Tài liệu SMART ANTENNAS ppt

[...]... Omnidirectional antennas radiate equal amounts of power in all directions Also known as isotropic antennas, they have equal gain in all directions Directional antennas, on the other hand, have more gain in certain directions and less in others A direction in which the gain is maximum is referred to as the antenna boresight The gain of directional antennas in the boresight is more than that of omnidirectional antennas, ... current demand for smart antennas to increase channel capacity in the fast-growing area of mobile communications has reignited the research and development efforts in this area around the world [God97] This book aims to help researchers and developers by providing a comprehensive and detailed treatment of the subject matter Throughout the book, references are provided in which smart antennas have been... 1.3 Power Pattern 1.4 Beam Steering 1.5 Degree of Freedom 1.6 Optimal Antenna 1.7 Adaptive Antenna 1.8 Smart Antenna 1.9 Book Outline References Widespread interest in smart antennas has continued for several decades due to their use in numerous applications The first issue of IEEE Transactions of Antennas and Propagation, published in 1964 [IEE64], was followed by special issues of various journals... pattern For adaptive antennas, the conventional antenna pattern concepts of beam width, side lobes, and main beams are not used, as the antenna weights are designed to achieve a set performance criterion such as maximization of the output SNR On the other hand, in conventional phase-array design these characteristics are specified at the time of design 1.8 Smart Antenna The term smart antenna incorporates... of Antennas in Wireless Communications, CRC Press, Boca Raton, FL, 2002 Hay85 Haykin, S., Ed., Array Signal Processing, Prentice Hall, New York, 1985 Hay92 Haykin, S et al., Some aspects of array signal processing, IEE Proc., 139, Part F, 1–19, 1992 Hud81 Hudson, J.E., Adaptive Array Principles, Peter Peregrins, New York, 1981 IEE64 IEEE, Special issue on active and adaptive antennas, IEEE Trans Antennas. .. and adaptive antennas, IEEE Trans Antennas Propagat., 12, 1964 IEE76 IEEE, Special issue on adaptive antennas, IEEE Trans Antennas Propagat., 24, 1976 IEE85 IEEE, Special issue on beamforming, IEEE J Oceanic Eng., 10, 1985 IEE86 IEEE, Special issue on adaptive processing antenna systems, IEEE Trans Antennas Propagat., 34, 1986 IEE87a IEEE, Special issue on adaptive systems and applications, IEEE Trans... environment Chapter 8 considers multiple antenna systems and presents various diversity-combining techniques References App76 Applebaum, S.P., Adaptive arrays, IEEE Trans Antennas Propagat., 24, 585–598, 1976 Com88 Compton Jr., R.T., Adaptive Antennas: Concepts and Performances, Prentice Hall, New York, 1988 d’A80 d’Assumpcao, H.A., Some new signal processors for array of sensors, IEEE Trans Inf Theory, 26,... optimal antennas The antenna pattern in this case has a main beam pointed in the desired signal direction, and has a null in the direction of the interference Assume that the interference is not stationary but moving slowly If optimal performance is to be maintained, the antenna pattern needs to adjust so that the null position remains in the moving interference direction A system using adaptive antennas. .. Antenna The term smart antenna incorporates all situations in which a system is using an antenna array and the antenna pattern is dynamically adjusted by the system as required Thus, a system employing smart antennas processes signals induced on a sensor array A block diagram of such a system is shown in Figure 1.2 © 2004 by CRC Press LLC Sensor 1 Sensor 2 Processor Output Sensor L Additional Information... adaptive antenna array processing and their application to mobile communications Included among his many publications are two significant papers in the Proceedings of the IEEE Prof Godara edited Handbook of Antennas for Wireless Communications, published by CRC Press in 2002 Professor Godara is a Senior Member of the IEEE and a Fellow of the Acoustical Society of America He was awarded the University College . Saroj © 2004 by CRC Press LLC Preface Smart antennas involve processing of signals induced on an array of sensors such as antennas, microphones, and hydrophones interference. The smart antenna field has been a very active area of research for over four decades. During this time, many types of processors for smart antennas