Although radars have become more sophisticated with the advances in technology, it is intended to give a very basic description of the components and workings of a typical radar system. The block diagram that follows is a very simplified version of a radar and must be seen as such.

A simplified version of a radar.

The process begins in the Master Oscillator where an electric pulse of very short duration is generated. The pulse is fed in two directions, one to the transmission side and one to reception. On the transmission side the pulse is fed to a Modulator which produces an electrical pulse of very high voltage. On the reception side it is fed to the Time Base Signal Generator (Saw Tooth Generator) that produces an electron beam which moves from the centre of the screen of the Visual Display Unit (VDU) to its outer edge. The movement of the beam is synchronised with the transmission of the radio wave produced by the transmitter. On the transmission side, the modulator’s pulse is fed to a Magnetron in the Transmitter where a very powerful radio (electromagnetic) wave at a very high frequency is produced and transmitted via a Wave Guide to the Antenna, where it is transmitted into the atmosphere in a predetermined direction. In order to prevent this powerful signal from being fed directly to the receiver, a very fast Transmit/Receive Switch is built into the antenna system, that isolates the receiver during its transmission. The switch then connects the antenna system to a Klystron and Amplifier in the Receiver and isolates the transmitter .

As stated, the radio signal is transmitted into the atmosphere by the antenna along a predetermined path. Because of the atmosphere which absorbs most of the energy in the transmitted signal the signal is weakened tremendously with range. When it encounters an object, a part of the energy is reflected back to the antenna. From the antenna the weakened signal is fed via the transmit/receive switch to the receiver where it is amplified and converted back into an electrical pulse and ultimately fed to the screen of the video display unit (VDU). The VDU of the older type radar systems comprised a cathode ray tube similar to hat of the old TV sets. Around the neck of the cathode ray tubes deflecting coils are fitted which are capable of rotating around the neck The movement of the coils is synchronised with the rotation of the antenna, as is the electron stream produced by the time base generator. When no returning echo is received, the electron beam is suppressed and the screen remains blank. When an echo is received, the receiver measures the time taken from transmission to reception of the signal and with the known speed of the signal determines its range. This information is passed to the VDU and the suppression of the electron beam is lifted briefly at the appropriate distance on the radar screen, thus producing a spot of light on the correct bearing and distance on the radar screen.