Thursday, June 11, 2009

A Nice Introduction to RADAR


Here is a rather amusing book review by Prachi Deshmukh, a bright young engineer who works with me.

It was written quite some time back and I like her rather droll friendly style and, hence, I have intentionally not edited the review too much, so that the writing retains its original refreshing youthful flavour. So here is the book review E & OE :-

Name of the book: Radar
Authors: P.S. Hall, T.K. Garland-Collins, R.S. Picton and R.G. Lee
Publication: Brassey’s , (UK), 1991
Pages: 170
ISBN: 0 – 08 – 037710 – 6

[Reviewed by Prachi A. Deshmukh]

It was a bright morning, and I was enjoying my first tea of the day. Usually, I do not take tea without having a glance on the newspaper. There were plenty of news showing the fall of the top Indian software companies, the falling share market and there were overflowing columns discussing about the global recession. I was getting somewhat bored by reading them, and suddenly a news attracted me, which was about the bravery of a pilot in USA who saved the life of nearly 160 passengers. The brave man did land the plane in a frozen river to rescue the passengers in the plane and saved it from crash, which could happen because of a bird approaching towards the plane. Hats off to the presence of mind of the pilot! At the same time, we should not forget to say thanks to the radar technology, which had helped the pilot to detect the presence of the approaching bird.

After reading this, I became curious about the RADAR technology. ‘RADAR’ is the abbreviation of ‘Radio Detection and Ranging’. I went to the library in search of the book which will make me familiar with this RADAR technology. There were number of books available there, out of which, I selected one book, which I think was best suitable for a reader who is interested in to know the basic operation of RADAR, but does not have detailed knowledge of electronics or RADAR system, but is interested to know about the modern warfare.

The book about which I am talking is ‘Radar’ by P.S. Hall et al, Brassey’s Publication, UK. ‘RADAR’ is the 9th volume of the series ‘Land Warfare: Brassey’s New Battlefield Weapons Systems and Technology Series’.

The content in the book is well arranged in 10 chapters, each having plenty of supporting diagrams, equations as well as photographs. The first chapter introduces us with radar. We enter in the world of radar with knowing the importance of radar, its history, i.e. origin of radar, motivation behind it, its first use in army etc. We also go through the technical history of radar. At the end of the first chapter, we become familiar with the types of radar such as primary and secondary radar, monostatic, bistatic and multistatic radar. The last figure of this chapter shows the electromagnetic spectrum and the radar bands in it.
The chapters 2 to 4 deal with the radar principles and technology. It is advised that the readers who wish to strengthen their fundamentals should study these chapters carefully. For those who are new to this field or want the comprehensive view, all the chapters are recommended. Those who understand the basics but wish to update themselves on the current state of battlefield radars chapter no. 5 to 9 are there.

Chapter 2 is about the ‘Principles of Radar Operation’. This chapter introduces us with the basic principles of radar operation such as basic action of the Pulse Radar Operation, Pulse Repetition Frequency, evaluation of the performance of radar , how to design the antenna, the maximum detection range and the radar equation etc. At the end of the chapter we gain the knowledge about the detection of radar signals, radar resolution, velocity resolution, radar accuracy and how to choose the frequency of radar.

Chapter 3 is an interesting one. Here we become familiar with the Doppler radar, Doppler processing in pulse radars, blind and ambiguous velocity. Besides these concepts, there are some other important radar techniques also, such as methods of target discrimination, Rain Clutter suppression by circular polarization, pulse compression, scanning and tracking radars, synthetic aperture radar. After going through this chapter, we find that we have acquired enough fundamentals to thoroughly understand the radar technology.

The fourth chapter is ‘radar technology’. Here we have to make use of the knowledge which we have gained in the previous chapters. At the beginning of this chapter we have a look on what are radar transmitters and receivers, what is magnetron, Klystron, Travelling wave tube, solid state transmitters etc. Without the knowledge of the components of radar, can we understand what the system actually is?

The common microwave transmission lines such as waveguide, co-axial, line, microstrip, triplate stripline are illustrated in brief. Antennas are the important sense organs for the radars. Here are the different types of antennas such as reflector antennas, adaptive antennas, multiple beam antennas as well as the phase arrays, frequency scanned arrays. Digital processing and displays are also explained in brief. If the displays could have been explained in detail, it would be better.

With chapter 5, we move towards the battlefield surveillance radar. First the authors introduce us with the requirement of the battlefield surveillance radar. Mainly there are two classes of battlefield surveillance radar i.e. Short range battlefield surveillance radar and airborne battlefield surveillance radar. In Short range battlefield (BSR) radar, there are different points which should be taken into consideration while studying BSR. The important points are frequency of operation and resolution. The block diagram is there to understand the working of the BSR. There are some examples of current BSR such as RASIT radar and MSTAR radar. The photographs give us the idea about the systems. The second important type is the airborne battlefield surveillance radar. Here we go through the Stand-Off Radar (SOR) which stand well back and use long range sensors. Again we gain knowledge about the principle of SOR, SOR resolution, target imaging and displays. At the end of the chapter there are two practical systems also.

Chapter 6 is about the weapon locating radars. The purpose of the weapon locating radar is to detect the launch of an enemy projectile or missile and to establish the segment of the trajectory of projectile. The general technical requirements, principle of back track location provide us with base to understand the fundamentals. Here are some practical systems, recently introduced systems, near future outlook and possible future systems.

Chapter 7 is about the Air Defence Radar. In this chapter the important types such as strategic radars, long range radars, medium range radars and short range radars and surveillance and tracking of each of the type are studied. All the four types are presented very nicely with enough diagrams and photographs.
In chapter 8, there is collection of some other types of battlefield radars. To mention few are: balloon tracking radar, free flight rocket correction radar, unmanned aircraft radar, remotely piloted vehicle tracking radar, tank Automatic defence radar , as well as radar anti–tank homing missiles and projectiles and passive radar homing missiles. At the end of this chapter, we acquire some command on the radar systems.

Chapter 9 is about the electronic warfare. Here the authors have introduced us with the Electronic Warfare (EW). This chapter gives a brief idea about the electronic warfare. Electronic Counter Measures (ECM), Electronic Support Measures (ESM) and Electronic Counter Countermeasures (ECCM), jamming are some of the important concepts of EW. Here we get a brief knowledge of the tactical aspects, antenna systems, and jammers. Comparisons between ESM and radar confrontation, tracking radar and threat borne jammer, tracker and repeater target borne jammer help to make our concepts clear.

Last but not the least, chapter 10, which is the conclusion of the entire exercise. This chapter tells us about the importance of radar in battlefield, as well as it shows us the future of this technology. It includes the comparison of radar and other surveillance and target acquisition methods, the importance of the EW and its impact on radar, the future technical trends, adaptive radar, Artificial intelligence, and future military trends. This chapter is the most important one as far as the warfare is concerned.

For the sake of convenience of the keen reader who wants to see the particular diagrams, there is a chapter wise list of illustration at the beginning of the book.
In simple words, ‘Radar’ is a book which gives us sufficient information of Radar systems and makes us familiar with the Electronic Warfare also. This is a good example of a technical book. This book can be used by the students for reference who are studying Radar for academic purpose, as well as this will prove simple and helpful for those readers who do not have detailed knowledge of electronics or radar system. But reader must be from technical background and should have at least the basic knowledge of physics and electronics.

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