Radar Systems Tutorial

Radar Systems Tutorial

RADAR stands for Radio Detection and Ranging. Radar System is an advanced electronic system using modern radio wave technology to determine the directions, measure the distances and velocities of objects with respect to their locations.

Radar systems are known for their accuracy in measurement. Today, these systems are playing an important role in various fields, from air traffic control to ships navigation, space exploration, and weather forecasting. A radar system works by transmitting electromagnetic waves and analyzing their reflections.

Historically, radar systems were developed for military applications during World War II. Modern radar systems are being used along with advanced technologies like digital signal processing, artificial intelligence, and machine learning to provide more precise and reliable operations.

This tutorial on Radar Systems is meant to provide the readers to know and understand the working of various Radars that are used for detecting either stationary or non-stationary objects. It also provides the details of various Antennas that are used in Radar communication. So, this tutorial gives the overview of Radar communication.

What is RADAR?

RADAR or Radio Detection and Ranging is an electronic system that makes the use of radio frequency waves for detecting and measuring the distance, direction, and velocity of objects.

A radar system transmits radio waves to the object and analyzes their reflections to perform these measurements. Hence, a radar system can detect the objects which are impossible to see with human sight. The most important feature of radar systems is that they also work in adverse weather conditions like darkness and fog.

Parts of a RADAR System

The block diagram of a typical radar system is shown in the following figure −

Components of Radar System

The main components of the radar system and their functions are described here −

1. Antenna Unit

It comprises of two main components namely, a radar antenna and an electric motor. The antenna radiates radio wave to the objects and receives the reflected waves from the objects. The electric motor rotates the antenna in a specific direction to ensure reliable tracking of objects.

2. Transceiver Unit

It acts as the heart of radar system and consists of a transmitter and a receiver. The transmitter is responsible for generating and transmitting radio or micro waves, while the receiver is provided to receive the reflected signals from the objects. This transmission and reception of radio waves take place through the antenna unit.

3. Duplexer

It is a device that provides bidirectional flow of signals through a single path. In radar systems, it is used for isolating transmitter and receiver while allowing them to share the same antenna.

4. Signal Processing Unit

This is also known as radar processor. This unit is responsible for analyzing the signals received by the receiver unit to determine the distance, velocity, and direction of the objects

5. Display

This component of the radar system provides a visual representation of results produced by the processor unit. It shows information like distance, velocity, movement patterns, current position, etc. of the objects.

Working Principle of Radar System

The working of a radar system is based on the transmission and reflection of radio frequency electromagnetic waves. The step-by-step operation of a typical radar system is explained below −

Step 1 − Radar system generates a pulse of radio waves using a transmitter and sends it towards an object through the antenna unit.

Step 2 − The radio waves propagate to the object.

Step 3 − After hitting the object, some portion of the radio waves reflects back by the object's surface.

Step 4 − The reflected radio waves are then received by the antenna.

Step 5 − The received radio waves are processed and analyzed by the signal processor to determine the distance, direction, and velocity of the object. These observations are then shown on a display screen.

Types of RADAR Systems

Depending on the scanning pattern, configuration, and applications, the radar systems can be classified into various types. Some of the most common types of radar systems are listed and explained here −

• Monostatic Radar System − It is a type of radar system in which the transmitter and receiver combinedly use the same antenna for transmission and reception of electromagnetic signals. These radar systems are mainly used in applications like air traffic control, monitoring weather conditions, surveillance, etc.
• Bistatic Radar System − In a bistatic radar system, the transmitter and receiver are located at two different locations. The distance between transmitter and receiver is kept equivalent to expected distance from the targeted object. This radar system is mainly used in long-range, military, or weather-related applications.
• Monopulse Radar System − A monopulse radar system is an advanced radar system mainly used for measuring the angle of a target and tracking applications. This radar system can determine the distance and angle at the same time by using a single pulse.
• Doppler Radar System − The doppler radar system is a radar system that uses the doppler effect to calculate the velocity of a target object. This radar system works by sending a microwave signal towards the object whose velocity to be measured, and then it analyzes how the motion of reflected signal has changed. The doppler radar system finds its usage in applications like radiology, healthcare, military, aviation, etc.
• Passive Radar System − A radar system that uses signals produced by sources in the surrounding environment like communication or broadcasting signals for measuring and tracking purposes is called a passive radar system. In this radar system, no dedicated transmitter is used.
• Pulse Radar System − A pulse radar system is one which works by transmitting a powerful pulse of high-frequency towards an object and waits until the reflected signal is received from the object before sending another pulse. The detection of object using pulse radar is based on the concept of doppler shift.
• Continuous Wave Radar System − The CW radar system works by sending and receiving high-frequency radio waves continuously. The working of continuous wave radar is based on the doppler frequency shift produced by moving objects.

Advantages and Limitations of RADAR Systems

The following table highlights the key benefits and limitations of radar systems −

Applications of RADAR Systems

Today, Radar Systems find their applications across a wide range of fields. Some of the common applications of radar systems are given below −

• Radar systems are widely being used in aviation industry for managing the air traffic and ensuring safe navigation of aircrafts.
• Radar systems are also a valuable tool in defense operations and are used for detecting and tracking enemy ships, aircrafts, and missiles.
• Radar systems are also employed for ship navigation and avoiding collusions.
• Radar systems are also used in autonomous vehicles for applications like ADAS (Advanced Driver Assistance Systems) or ACC (Adaptive Cruise Control).
• In weather forecasting, radar systems are used to determine the weather patterns and predict storms.

What You Will Learn in This Radar Systems Tutorial?

This tutorial is designed to explain basics to advanced concepts related to radar systems. The topics covered in this tutorial are listed and described in the following list −

• Radar Systems Overview − This chapter provides an overview of radar systems and definitions of some important terms related to radar.
• Radar System Range Equation − In this chapter, you will learn to derive radar range equation and its application in real-world situations.
• Radar Systems Performance Factors − This chapter describes various factors affecting the performance of radar systems.
• Types of Radars − This chapter discusses about different types of radar systems.
• Pulse Radar − This section is meant for explaining the block diagram and working of the pulse radar.
• Doppler Effect − In this chapter, you will learn about the Doppler Effect in radar systems.
• CW Radar − This section explains the block diagram and working of the continuous wave radar.
• FMCW Radar − This chapter explains the block diagram and working of FMCW radar.
• MTI Radar − In this chapter, you will explore about types, block diagram, and working of moving target indicator (MTI) radar.
• Delay Line Cancellers − This chapter explains different types of delay line cancellers used in radar systems.
• Tracking Radar − This chapter explains the functioning of different types of tracking radar.
• Antenna Parameters − This section defines some important parameters of a radar antenna.
• Radar Antennas − This chapter is meant for explaining the construction and working of different types of radar antennas.
• Matched Filter Receiver − This chapter describes the working and analysis of matched filter receiver used in radar systems.
• Radar Displays − In this section, you will learn about different types of displays used in radar systems.
• Duplexers − This chapter explains the construction and working of different types of duplexers.
• Phase Array Antennas − In this chapter, you will learn about basics and radiation pattern of phased array antennas.

Who Should Learn RADAR Systems?

This tutorial is meant for all the readers who are aspiring to learn the concepts of Radar Systems. In some universities, this subject is also called as "Radar Communication", thus students can also use this tutorial as a useful resource on radar systems.

This tutorial on Radar Systems will be equally useful for professionals working in the industries that use radar communication.

Prerequisites to Learn RADAR Systems

This tutorial is mainly designed for beginner students in radar technology. However, the fundamental concepts covered in Analog Communication and Antenna Theory tutorials will be very useful for understanding the concepts discussed in this tutorial.

Additionally, a basic understanding of concepts of electromagnetic waves, signal processing, and basic physics and mathematics will make the learning process smoother.

FAQs on RADAR Systems

This section is provided to briefly answer some of the most Frequently Asked Questions (FAQs) related to Radar Systems.

1. What is the range of a typical radar system?

The range or distance over which a radar system can be used is not fixed, but it depends on several factors like type of radar, environmental condition, antenna size, losses in system, power of transmitter, etc. However, it can vary from a few meters to several hundred kilometers.

2. What are the applications of Doppler radar?

Doppler radar is used for measuring the velocity of moving objects, and it finds applications in the following −

• Speed cameras
• Radar guns
• Warfare
• Weather forecasting systems, etc.

3. Can radar penetrate walls?

Yes, radar at low radio frequencies can penetrate walls of buildings. It can also penetrate through materials like poured concrete, concrete block, brick, wood, stucco glass, adobe, dirt, etc.

4. What is the difference between Sonar and Radar?

The most significant difference between sonar and radar is in their use of electromagnetic radiation. Radar systems use radio frequency waves, while Sonar systems use ultrasonic sound waves. However, both technologies are used for detecting objects and their locations.

Another key difference between radar and sonar is that radar is mainly used in air or free space, while sonar is manly used to detect underwater objects.

5. What is the full form of Radar?

The full form of Radar is "Radio Detection and Ranging".