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1、RF 和微波光纤设计指引Name: Class: Student NO.: 1 RF and Microwave Fiber-Optic Design Guide Agere Systems Inc., through its predecessors, began developing and producing lasers and detectors for linear fiber-optic links nearly two decades ago. Over time, these optoelectronic components have been continually re
2、fined for integration into a variety of systems that require high fidelity, high frequency, or long-distance transportation of analog and digital signals. As a result of this widespread use and development, by the late 1980s, these link products were routinely being treated as standard RF and microw
3、ave components in many different applications. There are several notable advantages of fiber optics that have led to its increasing use. The most immediate benefit of fiber optics is its low loss. With less than 0.4 dB/km of optical attenuation, fiber-optic links send signals tens of kilometers and
4、still maintain nearly the original quality of the input. The low fiber loss is also independent of frequency for most practical systems. With laser and detector speeds up to 18 GHz, links can send high-frequency signals in their original form without the need to downconvert or digitize them for the
5、transmission portion of a system. As a result, signal conversion equipment can be placed in convenient locations or even eliminated altogether, which often leads to significant cost and maintenance savings. Savings are also realized due to the mechanical flexibility and lightweight fiber-optic cable
6、, approximately 1/25 the weight of waveguide and 1/10 that of coax. Many transmission lines can be fed through small conduits, allowing for high signal rates without investing in expensive architectural supports. The placement of fiber cable is further simplified by the natural immunity of optical f
7、iber to electromagnetic interference (EMI). Not only can large numbers of fibers be tightly bundled with power cables, they also provide a uniquely secure and electrically isolated transmission path. The general advantages of fiber-optics first led to their widespread use in long-haul digital teleco
8、mmunications. In the most basic form of fiber-optic communications, light from a semiconductor laser or LED is switched on and off to send digitally coded information through a fiber to a photodiode receiver. By comparison, in linear fiber-optic systems developed by Lucent, the light sent through th
9、e fiber has an intensity directly related to the input electrical current. While this places extra requirements on the quality of the lasers and photodiodes, it has been essential in many applications to transmit arbitrary RF and microwave signals. As a result, tens of thousands of Agere Systems tra
10、nsmitters are currently in use. The information offered here examines the basic link components, provides an overview of design calculations related to gain, bandwidth, noise, and dynamic range 2 and distortion. A section on fiber-optic components discusses a number of key parameters, among them wav
11、elength and loss, dispersion, reflections, and polarization and attenuation. Additional information evaluates optical isolators, distributed-feedback lasers and Fabry- Perot lasers, predistortion, and short- vs. long-wavelength transmission. One of linear optical fiber relation main usages or receiv
12、es between the electronic installation and the remote localization antenna in the transmission transmits RF and the microwave signal 。 Because of the optical fiber chain flexibility， possibly can for the simulation or digital signal design some antennas， including the military and the commercial com
13、munications satellite， the global localization satellite， the remote sensing with traces the lighthouse ，or wireless cell network 。 Another kind of type chain is the optical fiber delay line， installs in a package it including a transmitter， a receiver ，with long textile fiber 。It may provide the lo
14、ng delay time, high band width, with low weight. These high-frequency RF and the microwave product has obtained benefits from the use linear optical fiber equipment cable television raging tide middle earth. In here, the textile fiber expands the TV signal the transmitting range, improves their qual
15、ity and the system reliability, but when merely only has the electric cable, even with the system which used compares has saved the expense In each of these applications, as well as many others, the Agere Systems transmitters and receivers comprising the links are similar and can be treated as stand
16、ard microwave components. Focusing on these common elements, this design guide describes the general technical considerations and equations necessary for engineers to choose the most appropriate Agere Systems components for their systems. These equations also have been incorporated into various programs, which an Agere Systems applications engineer can use to provide an analysis for a specific link application. Figure 1 shows the three primary components in
