Xem 1-20 trên 41 kết quả Radio waves
  • Wireless network refers to any type of computer network that is not connected by cables of any kind. It is a method by which homes, telecommunications networks and enterprise (business) installations avoid the costly process of introducing cables into a building, or as a connection between various equipment locations.[1] Wireless telecommunications networks are generally implemented and administered using a transmission system called radio waves. This implementation takes place at the physical level (layer) of the OSI model network structure....

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  • This project explores the development of a multiple input multiple output (MIMO) simulator using ray tracing techniques. This project gives an overview of ray tracing techniques, beamforming, MIMO channel models and MIMO systems. It explains the ability of MIMO systems to offer significant capacity increases over traditional wireless systems, by exploiting the phenomenon of multipath. By modelling high frequency radio waves as travelling along localized linear trajectory paths, they can be approximated as rays, just as in optics....

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  • Fundamentals of Radio Transmission In mobile radio systems, unlike wired networks, electromagnetic signals are transmitted in free space (see Figure 2.1). Therefore a total familiarity with the propagation characteristics of radio waves is a prerequisite in the development of mobile radio systems. In principle, the Maxwell equations explain all the phenomena of wave propagation. However, when used in the mobile radio area, this method can result in some complicated calculations or may not be applicable at all if the geometry or material constants are not known exactly....

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  • Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Radio wave propagation in curved rectangular tunnels at 5.8 GHz for metro applications, simulations and measurements

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  • Tuyển tập các báo cáo nghiên cứu khoa học ngành toán học được đăng trên tạp chí toán học quốc tế đề tài: Radio wave propagation in curved rectangular tunnels at 5.8 GHz for metro applications, simulations and measurements

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  • Tuyển tập các báo cáo nghiên cứu về hóa học được đăng trên tạp chí sinh học đề tài : Radio wave propagation in curved rectangular tunnels at 5.8 GHz for metro applications, simulations and

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  • Light is just one portion of the various electromagnetic waves flying through space. The electromagnetic spectrum covers an extremely broad range, from radio waves with wavelengths of a meter or more, down to x-rays with wavelengths of less than a billionth of a meter. Optical radiation lies between radio waves and x-rays on the spectrum, exhibiting a unique mix of ray, wave, and quantum properties.

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  • You will understand the physical meaning behind the mathematics of wireless signals and learn the intricacies and tradeoffs in signal selection and design.

    pdf903p dangkhoa1612 18-05-2013 76 41   Download

  • Science tries to explain a very complicated world. We are surrounded by very many objects, moving around, reacting together, breaking up, joining together, growing and shrinking. And there are many invisible things, too - radio waves, sound, ionizing radiation. If we are to make any sense of all this, we need to simplify it. We use models, in everyday life and in science, as a method of simplifying and making sense of everything we observe. A model is a way of explaining something difficult in terms of something more familiar. For example, there are many models used to describe...

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  • Crystal radio receiver - also known as crystal receiver - radio is a simple yet very common in the early days of radio industry. No batteries or other power source to an activity that uses the power received from radio waves through a very long wire antenna and high. In Vietnam, formerly known as Galen

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  • I enjoyed reading this book for a number of reasons. One reason is that it addresses high-speed analog design in the context of microwave issues. This is an advanced level book, which should follow courses in basic circuits and transmission lines. Most analog integrated circuit designers in the past worked on applications at a low enough frequency that microwave issues did not arise. As a consequence, they were adept at lumped parameter circuits and often not comfortable with circuits where waves travel in space.

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  • The wireless era was started by two European scientists, James Clerk Maxwell and Heinrich Rudolf Hertz. In 1864, Maxwell presented Maxwell's equations by unifying the works of Lorentz, Faraday, Ampere, and Gauss. He predicted the propagation of electromagnetic waves in free space at the speed of light. He postulated that light was an electromagnetic phenomenon of a particular wavelength and predicted that radiation would occur at other wavelengths as well. His theory was not well accepted until 20 years later, after Hertz validated the electromagnetic wave (wireless) propagation.

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  • In the nineteenth century, scientists, mathematician, engineers and innovators started investigating electromagnetism. The theory that underpins wireless communications was formed by Maxwell. Early demonstrations took place by Hertz, Tesla and others. Marconi demonstrated the first wireless transmission. Since then, the range of applications has expanded at an immense rate, together with the underpinning technology. The rate of development has been incredible and today the level of technical and commercial maturity is very high.

    pdf546p namde01 10-04-2013 37 17   Download

  • FREQUENCY MODULATED RADIO TRANSMITTER In Chapter 2, the amplitude of a high-frequency (carrier) sinusoidal signal was varied in accordance with the waveform of an audio-frequency (modulating) signal to give an amplitude modulated (AM) wave which could be transmitted, received, and demodulated to recover the original audio frequency signal. In frequency modulated (FM) radio, the frequency of the carrier is varied about a fixed value in accordance with the amplitude of the audio frequency.

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  • There are limits to the reach of radar signals. At the frequencies normally used for radar, radio waves usually travel in a straight line.

    pdf2p nguyen4 16-11-2009 66 12   Download

  • THE AMPLITUDE MODULATED RADIO RECEIVER The electromagnetic disturbance created by the transmitter is propagated by the transmitter antenna and travels at the speed of light as described in Chapter 2. It is evident that, if the electromagnetic wave encounters a conductor, a current will be induced in the conductor. How much current is induced will depend on the strength of the electromagnetic field, the size and shape of the conductor and its orientation to the direction of propagation of the wave....

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  • (BQ) Ebook Microwave Engineering emphasizes the fundamental concepts of Maxwell's equations, wave propagation, network analysis and design principles as applied to modern microwave engineering. Applications of microwave engineering are also changing, with increasing emphasis on commercial use of microwave technology for personal communications systems, wireless local area networks, millimeter wave collision avoidance vehicle radars, radio frequency (RF) identification tagging, direct broadcast satellite television, and many other systems related to the information infrastructure.

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  • Textbooks on radio antennas and propagation have changed little over the last 50 years. Invariably they base themselves on the famous electromagnetic equations described by James Clerk Max- well, a great nineteenth-century genius of theoretical physics (Torrance, 1982). Maxwell's equations brilliantly encompassed all the electromagnetic phenomena known by his time (except photo- electric long-wave cut-off, which remained ...

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  • Propagation in Built-up Areas Having looked at how irregular terrain a€ects VHF and UHF radio wave propagation and the e€ects of multipath, we are now in a position to discuss propagation in built-up areas. This chapter will deal principally with propagation between base stations and mobiles located at street level; propagation into buildings and totally within buildings will be discussed later. Although losses due to buildings and other man-made obstacles are of major concern, terrain variations also play an important role in many cases.

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  • What is it? RADAR to detect position of objects. Counter measures 1. ECM ( e.g. chaff cartridges) 2. Non ECM. Avoiding detection and innovating deception . RCS reductions, acoustics, thermal and other EM emissions.How is it achieved. Absorbs radar waves or deflects to other directions. Minimizes heat and other emissions from engine and other spots. Makes difficult to detect except closely.Vehicle shape and structure.Smooth edges maximum radio wave reflectors.

    ppt21p dangan91 21-12-2012 21 7   Download

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