TYPES OF RADAR SYSTEMS

For further information on the construction and discernible video signals. Because the radar frequen- operation of microwave component, review NEETS ties are very high and difficult to amplify, a super- Module 11, Microwave Principles, NAVEDTRA 172- heterodyne receiver is used to convert the echoes to a 11-00-87. lower frequency, called the intermediate frequency (IF), which is easier to amplify. Duplexer TYPES OF RADAR SYSTEMS The duplexer is essentially an electronic switch that permits a radar system to use a single antenna to both transmit and receive. The duplexer must connect the antenna to the transmitter and disconnect the antenna from the receiver for the duration of the trans- mitted pulse. The switching time is called receiver recovery time, and must be very fast if close-in targets are to be detected. Antenna System The antenna system routes the pulse from the transmitter, radiates it in a directional beam, picks up the returning echo, and passes it to the receiver with a minimum of loss. The antenna system includes the antenna, transmission lines, and waveguide from the transmitter to the antenna, and transmission lines and waveguide from the antenna to the receiver. Because of different design parameters, no single radar set can perform all the many radar functions required for military use. The large number of radar systems used by the military has forced the develop- ment of a joint-services classification system for accurate identification of radars. Radar systems are usually classified according to their specific function and installation vehicle. The joint-service stand- ardized classification system divides these broad cate- gories for more precise identification. Since no single radar system can fulfill all the requirements of modern warfare, most modern war- ships, aircraft, and shore installations have several radar sets, each performing a specific function. A shipboard radar installation may include surface- search and navigation radars, a 3-D radar, an air- search radar, and various fire-control radars. Receiver Table 1-2 is a listing of equipment identification indicators. You can use this table and the radar nom- The receiver accepts the weak RF echoes from the enclature to identify the parameters of a particular antenna system and routes them to the indicator as radar set. 1-7