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Antenna Radar Cross-Section, IEE Colloquium on

Date 7 May 1991

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Displaying Results 1 - 9 of 9
  • Computation of the RCS of reflector antennas by field correlation

    Page(s): 2/1 - 2/4
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (188 KB)  

    Describes a method of calculating the radar cross-section of single or multiple reflector antennas by means of the `field correlation theorem' of Wood (1980). The method is based on the physical optics approximation, and enables both direct and `indirect' scattering (i.e. scattering by an object seen in a reflector) to be calculated as a surface integral over the scatterer. A similar correlation integral accounts for blockage of one reflector by another. In the case of an axisymmetric reflector antenna, the fields set up within the antenna volume by an incident plane wave can be computed using spherical wave expansions. Using this approach, the various contributors to the RCS of typical single and dual reflector antennas can be computed. The strongest reflections in the region of the main beam come from the feed horn, which, unfortunately, is the most difficult component to model accurately. An approximate technique is described which includes the reflection due to cylindrical modes which are cut off at the throat of the horn, together with the effect of induced currents in the conducting flange View full abstract»

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  • Microwave imaging of antenna RCS sources

    Page(s): 5/1 - 5/5
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (208 KB)  

    Microwave metrology of antennas is widely established for commissioning, quality assurance and diagnosis. Conventional schemes utilise the antenna as an active device in either transmit or receive mode. In a new approach to imaging structure the authors have studied the antenna as a passive scatterer from the point of view of its RCS. In this mode, the antenna response to an incident wavefront is dependent on its load View full abstract»

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  • A variational approach to the prediction of antenna RCS

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    Summary form only given. Except in special circumstances, calculation of the radar cross-section (RCS) of scattering objects relies on the numerical solution of integral equations through a suitable approach, such as the method of moments. However, if the integral equations for the scattering of the electromagnetic radiation can be formulated in terms of a variational principle the effects of distortions in the scattering objects may be accounted for. In addition, if an iterative approach is adopted the RCS of bodies of size of order of a wavelength can also be calculated. This approach is often more computationally efficient than the traditional method of moments calculation. The general application of variational techniques to the calculation of radar cross-sections is reviewed. Illustrations of the technique are given by considering the scattering from a distorted dihedral corner reflector and a thin wire representing two different classes of antenna View full abstract»

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  • IEE Colloquium on `Antenna Radar Cross-Section' (Digest No.096)

    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (60 KB)  

    The following topics were dealt with: variational approach to antenna RCS prediction; RCS of reflector antennas, field correlation; RCS of feed forms and reflector antennas; band pass radomes for RCS reduction; RCS sources microwave imaging; RCS of antennas on missile-like body; test fixture based antenna scattering measurements; and active array RCS View full abstract»

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  • Band pass radomes for reduced RCS

    Page(s): 4/1 - 4/9
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (276 KB)  

    A frequency selective surface (FSS) comprising a square grid and a hexagonal array of discs is proposed as a means of reducing the radar cross section (RCS) of a radar bay over a wide (2 GHz to 14.6 GHz) frequency bandwidth. Results are presented in terms of transmission loss for an `A' -type sandwich radome consisting of 2 FSS layers for normal and non-normal incidence. A single FSS layer on a GRP flat panel is also considered. Good agreement is found between the predicted and measured results. It is found that the proposed FSS is relatively insensitive to angles of incidence and polarisation between 3.8 GHz and 10.1 GHz. Parametric studies have indicated versatility of the proposed structure View full abstract»

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  • The RCS of antennas on a missile-like body

    Page(s): 6/1 - 6/5
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (232 KB)  

    Describes one of the major activities using Roke Manor's anechoic chamber RCS measurement facility. This is a component of Roke Manor's activity in the measurement and prediction of radar signature and stealth characteristics. In particular, a study of the RCS of antennas is described-prompted initially by general interest, and by specific concerns, regarding the effects of mounting antennas on a missile-like body. The material presented describes the anechoic chamber, the measurement equipment and the results of a measurement study intended to investigate the phenomena. The results are divided into two sections. These describe some basic mechanisms, and specific results for the antennas and target body involved. Some precise details, such as target shape, measurement frequencies and absolute RCS levels are referred to only in general terms View full abstract»

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  • Text-fixture-based antenna scattering measurements

    Page(s): 7/1 - 7/5
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (260 KB)  

    Text fixtures are commonly used to measure the radar cross-section (RCS) of flush-mounted antennas. These test fixtures are typically designed to provide a clutter-free region in which the antenna can be mounted. In addition, the test fixture provides an electromagnetic environment for the antenna which is similar to that found in the final application. Proper design of these test fixtures must take into account factors such as positioning subsystem capabilities, signal processing capabilities, and desired measurement sensitivity and accuracy. Once the test fixture design is established, proper test planning will yield the maximum amount of diagnostic information from each measurement View full abstract»

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  • RCS of reflector antennas and feed horns

    Page(s): 3/1 - 3/4
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (112 KB)  

    Considerable interest has been given to the reduction of the radar cross-section of military platforms. Careful design of the platform geometry and the judicious use of radar absorbent materials has resulted in significant reduction of the RCS response. As a result, attention has been given to the characterisation of the onboard sensors in order that they do not become the predominant source of reflection. Of particular importance is the RCS of high gain tracking antennas, since they may be directed at and locked onto a threat, providing a constant return to the radar View full abstract»

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  • Calculation of radar cross section for an active array

    Page(s): 8/1 - 8/4
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (164 KB)  

    Considers an active array antenna consisting of open ended waveguide elements, fed individually by active transmit/receive modules. Such an array may be required to operate in environments where other radars are attempting to locate it. These other radars could be aboard hostile ships or homing missiles. The way in which the active array scatters incident waves (its radar cross section) is therefore of considerable importance. A method developed for calculating the RCS of an array of open ended waveguides is described. The RCS considered is monostatic: only the reflected energy propagating back in the incidence direction is evaluated. This is the energy actually received by an observing radar. It is important to bear in mind that a monostatic RCS pattern is not equivalent to a far field pattern in that the `area under the curve' does not correspond to total scattered power as it does with a far field pattern. The theory is compared with results from RCS measurements of a test array and shown to be in good agreement View full abstract»

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