论坛首发 Foundations of antenna theory and techniques

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Preface
This book is designed as a set of topics that interlock in order to give the reader a
reasonably paced introduction to the theory that underpins antenna design techniques.
The earliest recorded pioneer of studies related to the creation and detection of
electromagnetic radiation through free space was Heinrich Rudolf Hertz (1857–1894).
Hertz demonstrated by a series of experiments around 1886 that electromagnetic waves
transmitted through the air had wave-like characteristics. By good fortune, the spark
gap means by which he created his electromagnetic energy generated centimetre wavelengths.
This involved creating a discharge of a Leyden jar (a capacitor) through one
coil while causing a spark to pass across a short air gap between the ends of the other
coil. Oliver Heaviside had pointed out in 1877 that such a discharge of a capacitor
in association with an inductor, the coil, would lead to oscillatory current. In effect,
Hertz created a broadband signal generator producing energy over a very wide range
of frequencies. Working at centimetre wavelengths meant that he could conveniently
reflect these waves by dielectric prisms and metal parabolic mirrors in much the same
way as light can be manipulated.
Hertz went on to show, using the principle of resonance, that with identical transmit
and receive circuits he could considerably increase the free-space transmission distance
between transmitter and receiver. In addition, he realised that the relationship
between electromagnetic wave propagation amplitude and distance obeyed the inverse
distance relationship. It is this property that makes wireless communication attractive
as a virtual wire communication means.
Among Hertz’s many key discoveries was the linear oscillator, comprising two metal
rods terminating in metal spheres. In fact, he had created a dipole antenna similar in
many respects to that much used in today’s communication systems. Using this dipole,
he showed that the electromagnetic waves he was producing had their electric field
component parallel to his rod antennas, i.e. they were linearly polarised. This principle
is used today to reduce interference between radio communication systems that
x Preface
share the same frequency response. Hertz’s seminal work ultimately led to the creation
of wireless communication across all the frequency ranges in use today.
The work of Hertz went a long way towards validating the set of mathematical relationships
postulated by James Clerk Maxwell (1831–1879). Maxwell’s equations give
the coherent framework within which it is possible to establish the relationships between
electricity, magnetism and electromagnetic wave propagation. Maxwell proved that
radio waves were an electromagnetic phenomenon and that their maximum speed of
propagation in a vacuum was the same as that of light, 3 × 108 m/s. His work showed
theoretically that, like light, electromagnetic waves could be focused using a parabolic
reflector. Maxwell’s equations are the starting point for RF and microwave designers
in their attempts to quantify and control electromagnetic wave phenomena in order to
produce useful engineering artefacts such as antennas.
Samuel Morse had invented the printing telegraph in 1835, while Alexander Graham
Bell had patented his telephone transmitter and receiver in 1876 and distant communication
over wires was established. The theoretical work of Maxwell, underpinned
by the supporting experimental evidence provided by Hertz, had by the 1890s led
to the idea that Hertzian waves as they were by that time known might be used as
an alternative to wire in order to transmit telegraphic or telephone signals over large
distances. The major thrust to providing realisation of these assertions came about as
a consequence of the work of Guglielmo Marconi (1874–1937), who from 1894 onwards
began to demonstrate wireless communication over useful distances.
A key breakthrough came when Marconi used transmit and receive antennas, which
were elevated above the ground. This dramatically improved free-space operating distance
from a few hundred metres to several kilometres. Encouraged by these results
and realising that one of the most commercially attractive uses for wireless communications
at that time was in facilitating ships in distress to summon assistance, Marconi
was granted the world’s first patent for a wireless telegraph in 1897.
Marconi then formed ‘The Wireless Telegraph and Signal Company Ltd’ later
to become ‘The Marconi Company’. A further significant technical breakthrough
for Marconi came in 1900, when he obtained a patent for a resonant tuner with a
variable capacitor, which could bring the transmitter and receiver into resonance. An
extension to this work meant that multiple antennas could be connected to a single
transmitter and receiver. With these improvements, Marconi’s company had a number
of commercial successes with shipboard coastal radio. His major success came in
December 1901, when he managed to receive a signal in Newfoundland that had
been sent from Cornwall in England. With this, the monopoly control by the British
Post Office of transatlantic submarine cable telephony was broken. In the period
1902 to the 1920s, many key developments related to long-wave wireless telephony
occurred; for example, valves were invented, which improved transmitter power and
receiver sensitivity. Short-wave transatlantic radio communications were pioneered
in the 1930s at AT&T, Western Electric and Bell Laboratories in the United States.
Engineers such as H.T. Friis and E. Bruce developed theories and antenna types that
are still widely used today.
The seminal work of these and other pioneers is constantly evolving, through
developments in radar in the 1950s to satellite communications in the 1960s and 1970s
and with the aid of miniaturisation in electronics to modern developments in adaptive
Preface xi
antennas for base station and multiband antennas for personal mobile communication
wireless handsets that are currently taking place.
The motivation for this book is the recent huge expansion in mobile telecommunications,
with the resultant scarcity of qualified RF specialists. One of the key areas of these
systems and perhaps the least understood is the point of entry or exit of a wireless
signal to and from the system, i.e. the antenna. Engineers with a working knowledge of
the basic fundamentals of these structures are increasingly in demand. Their scarcity
is compounded by the fact that many university undergraduate programmes have dropped
electromagnetic field courses in favour of more digital signal-processing type of activities.
Consequently, this book is intended to act as an interpretational guide to the many
volumes of excellent (but for the beginner sometimes hard to digest) material that exist
in classical textbooks on the subject of electromagnetic waves. Thus it is hoped that
this book will facilitate the basis for a study of the concepts that underpin antenna
theory and techniques.
The structure of the material is broadly as follows:
l basic concept of radiation and the elementary building block for linear antenna
modelling;
l plane wave propagation and power flow;
l basic antenna definitions and the concept of the linear dipole antenna;
l single and multiple dipole antenna radiation pattern formation;
l antenna systems and related characterisation methods;
l basic antenna-matching techniques;
l some popular antenna types.
The text is not meant to be a replacement for the many excellent textbooks on antenna
theory that currently exist. It is meant to act as a detailed first reference or as the core
of a training tool for those undergraduates, postgraduates or engineers wishing to receive
the fundamental theoretical underpinning required for a fruitful appreciation of this
rewarding subject.
V.F. Fusco
November 2004

veoncxmjler

非常感谢。。

veoncxmjler

非常感谢。。

huweiwell

非常感谢。。。。。。

wfyhb36

好多把啊，，

zin

多謝分享喔!應該不錯

asdzy2

楼主 请问有没有和这本书内容近似的中文书啊 最近在学这门课就用的这本书 英语看起来很吃力！

muxl1

看看了