The Distortion Characteristics of a Pulse Wave Propagating through Fog Medium at Millimeter Wave Band
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The Distortion Characteristics of a Pulse Wave Propagating through Fog Medium at Millimeter Wave Band Jiying Huang & Wang He & Shuhong Gong
Received: 16 June 2007 / Accepted: 27 June 2007 / Published online: 17 July 2007 # Springer Science + Business Media, LLC 2007
Abstract When a pulse wave propagates through fog, the effects of distortion, being severer at millimeter wave band, is caused by fog because of its dispersive property. The transfer function of a pulse signal is obtained by the theory of radio wave propagation; the complex envelope is deduced by the solution of Fourier integral. The broadening and compressing effects of a pulse wave are discussed. The variations of distortion effects with pulse-width, propagation distance and visibility of fog are found. As an example, the simulating and calculating results of distortion effects for Gaussian pulse at millimeter wave band are given. Keywords Distortion characteristics . Pulse wave . Fog medium
1 Introduction The electron system working at millimeter wave band is widely used in communication, radar and remote sensing and so on, because of its virtues of small volume, light weight, wide bandwidth etc, whose working state is pulse wave with wide frequency band. The designing and using of millimeter wave band systems need to predict the propagation effects of a pulse wave through bad environments, such as rain, fog, dust, smog and snow etc. So, the theory about the pulse wave at millimeter wave band propagating through continuous or discrete random medium has been paid more and more attention [1, 2]. This paper mainly discusses the distortion effects when the pulse waves at millimeter wave band pass through the fog medium. Fog is composed of many suspended water drops at the bottom of atmosphere, which can be divided into advection fog and radiation fog based on the terrain and the forming mechanism. Fog can be classified into a heavy fog, if visibility is less than 50 m; a moderate fog, if visibility is less than 200 m; a mist, if visibility is less than 500 m, according to the visibility and liquid water content [3]. J. Huang (*) : W. He : S. Gong School of Science, Xi’dian University, Xi’an 710071, People’s Republic of China e-mail: [email protected]
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Int J Infrared Milli Waves (2007) 28:889–899
A heavily attenuation and phase shift of a pulse signal can be caused by fog, and the velocity of a signal with different frequencies is different, because of the dispersive property of fog, which makes the distortion effects of a pulse serious, the ratio of signal to noise reduced, the transmitting velocity of a signal slow, error rate increase, and even makes communication system into interruption. So it is important to study the distortion effects of a pulse wave through fog, and the study results about that is seldom. In this paper, the transfer function of a pulse signal is obtained by the theory of radio wave propagation; the pulse complex envelope is deduced by the solution of Fourier integral. The broadening and compressing effects of a pulse
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