Introduction of Radar | Radar-Basics, types, working & Applications

In this lecture we are going to learn about,

• Introduction of Radar,
• Type of Radar,
• How Radar is working,
• Working Principle of Radar,
• Components used in the Radar system,
• Application of Radar.

So lets discuss each topic one by one in the detailed manner. but before starting to know about the Radar lets discuss it’s introduction part and then we will move to its technical part.

Introduction:

• Radar is an acronym for “Radio Detection and Ranging”. 
• The term Radio refers to the use of electromagnetic waves with wavelength in the so-called radio waves of the spectrum, which covers a wide range from 10⁴ km to 1 cm.
• Radar is a system used to detect, determine the distance and map the objects such as aircraft and rain.
• Radar uses the strong radio waves for transmitting and receiver listens for reflected echoes. 
• By analyzing the reflected signal, the reflector(object) can be located and identified. 
• Radar can operate in the darkness, haze, fog, rain and snow. it has ability to measure distance with high accuracy in all weather condition.

Working Principle of Radar:

• The electronics principle on which Radar operates is very similar to the principle of sound wave reflection.
• If you shout in the direction of a sound reflecting objects, you will hear an echo. So if you know the speed of sound in the sir, then estimate the distance and general direction of object. 
• Same, Radar uses the electromagnetic energy pulses. The radio frequency energy is transmitted to and reflects form the reflecting object.
• A small portion of the energy is reflected and returns to the Radar system. This returned energy is called an ECHO. 
• Radar system use the echo to determine the direction and distance of the reflecting object.

Block Diagram of Radar:

A practical Radar system requires the seven Basic components as illustrated in the figure:

1. Transmitter:
   • The transmitter makes the electromagnetic wave be sent and adjusts it from the beat train. The transmitter should likewise enhance the sign to a strong level to provide sufficient reach. The wellspring of the transporter wave might be a Klystron, traveling wave Tube (TWT) or Magnetron. Everyone has its own qualities and restrictions.
2. Receiver:
   • The receiver is sensitive to the range of frequencies being transmitted and provides amplification of the returned signal. so as to supply the best range, the receiver must be very sensitive without introducing excessive noise. the flexibility to discern a received signal from background signal depends on the signal-to- noise ratio(S\N).
3. Power Supply:
   • The power supply provides the electric power for all the components. the most important consumer of power is that the transmitter, which can require several kW of power. The actually power transmitted within the pulse could also be much greater than 1 kW.
   • The power supply only must be ready to provide the typical amount of power consumed, not the high power level during the particular pulse transmission.
4. Synchronizer: 
   • The Synchronizer sync the timing for the range determination.
   • Synchronizer sent the signal along with the transmitted signal to know the return sweep and display the signal.
5. Duplexer:
   • This is act like a switch between the transmitter and receiver. 
   • Duplexer place to minimize to use the different antenna for transmitter and receiver.
   •  During the transmission of the pulse, the duplexer will align for the transmitter and after the pulse is sent, the duplexer will align the antenna to the receiver.
   • Duplexer also use to protect the receiver from high power output from the transmitter. 
6. Antenna:
   • The antenna basically acts as a mediator between the system and the air.
   • The antenna takes the Radar pulse from the transmitter and puts it into the air, also takes the reflected wave from the air and puts it into the receiver.
   • Antenna used in the Radar systems are highly directional with low beam width.
7. Display:
   • Display units are basically used to represent the object on the screen to analyze the object easily.
   • there are various types of displays are available in the Radar systems like A-scope, B-scope, PPI, etc.
   • A-scope is the most basic type of display which is used to display the range of the object but can’t provide the direction of the object.
   • PPI is the most common display. It named as  Plan Position Indicator

   • Read More about: Types of Display

Different Types of Radar:

Radar system may be divided into types based on the designed use. This section represent the general characteristics of several commonly used Radar system.

• Air-Defense Radar
• Air Traffic Control Radar
• Fire Control radar or Tracking Radar
• Speed Gauge
• Airborne Radar
• Motor Locating Radar
• Radar Satellites
• weather Radar
• Ground Penetrating Radar

Depending the desired information, radar units must have different qualities and technologies.

On the reason of these different qualities and techniques radar units are classified is:

1. Primary Radar :
   • A primary Radar transmits high frequency signals which are reflected at targets.
   • The received echoes are evaluated. 
   • Primary Radars are transmit and receives echo signal.
2. Secondary Radar:
   1. Secondary Radar  signals are only Transmit the signal. The airplane have a transponder on board to receive an encoded signal of the secondary radar.
   2. Example of secondary radar is IFF (identification of Friend and Foe). 
3. Pulsed Radar:
   • Pulse radar units transit a high frequency impulsive signal of high power. After a longer break in which the echoes can be received follows before a new transmitted signal is sent out.
   • Direction, Distance and sometimes if necessary the altitude of the target can be determined from the measured  antenna and propagation time of the pulse-signal.
4. Continuous-Wave Radar (CW Radar):
   •  CW Radar units transmit a high-frequency signal continuously. The echo signal permanently is received and processed. 
   • The receiver need not be mounted at the same place as the transmitter.

   • Read More about: Frequency Modulated CW radar

5. Unmodulated CW Radar:
   • The transmitter signal of these equipment is constant in amplitude and frequency. These equipment are specialized n speed measuring. Distance cannot measured. 
6. Modulated CW-Radar:
   • The transmitted signal is constant in the amplitude but modulated in the frequency. 
   • It is advantage of these equipment that an evaluation is carried out without reception break and measurement is continuously available.
   • This radar units are used everywhere

Application of Radar:

• Surveillance search Radar in military
• Navigational Radar in military as well as in civil
• Targeting Radar or tracking Radar
• Weather Radar
• Radar proximity fuses
• Radar altimeter
• Air traffic control Radar
• Traffic Radar.
• Monitoring of space vehicles.
• In industry for oil and gas exploration.

Radar Frequencies and its applications: