天线理论分析与设计第三版

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巴拉尼斯天线理论英文原版巴拉尼斯天线理论英文原版是 Constantine A. Balanis 教授编写的天线理论教材第三版，该书是天线理论研究者的必读书籍。下面是从这本书中提取的重要知识点。一、天线理论基础 * 电romagnetic波的基本概念：电romagnetic波是由电场和磁场组成的，电场和磁场之间存在着紧密的联系。 * 天线的定义：天线是一种将电romagnetic波转换为电信号或将电信号转换为电romagnetic波的设备。 * 天线的分类：天线可以分为两类：天线阵列和天线网络。二、天线理论分析 * 电romagnetic场的分析：电romagnetic场可以用 Maxwell 方程式来描述， Maxwell 方程式是电romagnetic理论的基础。 * 天线的 radiation 模式：天线的 radiation 模式可以用 radiation 模式理论来描述，该理论可以用来分析天线的 radiation 性能。 * 天线的 impedance 模式：天线的 impedance 模式可以用 impedance 模式理论来描述，该理论可以用来分析天线的 impedance 性能。三、天线设计 * 天线设计的基本原则：天线设计需要考虑到电romagnetic理论、材料科学和机械工程等多个方面。 * 天线设计的方法：天线设计可以使用 Computer-Aided Design (CAD) 软件和Finite-Difference Time-Domain (FDTD) 模拟方法等。 * 天线设计的优化：天线设计需要进行优化，以提高天线的性能和效率。四、天线应用 * 天线在通信系统中的应用：天线在通信系统中扮演着关键角色，例如在 wireless 通信系统和 satellite 通信系统中。 * 天线在雷达系统中的应用：天线在雷达系统中用于检测和跟踪目标。 * 天线在医疗应用中的应用：天线在医疗应用中用于 medical imaging 和治疗等。五、天线理论发展趋势 * 天线理论的发展趋势：天线理论正在不断发展，例如多天线技术、智能天线技术等。 * 天线理论在未来应用中的角色：天线理论在未来应用中将扮演着越来越重要的角色，例如在 fifth-generation (5G) 通信系统和 Internet of Things (IoT) 等。巴拉尼斯天线理论英文原版是天线理论研究者的必读书籍，该书涵盖了天线理论的基础知识、分析方法、设计方法和应用领域等方面的内容。

2 ANTENNAS

E-field

Radiated free-space waveAntennaTransmission lineSource

Figure 1.1 Antenna as a transition device.

power is delivered to the antenna under conjugate matching. This is discussed in

Section 2.13.

The reﬂected waves from the interface create, along with the traveling waves

from the source toward the antenna, constructive and destructive interference patterns,

referred to as standing waves, inside the transmission line which represent pockets of

energy concentrations and storage, typical of resonant devices. A typical standing wave

pattern is shown dashed in Figure 1.2, while another is exhibited in Figure 1.15. If the

antenna system is not properly designed, the transmission line could act to a large

degree as an energy storage element instead of as a wave guiding and energy trans-

porting device. If the maximum ﬁeld intensities of the standing wave are sufﬁciently

large, they can cause arching inside the transmission lines.

The losses due to the line, antenna, and the standing waves are undesirable. The

losses due to the line can be minimized by selecting low-loss lines while those of

INTRODUCTION 3

Standing wave

= (R

+ R

) + jX

Source

Antennna

Transmission line

Figure 1.2 Transmission-line Thevenin equivalent of antenna in transmitting mode.

the antenna can be decreased by reducing the loss resistance represented by R

Figure 1.2. The standing waves can be reduced, and the energy storage capacity of the

line minimized, by matching the impedance of the antenna (load) to the characteris-

tic impedance of the line. This is the same as matching loads to transmission lines,

where the load here is the antenna, and is discussed more in detail in Section 9.7.

An equivalent similar to that of Figure 1.2 is used to represent the antenna system in

the receiving mode where the source is replaced by a receiver. All other parts of the

transmission-line equivalent remain the same. The radiation resistance R

is used to

represent in the receiving mode the transfer of energy from the free-space wave to the

antenna. This is discussed in Section 2.13 and represented by the Thevenin and Norton

circuit equivalents of Figure 2.27.

In addition to receiving or transmitting energy, an antenna in an advanced wireless

system is usually required to optimize or accentuate the radiation energy in some

directions and suppress it in others. Thus the antenna must also serve as a directional

device in addition to a probing device. It must then take various forms to meet the

particular need at hand, and it may be a piece of conducting wire, an aperture, a patch,

an assembly of elements (array), a reﬂector, a lens, and so forth.

For wireless communication systems, the antenna is one of the most critical com-

ponents. A good design of the antenna can relax system requirements and improve

overall system performance. A typical example is TV for which the overall broad-

cast reception can be improved by utilizing a high-performance antenna. The antenna

serves to a communication system the same purpose that eyes and eyeglasses serve to

a human.

The ﬁeld of antennas is vigorous and dynamic, and over the last 60 years antenna

technology has been an indispensable partner of the communications revolution. Many

major advances that occurred during this period are in common use today; however,

many more issues and challenges are facing us today, especially since the demands

for system performances are even greater. Many of the major advances in antenna

technology that have been completed in the 1970s through the early 1990s, those that

were under way in the early 1990s, and signals of future discoveries and breakthroughs

were captured in a special issue of the Proceedings of the IEEE (Vol. 80, No. 1, January

1992) devoted to Antennas. The introductory paper of this special issue [1] provides

a carefully structured, elegant discussion of the fundamental principles of radiating

elements and has been written as an introduction for the nonspecialist and a review

for the expert.

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