New block ILU preconditioner scheme for numerical analysis of very large electromagnetic problems

Large electromagnetic scattering and radiation problems are tackled by iterative solvers, which require the use of huge preconditioners. Most often, the incomplete LU decomposition (ILU) of the preconditioner is applied to the system matrix at each iteration. However, the preconditioner ILU cannot be done in-core when the size of the preconditioning matrix exceeds the available memory. This paper presents a new preconditioning scheme to do the preconditioner ILU in small blocks that fit in core memory. The resulting approach allows the solution of very large problems in small computers.Peer Reviewe

Accurate numerical modeling of the TARA reflector system

The radiation pattern of the large parabolic reflectors of the Transportable Atmospheric RAdar system (TARA), developed at Delft University of Technology, has been accurately simulated. The electric field integral equation (EFIE) formulation has been applied to a model of the reflectors including the feed housing and supporting struts, discretised using the method of moments. Because the problem is electrically large (the reflector has a diameter of 33λ) and nonsymmetrical, this lead to a badly conditioned linear system of approximately half a million unknowns. In order to solve this system, an iterative solver (generalized minimum residual method) was used, in combination with the multilevel fast multipole method. Because of the bad conditioning, the system could only be solved by using a huge preconditioner. A new block-incomplete LU preconditioner (ILU) algorithm has been employed to allow for efficient out-of-computer core memory preconditioning.Peer Reviewe

Ultra-wideband 3D image processing for improving landmine detection with GPR, Journal of Telecommunications and Information Technology, 2005, nr 2

This paper describes a new landmine detection algorithm starting from high resolution 3D ground penetrating radar (GPR) images. The algorithm consists of two procedures, object detection and object classification; both strongly depend on the properties of 3D GPR images. The algorithm has been tested on data measured with an ultrawideband (UWB) video impulse radar (VIR) system developed by the International Research Centre for Telecommunications and Radar (IRCTR). It was found that the algorithm is able to detect all landmines (including difficult to detect M14 mines) and classifies almost all landmines correctly with a large reduction in the number of false alarms caused by clutter. It turns out that for clutter removal it is most effective to eliminate detected objects with a small height

Doppler polarimetric ground clutter identification and suppression for atmospheric radars based on co-polar correlation, Journal of Telecommunications and Information Technology, 2001, nr 4

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)

A dedicated computer system for FM-CW radar applications, Journal of Telecommunications and Information Technology, 2001, nr 4

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 s. Radar system control includes the timing and the settings of the radar system together with linearity correction of the sweep oscillator

Multi-band antennas with integrated circuitry in mobile phones

Focus of this article is on the co-design of multi-band antennas and RF circuitries. Simple circuitry can be used for matching in order to extend the antenna bandwidth. Some new design concepts are presented. Improved antenna performance has been obtained