor and radar display.