M. Ivashina

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In recent years, Compressive Sensing has attracted considerable attention in various areas of antennas and electromagnetics, including the synthesis of sparse array antennas. The CS synthesis of arrays achieves higher accuracy than analytical methods and allows for the fast and deterministic design of large complex arrays, without resorting to(More)
—The design of a push-broom multi-beam radiometer for future ocean observations is described. The radiometer provides a sensitivity one order of magnitude higher than a traditional conical scanning radiometer, and has the big advantage of being fully stationary relative to the satellite platform. Thanks to a dense focal plane array and a dedicated(More)
A general framework is presented for modeling direction-dependent effects that are also baseline-dependent, as part of the calibration and imaging process. Within this framework such effects are represented as a parametric linear model in which basis functions account for direction dependence, whereas expansion coefficients account for the baseline(More)
We consider the application of the Characteristic Basis Function Pattern (CBFP) method to calibrate for direction-dependent gain effects of the LOFAR Low Band Antenna (LBA) array. The use of array-based calibration models, as opposed to element-based calibration models, is proposed in order to reduce the number of solvable beam model parameters.
The performance of a dual-polarized quad-mode antenna, representing a potential array antenna element for wide scan-angle applications, is assessed. This analysis is carried out by investigating the utilization of the four available Transverse Electromagnetic (TEM) excitation modes, when beamforming for maximum gain, Signal-to-Noise ratio (SNR), and(More)
Initial optimization results for the wide-band Eleven antenna and Quadruple-Ridged Flared Horn (QRFH), designed to operate as the reflector antenna feeds at 350 - 1050 MHz, are presented and discussed in the context of the next generation radio telescope - the Square Kilometer Array (SKA). First, we describe the procedure that has been developed to carry(More)
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A dual-mode antenna design, utilizing a combination of differential- and common-mode excitations, is presented. This antenna offers the possibility to complex-combine both modes in order to obtain a near-hemispherical Field of View (FoV) coverage. A Single-Ended (SE) to Mixed-Mode (MM) transformation model is introduced to determine the MM radiation(More)
We discuss how to evaluate SKA technology options with regard to science output quality. In this work we will focus on polarimetry. We review the SKA specification for polarimetry and assess these requirements. In particular we will use as a illustrative case study a comparison of two dish types combined with two different feeds. The dish types we consider(More)