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一、前言 毫米波系统经历长期缓慢的发展以后,近几年来获得迅速进步。目前正在研制各式各样的系统,例如跟踪雷达,导弹寻的器、辐射计及短程通信等。与微波系统和电光系统相比,毫米波系统有许多优点。比之前者,体积小、重量轻、精度好、分辨率高、天线尺寸小;比之后者(或是红外系统)穿透云、烟和灰尘的能力大为改善。另外,在毫米波段,由于频率随大气衰减的特点,产生了各种独特的应用,例如,62GHz附近的高吸收线可用来进行保密通信,而中心频率在35、94、140及230GHz附近的低衰减窗口,则可用来大大增加通信的信息容量。
I. INTRODUCTION Millimeter-wave systems have enjoyed rapid progress in recent years after experiencing long-term slow development. A wide variety of systems are being developed, such as tracking radar, missile seekers, radiometers and short-range communications. Millimeter wave systems have many advantages over microwave and electro-optical systems. Compared to the former, small size, light weight, good accuracy, high resolution, small antenna size; than the latter (or infrared system) greatly improved the ability to penetrate clouds, smoke and dust. In addition, in the millimeter wave band, various unique applications arise because of the frequency attenuation with the atmosphere. For example, the high absorption line near 62 GHz can be used for secure communication. The center frequency is low around 35, 94, 140 and 230 GHz Attenuation window, can be used to greatly increase the communication information capacity.