No. 4 (2001)
Published:
2001-12-30
ARTICLES FROM THIS ISSUE
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Doppler polarimetric ground clutter identification and suppression for atmospheric radars based on co-polar correlation
Abstract
A new clutter suppression technique that uses both Doppler and polarimetric information is presented. Polarimetric properties of the target and clutter are calculated per Doppler frequency cell and based on this information clutter suppression is performed. This new clutter suppression technique is demonstrated with radar measurements of precipitation made by the Delft atmospheric research radar (DARR).
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Constant co-polarized echo curves on the Poincare sphere
Abstract
A set of useful formulae has been presented allowing for computation of the equipower curves on the Poincare sphere of the co-polarized radar returns for both mono- and bi-static scatterings.
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24 GHz radar sensors for automotive applications
Abstract
Automotive radar systems using integrated 24 GHz radar sensor techniques are currently under development [1]. This paper describes a radar network consisting of four sensors distributed behind the front bumper of an experimental car. Each single sensor measures the target range with high accuracy. A multilateration technique is used in the radar network for precise azimuth angle estimation even in multiple-target situations. The system performance is shown in real traffic situations for parking aid, stop
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Generalized radar/radiometry imaging problems
Abstract
In the paper the results of spatio-temporal imaging simulation based on radar, synthetic aperture radar (SAR) and radiometry systems are presented. The analytical relationship between object scattering/emitting and the formed image is given and the general approach for the description of imaging system by means of Frendholm equation solution is developed. The potential limit of image resolution based on Rao-Cramer inequality is estimated.
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A dedicated computer system for FM-CW radar applications
Abstract
In this paper, a DSP based computer system for FM-CW radar applications is described. Besides data acquisition and storage, the computer system will also be used for front-end data processing and system control. Processing includes filtering and clutter suppression. The radar for which the computer is designed is a multi parameter atmospheric profiler capable of doing Doppler and polarimetric measurements. The computer system will allow for a measurement of the full polarimetric scattering matrix over 512 range cells and 512 Doppler cells in 2
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The simple analysis method of nonlinear frequency distortions in FMCW radar
Abstract
The paper presents a simple method for estimating nonlinear frequency distortions of linear frequency modulated (LFM) signals used in FMCW radars. This method, derived from the polynomial model of the nonlinear FM signal phase, is based on finding the maximum of two-dimensional chirp-like transform of the IF video signal. The IF signal is obtained by mixing transmitted FM signal with its delayed copy. Using suggested transform we show that the presented method is able to detect and classify signal distortions.
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The priority assignment for detected targets in multifunction radar
Abstract
In a multifunction radar there is necessity to manage its very limited resources. This management should concern, among others, detected targets importance description. So information of those with lower priority will be refreshed more rarely. Presented paper describes system that assigns ranks for all detected objects in real time and then puts targets in order of priority. The system is based on structure of artificial neuron. Methods of neuron learning are discussed.
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Geometrical representation of a monochromatic electromagnetic wave using the tangential vector approach
Abstract
The aim of this work is to develop a coherent polarimetric model and to find a geometrical description of a monochromatic wave. The spinor form of the electrical field, its links to the coherency matrix and the Poincare’ sphere are introduced with the aim to obtain a geometrical representation of the spinor. It consists, from the “polarization point of view”, on the polarization vector and a tangential plane to the Poincare’ sphere where it is possible to visualize the zero phase.
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New type of microstrip antenna with ferroelectric layer
Abstract
new type of microstrip antenna is proposed using a voltage-controlled ferroelectric thin tape in the multilayered structure. This paper presents the ferroelectric thin tape, its theoretical analysis and design. The results indicate that this concept has many advantages, is very practical and promising. It gives possibilities of several applications, e.g. in smart antennas.
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A broadband uniplanar quasi-Yagi antenna - parameter study in application to a spatial power combiner
Abstract
A parameter study is performed of a broadband uniplanar quasi-Yagi antenna with regard to its design and use in a~spatial power combiner. A 3D full-wave electromagnetic field analysis is applied to identify parameters, which mostly affect the design frequency and operational bandwidth of this antenna. Optimal design conditions are determined. Using these design criteria a passive spatial power combiner employing trays of back-to-back connected quasi-Yagi antennas is developed. This combiner is investigated in terms of insertion losses and field uniformity, which are key factors in obtaining high power combining efficiency.
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Photonic band gaps in complex layered arrays
Abstract
Reflective and transmitting properties of several layers of double-periodic arrays are studied. In the arrays, elements are conducting inclusions of various shapes. It is shown that in these structures all the phenomena recently found in dense wire grids with periodical defects (so-called photonic band gap structures) can be observed and explained in simple terms of inter-layer and inclusion resonances. Frequency-selective (with two and more stop bands) and polarization transformation properties of these arrays are demonstrated.
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Antennas of vehicles landing on a planet surface
Abstract
The antenna systems designed under the international projects ``Mars-96`` and ``Phobos`` are described. The antenna system of Small station landing on Mars, in flight is packed under protective petals of the station and is opened on a surface with the help of flexible legs. The original scheme of excitation in the form of compact strip-geometry is described. The antenna system of the mobile vehicle landing on Phobos, provides the omnidirectional pattern on the basis of the combination of antenna methods with methods of processing of the received signal. The high efficiency of the antenna results from its construction in the form of an active antenna.
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Characteristics of the indoor propagation channel in 1.9 GHz band
Abstract
This paper presents results of propagation measurements carried out in the frequency range 1.8;nbsp;-
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Distortion and noise problems of subcarrier multiplexed optical systems
Abstract
In this paper investigation of subcarrier multiplexed optical subsystems for optically supported communication systems is presented. Noise and spurious free dynamic range are the main parameters, which are determined by the applied optical transmission. The frequency dependence of these parameters and optimal frequency chosen is presented.
