天线的性能毕业外文翻译.docx

目录 TOC \o 1-5 \h \z PROPERTIES OF ANTENNAS 2 HYPERLINK \l bookmark4 \o Current Document 2. 1 ANTENNA RADIATION 3 HYPERLINK \l bookmark6 \o Current Document 2.2 GAIN 5 HYPERLINK \l bookmark12 \o Current Document 2. 3 EFFECTIVE AREA 8 HYPERLINK \l bookmark14 \o Current Document 2. 4 PATH LOSS 8 HYPERLINK \l bookmark22 \o Current Document 2. 5 RADAR RANGE EQUATION AND CROSS SECTION 10 HYPERLINK \l bookmark24 \o Current Document 2. 6 WHY USE AN ANTENNA? 12 HYPERLINK \l bookmark28 \o Current Document 天线的功能 12 HYPERLINK \l bookmark30 \o Current Document 2. 1天线辐射 13 HYPERLINK \l bookmark34 \o Current Document 2.2天线增益 15 HYPERLINK \l bookmark38 \o Current Document 2. 3天线有效面积 17 HYPERLINK \l bookmark40 \o Current Document 2. 4路径损耗 18 HYPERLINK \l bookmark46 \o Current Document 2. 5雷达距离方程和截面 19 HYPERLINK \l bookmark52 \o Current Document 2. 6为什么使用一个天线？ 21 英文原文: PROPERTIES OF ANTENNAS One approach to an antenna book starts with a discussion of how antennas radiate. Beginning with MaxwelPs equations, we derive electromagnetic waves. After that lengthy discussion, which contains a lot of mathematics, we discuss how these waves excite currents on conductors? The second half of the story is that currents radiate and produce electromagnetic waves. You may already have studied that subject, or if you wish to further your background, consult books on electromagnetics.The study of electromagnetics gives insight into the mathematics describing antenna radiation and provides the rigor to prevent mistakes. We skip the discussion of those equations and move directly to practical aspects. It is important to realize that antennas radiate from currents. Design consists of controlling currents to produce the desired radiation distribution, called its pattern .In many situations the problem is how to prevent radiation from currents, such as in circuits. Whenever a current becomes separated in distance from its return current, it radiates. Simply stated, we design to keep the two