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Radar – Definition, Invention, History, Types, Uses, Parts, Working

Radar technology has revolutionized the way we perceive and interact with the world around us. Originally developed for military applications, Radio Detecting and Ranging has found widespread use in various fields, ranging from weather forecasting to aviation, maritime navigation, and even traffic control. Further, this groundbreaking technology enables us to detect and track objects that are otherwise invisible to the naked eye. In this article, we will explore the principles behind radar, its diverse applications, and the immense impact on numerous industries.


More About Radio Detecting and Ranging

A Radar is an electromagnetic sensor, used to detect, locate, track, and recognize different kinds of objects at considerable distances.  It operates by transmitting electromagnetic energy towards objects which is mainly referred as targets that observes the echoes returned from them. It operates in the UHF and microwave range. The targets can be anything such as airplanes, Defense and Civil ships, Space Objects, Automatic Vehicles, or even rain.


Nowadays Radar’s function is not only limited to the location and speed of objects, but they can also be used to detect shapes and sizes of the objects too. Radio Detecting and Ranging is slightly different from optical and infrared sensing devices as it has the capacity to detect faraway things under adverse weather conditions and to find their range, distance with precision.

History of Radio Detecting and Ranging

In the year 1930’s and 1940’s, Radar had gone through a rapid development to meet the requirements of the military. There are many technological forces originated in armed forces and they are also widely employed by armed forces.

Along with this, the Radio Detecting and Ranging found an increasing number of civilian applications mainly air-traffic control, observation of weather, remote sensing of the environment, aircraft and navigation of ship, speed measurement of industrial applications, law enforcement, space surveillance and planetary observation.

Working Principle of Radio Detecting and Ranging

The working principle of Radio Detecting and Ranging is very simple. It transmits electromagnetic power and examines the energy returned back to the target. If the signals are returned again at the position of their source, then an obstacle is in the transmission way.


Radar Systems consist of three Primary Components:-

Components of Radio Detecting and Ranging are a transmitter, a receiver, and a processor


The transmitter generates radio waves, which are then emitted into space in the form of short pulses. These waves travel through the air until they encounter an object in their path.


When the radio waves hit an object, they bounce back or reflect in various directions. Some of these reflected waves are picked up by the radar receiver. The receiver acts as a specialized antenna, designed to capture the weak signals returning from the objects.

The receiver detects the reflected waves and measures the time it takes for them to return. By knowing the speed of radio waves, which is approximately the speed of light, the radar system can calculate the distance between the transmitter and the object. This calculation is based on the time it took for the waves to travel to the object and back to the receiver.

In addition to distance, Radio Detecting and Ranging systems can also measure the Doppler shift of the reflected waves. The Doppler effect refers to the change in frequency that occurs when there is relative motion between the radar system and the object. By analyzing the frequency shift, the radar system can determine the speed at which the object is moving away from or toward the radar.

Furthermore, Radio Detecting and Ranging systems can extract additional information from the reflected waves. By analyzing the properties of the waves, such as their amplitude and phase, the system can gather data about the shape, size, and composition of the detected object. This ability enables radar to differentiate between different types of objects, such as aircraft, ships, or precipitation in weather radar.

Principle of Radar
Principle of Radar


The received signals from radar are processed and analyzed by a dedicated processor. The processor applies various algorithms to interpret the data and extract meaningful information. This information can include the position, velocity, and even the nature of the detected objects.

How Radio Detecting and Ranging Works?

Radar operates based on the following steps:-

How RADAR Works
How RADAR Works


The radar system starts by generating high-frequency radio waves using a transmitter. These waves are typically in the microwave frequency range. The transmitter emits these waves in the form of short pulses, which propagate through space at the speed of light.


The radio waves travel through the atmosphere in straight lines until they encounter an object in their path. When the waves reach the object, they interact with it in various ways, depending on its properties and composition.


Upon encountering an object, a portion of the transmitted waves is reflected back towards the radar system. The amount of energy reflected depends on the object’s size, shape, and composition. Smaller or more smooth objects tend to reflect less energy, while larger or more reflective objects reflect more energy.


The radar system uses a specialized antenna, called a radar receiver, to capture the reflected waves. The receiver is designed to be sensitive to the weak signals returning from the objects. It picks up the reflected waves and converts them into electrical signals.

Time Measurement

The receiver measures the time it takes for the reflected waves to return to the radar system. Since the radio waves travel at the speed of light, the time delay between transmission and reception is directly related to the distance between the radar system and the object. By knowing the speed of light, the system can calculate the distance based on the time delay.

Signal Processing

The received signals are then processed and analyzed by a dedicated processor. Signal processing techniques are applied to extract meaningful information from the received signals. This includes determining the distance, velocity, and other characteristics of the detected objects.

Display and Interpretation

The processed information is displayed on a radar screen or monitor, allowing the operator to visualize and interpret the data. The radar display typically shows the location of detected objects, their relative motion, and additional details such as shape or size if available.

By continuously repeating these steps, the radar system can detect and track multiple objects simultaneously, providing real-time information about their positions, velocities, and other relevant parameters. This information is invaluable in various applications, including aviation, maritime navigation, weather forecasting, defense, and even automotive safety systems.

Essential Parts of Radio Detecting and Ranging

Following are the Essential Parts of Radar:-


The transmitter generates radio frequency (RF) signals, typically in the microwave range, and emits them as short pulses. These pulses carry the energy that will be transmitted into space.


They are the transmission lines for transmission of the radar signals.


The antenna serves as both a transmitter and receiver. It is responsible for radiating the RF pulses into space and capturing the reflected signals from objects. The antenna’s design and characteristics determine the system’s beam shape, radiation pattern, and gain.


The duplexer is a device that allows the radar system to switch between transmitting and receiving modes. It ensures that the transmitted pulse does not damage the sensitive receiver components.


The receiver is responsible for capturing and amplifying the weak signals that are reflected back to the radar system. It converts the received signals from electromagnetic waves into electrical signals that can be processed.

Signal Processor

The signal processor processes the received signals to extract useful information. It performs various tasks such as filtering, amplification, demodulation, and digital signal processing. The signal processor analyzes the received signals to determine the range, velocity, and other characteristics of the detected objects.

Display System

The display system presents the processed radar data in a user-friendly format. It typically includes a radar screen or monitor that shows the position, motion, and other relevant information about the detected objects. The display system may also include controls and user interfaces for operating the radar system.

Control System

The control system governs the operation of the radar system. It includes components such as control interfaces, processors, and software that allow the operator to configure and manage the system parameters, including transmission power, operating frequency, and scanning patterns.

Types of Radio Detecting and Ranging

There are various types of radars:–

Bistatic Radar

Bistatic Radar
Bistatic Radar Principle

Bistatic radar includes Tx-transmitter and an Rx-receiver that is divided through a distance which is equivalent to the distance of the estimated object.

Doppler Radar 

Doppler Radar
Doppler Radar

It is one of the special type of radar which uses the doppler effect in order to generate the data velocity of a target at a particular distance. The application of this radar includes various industries like meteorology, aviation, healthcare etc.

Monopulse Radar

Monopulse Radar
Monopulse Radar

Monopulse radar system compares the received signal using a particular radar pulse next to it by contrasting the signal as observed in various directions else polarizations. Another important to note is that the radars developed in 1960 are Monopulse radars.

Passive Radar

Passive Radar
Passive Radar

The passive radar is designed to notice and follow the targets via processing indications from lighting within the surroundings.

Instrumentation Radar 

Instrument Radar
Instrument Radar Block Diagram

They are designed to test the aircraft, missiles, rockets etc. These radars give different information which includes space, position and time both in the analysis of post-processing and real-time.

Weather Radar

Weather Radar
Weather Radar

These weather radars are used to detect the weather and direction with the help of radio signals via circular or horizontal polarization.

Mapping Radar

Mapping Radar
Mapping Radar

The mapping radar is used to check a large geographical area for the use of remote sensing and geography. These mapping radars are restricted to quite stationary targets because of synthetic aperture radar.

Navigational Radar

Navigational Radar
Navigational Radar

These radars are available with small wavelengths which have the capacity to duplicate from the ground and from the stones. They are mostly used on commercial ships and long-distance airplanes. There are various navigational radars like marine radars which are placed on ships to avoid collision and for navigational purposes.

Pulsed Radar

Pulse Radar Block Diagram
Pulse Radar Block Diagram


They send high power and high-frequency pulses towards the target object then wait for the echo signal from the object before another pulse is sent.

Pulse Doppler 

Pulse Doppler Radar
Pulse Doppler Radar Block Diagram

Pulse doppler transmits high pulse repetition frequency to avoid doppler inexactness. The transmitted signal and the received echo signal are mixed in a detector to get the doppler shift.

Moving Target Indicator


This transmits low pulse repetition frequency to avoid range inexactness. The received echo signals from the object are directed towards the mixer which are mixed with the signal from a stable local oscillator to produce IF signal.

Continuous Wave 

Continuous Wave 
Continuous Wave Radar Block Diagram

This radar does not measure the range of the target, but it measures the rate of change of range by measuring doppler shift of the return signal. The continuous wave radar is mainly used for speed measurement.

Applications of Radio Detecting and Ranging

Below are some of the applications explained:–

Military Applications

This has three major applications as stated below:–

    • It is used for target detection, target recognition weapon control in air defense.
    • It is used in missile system to guide the weapon.
    • Identifying enemy locations on the map.

Air traffic Control

This has three major applications as stated below:–

  • It is used to control air traffic near airports. The air surveillance radar is used to detect and display the position of the aircraft in the airport terminals.
  • It is used to guide the aircraft to land in bad weather condition using precision approach radar.
  • It is used to scan the surface of the airport and ground vehicle positions.

Weather Forecasting

Meteorologists rely on radar technology to monitor weather patterns and predict severe weather events. Weather radars can detect precipitation, such as rain, snow, and hail, and track its movement. By analyzing the data collected, forecasters can issue timely warnings and alerts, helping communities prepare for and mitigate the impact of storms and other weather phenomena.

Maritime Navigation

Radars are indispensable tools for ships and boats, enabling them to navigate safely through waters. Marine radars can detect other vessels, landmasses, and navigational hazards, even in low visibility conditions. By providing information on the location and speed of nearby objects, radar systems assist in collision avoidance and contribute to safer maritime operations.

Ground Traffic Control 

Ground traffic control is used by traffic police to detect the speed of the vehicle, in order to control the movement of vehicles, giving them warnings on other vehicle’s presence or any other obstacles behind them.


This has three major applications as explained below:–

  • It guides the space vehicle for a safe landing on the moon.
  • Observes planetary systems.
  • It detects and track satellites.
  • It monitors the meteors.

The Radio Detecting and Ranging system makes our everyday life safer. From road to air, radars are used to control various things around us. Previously, radars were only used for defense purposes on wars but nowadays radars makes our work easier. It also helpful for research organizations like NASA.

Automotive Industry

Radar-based sensors are becoming increasingly prevalent in the automotive industry, particularly in advanced driver-assistance systems (ADAS) and autonomous vehicles. These sensors enable features like adaptive cruise control, collision avoidance systems, and blind spot detection. By providing real-time data on the vehicle’s surroundings, radar enhances safety and assists in making autonomous driving a reality.

Types of Radar Antennas for Specific Transmission

Here are some commonly used types of radar antenna transmission:

Parabolic Antenna

Parabolic antennas, also known as dish antennas, are widely used in radar systems. They consist of a curved reflector dish with a parabolic shape and a feedhorn located at the focal point. The feedhorn emits or receives the radio waves, while the parabolic reflector focuses the waves into a narrow beam.

Parabolic Antenna
Parabolic Antenna

Parabolic antennas are known for their high gain, which enables long-range transmission and reception. They provide narrow beamwidth and excellent directivity, making them suitable for applications requiring long-distance detection and tracking, such as long-range surveillance radar and space-based radar systems.

Horn Antenna

Horn antennas are widely used in radar systems due to their wide bandwidth, good radiation pattern control, and low noise characteristics. They consist of a flared metallic waveguide that narrows towards the aperture. The radio waves are emitted or received through the aperture of the horn.

Horn Antenna
Horn Antenna

Horn antennas are versatile and are used in various radar applications, including weather radar, short-range radar, and airborne radar. In addition to that, they offer moderate to high gain, depending on the design, and have a relatively wide beamwidth, making them suitable for applications requiring broader coverage.

Slot Antenna

Slot antennas are commonly used in radar systems where a low-profile design is desired. They consist of a narrow slot cut into a metallic surface, which acts as a waveguide to transmit or receive the radio waves. Besides, Slot antennas can be mounted on flat surfaces or integrated into larger structures.

Slot Antenna
Slot Antenna

Slot antennas offer wide bandwidth, simplicity in construction, and low cost. They are often used in radar applications that require compact and low-profile antennas, such as radar altimeters, ground penetrating radar, and some automotive radar systems.

Microstrip Antenna

Microstrip antennas, also known as patch antennas, are compact and lightweight, making them suitable for applications with size and weight constraints. They consist of a metallic patch printed on a dielectric substrate, with a ground plane on the other side.

Microstrip Antenna
Microstrip Antenna

Microstrip antennas are used in various Radio Detecting and Ranging applications, including automotive radar, small radar systems, and satellite communication radar. Basically, they offer moderate gain, a relatively wide beamwidth, and ease of integration into electronic circuits.

Array Antenna

Array antennas are composed of multiple individual antenna elements arranged in a specific configuration. These elements can be driven independently, allowing for beamforming and electronically steering the radar beam.

Array Antenna
Array Antenna

Array antennas offer several advantages, including beam agility, improved target detection, and increased resolution. Accordingly, they are used in advanced Radio Detecting and Ranging systems, such as phased array radar and radar systems requiring electronic scanning and beam agility.

The Future of Radio Detecting and Ranging

As technology continues to advance, Radio Detecting and Ranging systems are poised to undergo further evolution. Researchers are exploring new frequency bands, such as millimeter-wave radar, for enhanced resolution and accuracy. Moreover, advancements in signal processing and data analysis are enabling Radio Detecting and Ranging systems to extract more information from the received signals, leading to improved object detection and classification capabilities.

Furthermore, the integration of Radio Detecting and Ranging with other technologies, such as artificial intelligence (AI) and machine learning, holds tremendous potential. Additionally, AI algorithms can analyze radar data in real-time, identifying patterns, predicting object behavior, and enabling proactive decision-making.

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Chakrasthitha is a B.E (Medical Electronics) and has work experience in MatLab and Lab View Software as Design Engineer at BCS innovations and Manipal hospital as Biomedical Engineer. She is an author, editor and partner at Electricalfundablog.


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