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Using a generic electromagnetic model based on the spherical vector harmonics, we provide the Cramer-Rao lower bound (CRB) for direction-on-arrival (DOA) and polarization estimation with arbitrary multiport antennas. By reciprocity, the receiving multiport antenna is characterized in terms of the transmission matrix from incident voltage waves to multipole(More)
Extraordinary transmission through subwavelength apertures is usually observed in a narrow bandwidth range, and the transmission outside this range is low, in agreement with classical results. The analysis presented here is based on the Babinet's principle and hence scattering by the complementary structure, where the apertures are replaced by finite(More)
We have developed an Internet-based tool for remote realtime auscultation. The device was based on a commercially available electronic stethoscope and a PC which digitized and transmitted the signals. A voice and video channel were also available. The remote auscultation tool was evaluated between two sites in Sweden separated by a distance of 500 km. A(More)
Digital holography has some desirable properties for refractometry of microscopic objects since it gives phase and amplitude information of an object in all depths of focus from one set of exposures. We show that the amplitude part of the image can be used to observe how the Becke lines move between different depths of focus and hence determine whether an(More)
We demonstrate a digital holographic method in which two different substances in a blend are discerned. The method requires only one set of exposures and one reconstruction in the plane of focus. The phase is unwrapped by Flynn's discontinuity algorithm to produce an image of the variation of the optical distance of the illuminating wave. Objects with(More)
1 This series is divergent, therefore we may be able to do something with it. Oliver Heaviside Nature laughs at the difficulties of integration. Abstract In the present paper an iterative time-reversal algorithm, that retrofocuses an acoustic wave field to its controllable part is established. For a fixed temporal support, i.e., transducer excitation time,(More)
In this paper, quantitative dielectric image reconstruction based on broadband microwave measurements is investigated. A time-domain-based algorithm is derived where Debye model parameters are reconstructed in order to take into account the strong dispersive behavior found in biological tissue. The algorithm is tested with experimental and numerical data in(More)
A passive system is one that cannot produce energy, a property that naturally poses constraints on the system. In this paper there is a review of some results on linear, time translational invariant, continuous, causal and passive systems, where it turns out that Herglotz functions are related to the Fourier transform of the impulse response of such(More)
An optimization approach to a multi-dimensional acoustic inverse problem in the time domain is considered. The density and/or the sound speed are reconstructed by minimizing an objective functional. By introducing dual functions and using the Gauss divergence theorem, the gradient of the objective functional is found as an explicit expression. The(More)