电子信息工程专业英语翻译清华出版社English for IT and EE-03.ppt

* 15 Many semiconductor processing techniques use microwaves to generate plasma for such purposes as reactive ion etching and plasma-enhanced chemical vapor deposition (PECVD). 许多半导体处理工艺用微波来产生等离子体，用于反应离子蚀刻和等离子体增强化学汽相沉积。 * 16 Microwaves can be used to transmit power over long distances, and post-World War II research was done to examine possibilities. NASA worked in the 1970s and early 1980s to research the possibilities of using Solar Power Satellite (SPS) systems with large solar arrays that would beam power down to the Earth’s surface via microwaves.5 美国航空航天局在20世纪70~80年代初研究利用太阳能卫星系统的可能性，这种系统装有大型太阳能阵列，通过微波向地球表面发送能量。 * 17, 18 A maser is a device similar to a laser, except that it works at microwave frequencies. Most radio astronomy uses microwaves. maser: microwave amplification by stimulated emission of radiation 受激辐射微波放大器 laser: light amplification by stimulated emission of radiation 受激辐射光放大器 * 19 Microwave frequency bands The microwave spectrum is usually defined as electromagnetic energy ranging from approximately 1?GHz to 1000?GHz in frequency, but older usage includes lower frequencies. Most common applications are within the 1 to 40?GHz range. Microwave Frequency Bands as defined by the Radio Society of Great Britain in the table below: * Table 3.1 Table 3.1 Microwave frequency bands Designation Frequency range Designation Frequency range L band 1 to 2?GHz Q band 30 to 50?GHz S band 2 to 4?GHz U band 40 to 60?GHz C band 4 to 8?GHz V band 50 to 75?GHz X band 8 to 12?GHz E band 60 to 90?GHz Ku band 12 to 18?GHz W band 75 to 110?GHz K band 18 to 26.5?GHz F band 90 to 140?GHz Ka band 26.5 to 40?GHz D band 110 to 170?GHz * * 4 These slots act as an array and have the highest directivity when the antenna has an air dielectric and decreases as the antenna is loaded by material with increasing relative dielectric constant. 这些狭缝就像一个阵列，当天线使用空气电介质时方向性最好，但是当天线的负载材料的相对介电常数增加时方向性会减弱。 * 5 An advantage inherent to patch antennas is the abilit