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Instead of an array antenna, the received signals of only one multiarm spiral antenna combined with a modeformer circuit can be used advantageously for array signal processing, furthermore the radiation patterns of the different spiral antenna modes can be assumed as frequency independent in a first step. But for high accuracy, the remaining frequency and polarization dependencies must be taken into...
This document describes the further development of a surface/volume fast integral equation solver for the effective characterization of Planar-3D structures in a multilayered environment consisting of an arbitrary number of planes carrying microstrip/stripline structures which can be connected with arbitrary vertical currents. For interactions with vertical volume currents, extended spectral domain...
This paper focuses on generic metallic cavities, which are filled fully or partly with dielectric materials, and shows simulated as well as measured data. Also, scattering centers are visualized, which illustrates the relevant propagation paths graphically and provides a better understanding of the underlying physical phenomena.
This paper deals with a 3D inverse synthetic aperture radar (ISAR) imaging technique using a cylindrical scanning plane in the near-field of the radar target, where the resulting 3D images are displayed on sheets perpendicular to the scanning cylinder axis. Besides of a very detailed scattering center analysis of targets with arbitrary shapes, the method allows in a second step the extraction of the...
In the last years, the performance of integral equation solvers based on the Greenpsilas function of planar multilayered media could be further increased especially by reducing the numerical complexity of the standard method of moments (MoM) with the help of fast integral equation techniques employing an efficient matrix-vector product evaluation within the iterative solution process. These methods...
For accurate scattering computations in the far-field of flat finite objects, field based ray optical methods cannot be used directly, since the finiteness of the objects is not considered in the formulations. In this paper, planar near-field scanning techniques are used to overcome this problem. In particular, scattered ray optical fields are first computed in a scanning plane in the near-field region...
The global positioning system (GPS) plays nowadays an outstanding role in positioning finding and navigation for both military and civil applications. However, typical commercial GPS antennas mostly show only a small bandwidth of about 20 MHz making them rather sensitive with regard to variations of geometrical and material parameters. Therefore we have developed stacked microstrip antennas for the...
In this paper, the hybrid finite element - boundary integral - multilevel fast multipole method - uniform geometrical theory of diffraction (FEBI-MLFMM-UTD) technique is extended in order to efficiently overcome the drawbacks of ray optical methods in predicting scattered far-fields. This is obtained using planar near-field scanning techniques for dealing with ray optical terms of the scattered field...
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