本书供高等院校信息科学、通信工程、电子技术、计算机应用等专业的本科生和研究生学习专业英语之用。选材兼顾经典题材和新兴技术,在编写中摈弃过分依赖语法、死记硬背的陈旧教学方法,注重培养学生以较高准确性和足够的速度阅读专业资料和文献的能力,兼顾一定的专业英语表达能力,从阅读、翻译、写作等角度提高学生对专业英语的应用能力。
全书共17单元,各单元包括课文、词汇、难点注释、课外阅读资料、习题。书后附有关于科技英语阅读、写作、克服中式英语等问题的指南和讨论。

EM Fields, Antenna and
Microwaves
As a result of the growth of microwave technology and its applications, and especially with the rapid development of wireless communications in recent years, professionals who are working in the areas of microwaves as well as communication engineering are all faced with the need to understand the theoretical and experimental aspects of microwave devices and circuits, and the design of antennas.
Text
Part I: Electromagnetic Field
The electromagnetic field is a physical field produced by electrically charged objects. It affects the behavior of charged objects in the vicinity of the field. The electromagnetic field extends indefinitely throughout space and describes the electromagnetic interaction. It is one of the four fundamental forces in the nature (the others are gravitation, the weak interaction, and the strong interaction).
The field can be viewed as the combination of an electric field and a magnetic field. The electric field is produced by stationary charges, and the magnetic field by moving charges (currents); these two are often described as the sources of the field. The way in which charges and currents interact with the electromagnetic field is described by Maxwell’s equations and the Lorentz force law.
From a classical point of view, the electromagnetic field can be regarded as a smooth, continuous field, propagated in a wavelike manner, whereas from a quantum mechanical point of view, the field can be viewed as being composed of photons.
Structure of the electromagnetic field
The electromagnetic field may be viewed in two distinct ways.
Continuous structure: Classically, electric and magnetic fields are thought of as being produced by smooth motions of charged objects. For example, oscillating charges produce electric and magnetic fields that may be viewed in a “smooth”, continuous, wavelike manner. In this case, energy is viewed as being transferred continuously through the electromagnetic field between any two locations. For instance, the metal atoms in a radio transmitter appear to transfer energy continuously. This view is useful to a certain extent (radiation of low frequency), but problems are found at high frequencies (see ultraviolet catastrophe). This problem leads to another view.
Discrete structure: The electromagnetic field may be thought of in a more “coarse” way. Experiments reveal that electromagnetic energy transfer is better described as being carried away in photons with a fixed frequency. Planck’s relation links the energy E of a photon to its frequency ? through the equation:
E = h ?
where h is Planck’s constant, named in honor of Max Planck, and ? is the frequency of the photon. For example, in the photoelectric effect—the emission of electrons from metallic surfaces by electromagnetic radiation—it is found that increasing the intensity of the incident radiation has no effect, and that only the frequency of the radiation is relevant in ejecting electrons.1
This quantum picture of the electromagnetic field has proved very successful, giving rise to quantum electrodynamics, a quantum field theory describing the interaction of electromagnetic radiation with charged matter.
Dynamics of the electromagnetic field
In the past, electrically charged objects were thought to produce two types of field associated with their charge property. An electric field is produced when the charge is stationary with respect to an observer measuring the properties of the charge and a magnetic field (as well as an electric field) is produced when the charge moves (creating an electric current) with respect to this observer. Over time, it was realized that the electric and magnetic fields are better thought of as two parts of a greater whole—the electromagnetic field.2
Once this electromagnetic field has been produced from a given charge distribution, other charged objects in this field will experience a force (in a similar way that planets experience a force in the gravitational field of the Sun). If these other charges and currents are comparable in size to the sources producing the above electromagnetic field, then a new net electromagnetic field will be produced.3 Thus, the electromagnetic field may be viewed as a dynamic entity that causes other charges and currents to move, and which is also affected by them. These interactions are described by Maxwell’s equations and the Lorentz force law.
Part Ⅱ: Microstrip Antenna
In telecommunication, there are several types of microstrip antennas (also known as printed antennas) the most common of which is the microstrip patch antenna or patch antenna. A patch antenna is a narrowband, wide-beam antenna fabricated by etching the antenna element pattern in metal trace bonded to an insulating dielectric substrate with a continuous metal layer bonded to the opposite side of the substrate which forms a ground plane.1 Common microstrip antenna radiator shapes are square, rectangular, circular and elliptical, but any continuous shape is possible. Some patch antennas eschew a dielectric substrate and suspend a metal patch in air above a ground plane using dielectric spacers; the resulting structure is less robust but provides better bandwidth. Because such antennas have a very low profile, are mechanically rugged and can be conformable, they are often mounted on the exterior of aircraft and spacecraft, or are incorporated into mobile radio communications devices.2
Microstrip antennas are also relatively inexpensive to manufacture and design because of the simple 2-dimensional physical geometry. They are usually employed at UHF and higher frequencies because the size of the antenna is directly tied to the wavelength at the resonant frequency. A single patch antenna provides a maximum directive gain of around 6~9 dBi. It is relatively easy to print an array of patches on a single (large) substrate using lithographic techniques. Patch arrays can provide much higher gains than a single patch at little additional cost; matching and phase adjustment can be performed with printed microstrip feed structures, again in the same operations that form the radiating patches. The ability to create high gain arrays in a low-profile antenna is one reason that patch arrays are common on airplanes and in other military applications.

Unit 1 Electronics: Analog and Digital 1
Text 1
Part I: Ideal Operational Amplifiers and Practical Limitations 1
Part II: Data Registers and Counters 3
Part III: Nature of Phase Lock 6
New Words 8
Notes on the Text 9
Technical Tips 12
Supplementary Readings: Bridging the Gap between the
Analog and Digital Worlds 13
Exercises 17
Unit 2 Integrated Circuits 21
Text 21
Part I: The Integrated Circuit 21
Part II: Application Specific Integrated Circuit 24
New Words 27
Notes on the Text 28
Technical Tips 31
Supplementary Readings 31
Exercises 34
Unit 3 EM Fields, Antenna and Microwaves 37
Text 37
Part I: Electromagnetic Field 37
Part Ⅱ: Microstrip Antenna 38
Part Ⅲ: Microwaves 40
New Words 43
Notes on the Text 44
Technical Tips 46
Supplementary Readings: What Are Microwaves? 46
Exercises 50
Unit 4 Communication and Information Theory 53
Text 53
Part I: Telecommunication 53
Part Ⅱ: Data Transmission 55
Part Ⅲ: Information Theory 56
New Words 59
Notes on the Text 60
Technical Tips 63
Supplementary Readings 63
Exercises 66
Unit 5 Multiple Access Techniques 70
Text 70
Part I: Multiple Access Techniques: FDMA, TDMA and CDMA 70
Part Ⅱ: Orthogonal Frequency Division Multiplexing 76
New Words 79
Notes on the Text 80
Technical Tips 82
Supplementary Readings: Wavelength-Division Multiplexing 82
Exercises 85
Unit 6 Mobile Communications 88
Text 88
Part I: Mobile Communications 88
Part Ⅱ: Fourth Generation Wireless Networks 91
New Words 94
Notes on the Text 95
Technical Tips 97
Supplementary Readings: The Road to 5G 98
Exercises 102
Unit 7 Optical Communications 104
Text 104
Part I: Electromagnetic Spectrum 104
Part Ⅱ: Optical Fiber 107
New Words 111
Notes on the Text 112
Technical Tips 115
Supplementary Readings: Optical Systems 116
Exercises 119
Unit 8 Digital Signals and Signal Processing 122
Text 122
Part I: Digital Signal Processing 122
Part Ⅱ: General Concepts of Digital Signal Processing 125
New Words 130
Notes on the Text 132
Technical Tips 134
Supplementary Readings: Designing Digital Filters 135
Exercises 141
Unit 9 Digital Audio Compression 145
Text 145
Part I: MPEG Audio Layer 3 145
Part Ⅱ: Digital Audio Compression Standard AC3 147
New Words 151
Notes on the Text 152
Technical Tips 154
Supplementary Readings: Audio Compression Algorithm Overview 155
Exercises 159
Unit 10 Digital Image Processing 162
Text 162
Part I: Two-Dimensional Digital Images 162
Part Ⅱ: Digital Images ? Definition and Applications 164
Part Ⅲ: Introduction to Image Processing 167
New Words 172
Notes on the Text 174
Technical Tips 180
Supplementary Readings 180
Exercises 186
Unit 11 Biometrics Technology 188
Text 188
Part I: Fingerprint Identification 188
Part Ⅱ: Introduction to Speaker Identification 190
New Words 195
Notes on the Text 196
Technical Tips 199
Supplementary Readings: Biometrics Overview 200
Exercises 204
Unit 12 Information Security 207
Text 207
Part I: Information Security — Introduction and a Brief History 207
Part Ⅱ: Basic Principles of Information Security 208
Part Ⅲ: Intrusion Detection System 210
New Words 212
Notes on the Text 214
Technical Tips 217
Supplementary Readings: Hidden Communication 218
Exercises 223
Unit 13 Telemedicine and Biomedical Signal Processing 226
Text 226
Part I: Telemedicine 226
Part Ⅱ: Computerized Tomographic Imaging 228
New Words 230
Notes on the Text 231
Technical Tips 234
Supplementary Readings: Biomedical Signal Processing 234
Exercises 237
Unit 14 Computers and Networks 240
Text 240
Part I: Evolution of Computers 240
Part Ⅱ: Local Area Networks 244
New Words 249
Notes on the Text 250
Technical Tips 253
Supplementary Readings 254
Exercises 258
Unit 15 Artificial Intelligence 262
Text 262
Part I: What Is Artificial Intelligence 262
Part Ⅱ: Approaches of AI 264
New Words 268
Notes on the Text 269
Technical Tips 271
Supplementary Readings: AlphaGo 272
Exercises 275
Unit 16 Big Data and Cloud Computing 278
Text 278
Part I: Big Data 278
Part Ⅱ: Cloud Computing 282
New Words 286
Notes on the Text 287
Technical Tips 289
Supplementary Readings: Smart City 290
Exercises 294
Unit 17 Internet of Things (IoT) 296
Text 296
Part I: Internet of Things: Concept and Key Technologies 296
Part Ⅱ: IoT Applications 299
New Words 303
Notes on the Text 304
Technical Tips 306
Supplementary Readings: Wireless Sensor Network 307
Exercises 310
Appendices 312
I. How Should We Read English 312
Ⅱ. Writing Technical English 314
Ⅲ. Avoid Pidgin English 329
Ⅳ. Title of Scientific Papers 337
Ⅴ. How to Write Abstract 339
Bibliography 343