Introduction to Radio Engineering

Nathan Blaunstein, Christos Christodoulou, Mikhail Sergeev

• Publisher: CRC Press
• Year: 2016
• eBook ISBN: 9781315350080
• Edition: 1
• Topic: Technology & Engineering
• Subtopic: Information Technology
• Index: Technology & Engineering

The book introduces the basic foundations of high mathematics and vector algebra. Then, it explains the basic aspects of classical electrodynamics and electromagnetism. Based on such knowledge readers investigate various radio propagation problems related to guiding structures connecting electronic devices with antenna terminals placed at the different radar systems. It explains the role of antennas in process of transmission of radio signals between the terminals. Finally, it shows the relation between the main operational charactistics of each kind of radar and the corresponding knowledge obtained from the previous chapters.

V RADAR FUNDAMENTALS

Chapter 11

Radars

First of all, we will introduce the reader to the main definitions, which are important for a detailed explanation of the subject.

11.1Basic Definitions and Characteristics of Radar

Radar is a device that transmits and receives electromagnetic signals for a variety of applications, including detection, tracking, classification, identification, surveillance, imaging, and guiding targets. The acronym “RADAR” stands for “Radio Detection And Ranging” system, which includes the most prevalent applications of microwave and millimeter-wave technology [1–17].

Target is the object of interest, which is embedded in noise and clutter together with interfering signals.

Noise is a floor signal, which limits the smallest signal that can be measured by the receiver.

Clutter is a radar (or background) echo or group of echoes from ground, sea, rain, birds, and so on that is operationally unwanted in the situation being considered for detecting, tracking, and identification of the desired target.

However, we note that these definitions are relative and depend on the situation of application. What is clutter for some purposes may be a target for others. For example, an echo from rain is clutter for airport surveillance radar, but it is the target for weather radar.

Surveillance is the systematic observation of a region (aerospace, surface, or subsurface areas) by different numbers of various sensors for detecting, tracking, classifying, and identifying targets and activities of interest [2,4,6–13]: air-to-air (A-A), air-to-ground (A-G), air-to-surface (A-S), surface to air (S-A), surface-to-surface (S-S), and so on.

Frequency (or wavelength) is a basic radar parameter that determines not only the design and construction of radar, but also its application and performance.

Table 11.1 presents most specific radar frequency bands. Ground-based penetrating radars are usually in the L, S, and C frequency band regions, whereas airborne radars are usually in the X-band region. Millimeter-wave (MMW) radars operate at frequencies exceeding 30 GHz; V-band (40–75 GHz), and W-band (75–110 GHz) are also used in MMW radars [11].

Table 11.1Radar Frequency Bands
Band	Frequency Range (GHz)	Wavelength (cm)
VHF	0.03–0.3	1000–100
UHF	0.3–1.0	100–30
L	1.0–2.0	30–15
S	2.0–4.0	15–7.5
C	4.0–8.0	7.5–3.75
X	8.0–12.5	3.75–2.40
Ku	12.5–18.0	2.40–1.67
K	18.0–26.5	1.67–1.13
Ka	26.5–40.0	1.13–0.75
MMW	40.0–100	0.75–0.3

Resolution is the radar’s ability to distinguish two targets in close proximity to each other in three-dimensional (3-D) space: (a) range (in the space domain); (b) velocity (in the Doppler domain).

Accuracy is the ability of the radar to measure the true value (true range, velocity, direction, etc.).

In its basic operation, a radar transmitter sends out a radio signal, continuous or pulsed, which is partly reflected by a desired target and then detected by a sensitive radar receiver. If the radar uses a narrow-beam antenna, the target’s direction can be accurately given with respect to th...

Table of contents

• Cover
• Half title
• Title Page
• Copyright Page
• Contents
• Preface
• Acknowledgments
• Authors
• Symbols and Abbreviations
• SECTION I MATHEMATICAL FOUNDATIONS FOR RADIO ENGINEERING
• SECTION II NTRODUCTION TO CLASSICAL ELECTRODYNAMICS
• SECTION III GUIDING STRUCTURES AND GUIDING WAVES
• SECTION IV ANTENA FUNDAMENTALS
• SECTION V RADAR FUNDAMENTALS
• Index