A portable multisensor frequency modulated continuous radar (FMCW) networked radar concept is presented for the localization of persons trapped in debris in building collapse scenarios. A 2-D ...localization algorithm is evaluated in a field test to demonstrate successful localization detection of respiration micromovements.
A configuration of composite resonators consisting of three split-ring resonators is proposed to obtain a triple-band response with two transmission zeros between the passbands. Two new topologies ...are presented to design triple-band filters with controllable responses. A systematic filter design approach is presented based on a filter coupling model. The model is established to enable triple-band filter design with controlled passbands. Two methods are proposed and compared for the extraction of filter parameters. Coupling between nonadjacent elements is considered in the model and shown to have a significant effect. By changing the orientation of the coupled composite resonators, it is possible to introduce additional transmission zeros. Two sixth-order filter examples illustrate the use of the coupling model with the filter design approach to design filters with specified responses. The limitations of this filter topology are discussed.
In this work, a multi-mode Hilbert-fork resonator consisting of two dual-mode resonators is presented. The behavior of the proposed configuration is analyzed in detail. To demonstrate the potential ...of the proposed resonator, tri-band bandpass and bandstop filters operating at 2.4/3.5/5.2 GHz have been designed, fabricated and measured. Both filters are characterized by good performances and very compact size of only 0.21λ g × 0.11λ g and 0.22λ g × 0.1λ g , respectively.
The implementation of a recent new hybrid integral-equation/vector finite-element method formulation applicable to inhomogeneous obstacle scattering in hollow waveguide, requiring discretization just ...of the obstacle, is presented. The integral equation links the given incident modes with the discontinuity-surface electric and magnetic fields. The finite-element equation is expressed in terms of the entire magnetic and surface electric field of the obstacle. Compatible vector finite-element basis function expansions are inserted, resulting in a pair of matrix equations soluble for the unknown electric and magnetic basis coefficients. Corresponding two-port scattering parameters are further derived. Test cases of posts in the TE 10 waveguide, with details of the matrix constructions, are described. Numerical results verified against an established commercial code are given. The ability to model inhomogeneous, lossy, and multiple scatterers is demonstrated
Common mode (CM) currents are a major source of interference in electrical and electronic systems. Cable trays are often used to shield cables from unwanted CM electromagnetic interference, and their ...shielding characteristics are defined in terms of transfer impedance. We present the measurement and modeling of nonmagnetic U-shaped cable trays from 300 kHz to 30 MHz. A calibrated vector network analyzer in a screened environment is required for the high dynamic range measurements. We use method of moments simulations to determine the transfer impedance and mutual inductance within the interior region of a cable tray. We refined the modeling after detailed attention to the code. The computational and measured data are in good agreement. We propose the simulation as a means to predict the magnetic fields, mutual inductance, and transfer impedance associated with victim cable loops in the cross section of nonmagnetic cable trays to frequencies well beyond our studied range of 30 MHz.
A dual-mode resonator is presented for tunable wideband filters, which allows tunability in both the centre frequency and bandwidth. It is based on a new perturbation arrangement in a ring-resonator ...that is electronically tuned with varactor diodes. A filter is designed for a radio astronomy receiver application. It consists of 6 cascaded dual-mode resonators with a 49% bandwidth in the L-band. High selectivity and low insertion losses are achieved. The centre frequency is tunable by 9% and the bandwidth by 25.3%. This design is unique in that it achieves wide bandwidth, is realisable in microstrip and tunable in both the centre frequency and bandwidth.
Thesis (PhD)--University of Stellenbosch, 2004.
ENGLISH ABSTRACT: The implementation and verification of a recently proposed Huy gens' principle in hollow;
lossless waveguide is described. The ...extended Huygens' principle is applicable;
to the scattering effect of arbitrary obstacles in waveguide and allows the coupling;
of a volume Finite Element discretization with a quasi Method of Moments surface;
element approach. A review of the technique is given and expressions for the two port;
scattering parameters are derived. The implementation is restricted to posts in rectangular;
waveguide, although the technique may also be applied to general scattering;
problems in waveguide. Finite Elements for the volume of the obstacle are selected;
and a basis set is proposed. The elemental finite element matrices are derived for a low;
and higher order basis set, while the validity of the derivations is established by considering;
a simple waveguide example. A coupled set of matrix equations is constructed;
that can be solved for the unknown surface electric and magnetic fields and the volume;
magnetic fields. A set of test examples is chosen to verify the implementation. The;
convergence behaviour is examined for two test cases. The dissertation concludes with;
an evaluation of the technique and recommendations for future work.
AFRIKAANSE OPSOMMING: Die implementasie en verifiëring van 'n onlangs voorgestelde Huygens beginsel in;
leë golfleier word beskryf. Die uitgebreide beginsel van Huygens is van toepassing;
op die strooiingseffek van arbitrêre voorwerpe in verlieslose golfleier en beskryf die;
koppeling tussen 'n volume eindige element diskretisasie met 'n oppervlakelement;
kwasi-moment metode. 'n Oorsig oor die tegniek word gegee en uitdrukkings vir die;
tweepoort strooiingsparameters word afgelei. Die implementering word beperk tot;
penne in reghoekige golfleier, alhoewel die tegniek op algemene golfleier strooiingsprobleme;
van toepassing is. Eindige elemente word gekies vir die volume van die;
voorwerp en 'n basisfunksie versameling afgelei van bestaande basisfunksies. Lae;
en hoë orde element matrikse word afgelei en die geldigheid van die afleidings word;
nagegaan deur 'n eenvoudige golfleier probleem op te los. 'n Gekoppelde stel matriksvergelykings;
word opgestel in terme van die onbekende oppervlak elektriese en;
magnetiese velde. 'n Aantal toetsvoorbeelde word gekies om die implementasie te;
verifieer. Konvergensiegedrag word ondersoek vir twee toetsgevalle. Die proefskrif;
sluit af met 'n evaluasie van die tegniek en aanbevelings vir verdere werk.
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