| 1. |
- Bergman, Jan, et al.
(author)
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DARTS - Distributed Aperture Radio Telescope in Space - First Starlight Explorer
- 2018
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In: 2018 2nd URSI Atlantic Radio Science Meeting, AT-RASC 2018. - : IEEE. - 9789082598735
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Conference paper (peer-reviewed)abstract
- SBERGMANURSIATDARTS1. However, despite the strong science case for the opening up of a brand-new window on the Universe at a low radio frequency that is largely unexplored, mission proposals have been significantly challenged with the lack of flight proven technologies, to implement a space telescope using low cost small spacecraft formations. In recent years, the advent of CubeSat technologies, interplanetary missions and radio frequency inter-satellite link (ISL) technology, have improved to the point that developing a mission where a space radio telescope is formed using a constellation of small satellites is now viable, to bring unique science offerings.
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| 2. |
- Carozzi, Tobia, 1966, et al.
(author)
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Enhancing SKA Band 1 Polarimetry by Using Two Different Feed Rotations
- 2018
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In: 2018 2nd URSI Atlantic Radio Science Meeting, AT-RASC 2018. - 9789082598735
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Conference paper (peer-reviewed)abstract
- We investigate the possibility of enhancing the polarimetric performance of the Square Kilometre Array (SKA) telescope's band 1 by mounting the feeds with two different rotations relative the dish. One rotation aligns the two polarizations along the horizontal and vertical directions and the other rotation is 45 degrees to the horizontal, vertical directions. Taken together, this configuration amounts to introducing a simple and cheap type of polarization diversity. We find that such a configuration can improve polarimetry. This is important since the offset gregorian dish design employed for SKA1-mid tends to produce beam-shapes that are not rotationally symmetric, and thus polarimetry tends to vary azimuthally.
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| 3. |
- Frid, Henrik, et al.
(author)
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Determining Installation Errors for DOA Estimation with Four-Quadrant Monopulse Arrays by using Installed Element Patterns
- 2018
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In: 2018 2nd URSI Atlantic Radio Science Meeting, AT-RASC 2018. - : Institute of Electrical and Electronics Engineers (IEEE). - 9789082598735
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Conference paper (peer-reviewed)abstract
- The four-quadrant monopulse array is widely used for direction of arrival (DOA) estimation. Errors in the angle estimate are introduced when installing the array on a platform, due to unwanted reflections in the platform, as well as reflection and refraction in the radome. These installation effects are captured in the installed element patterns, which can be computed using a number of computational electromagnetics methods. In this paper, we demonstrate that the error introduced in the DOA estimate can be determined from the installed element patterns. To illustrate how the method is used, we present results for two cases: (a) BoR-array without radome and (b) BoR-array with an extended hemispherical radome. The presented method can be applied for any installation configuration, as long as the installed element patterns can be computed.
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| 4. |
- Hamnerius, Yngve, 1950, et al.
(author)
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Design of Safe Wireless Power Transfer Systems for Electric Vehicles
- 2018
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In: 2018 2nd URSI Atlantic Radio Science Meeting, AT-RASC 2018. - 9789082598735
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Conference paper (peer-reviewed)abstract
- Wireless charging of electric vehicles is convenient but in order to make it safe the exposure of humans to electromagnetic fields must be below acceptable limits. We have designed a prototype system that transmits 3 kW with an efficiency of 85% where the magnetic fields around and inside the vehicle are below the EU council recommendation of 6.25μT at 85 kHz.
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| 5. |
- Huang, S. Y., et al.
(author)
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Observations of Whistler Waves in the Magnetic Reconnection Diffusion Region
- 2018
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In: 2ND URSI ATLANTIC RADIO SCIENCE MEETING (AT-RASC). - : IEEE. - 9789082598735
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Conference paper (peer-reviewed)abstract
- Whistler waves are believed to play an important role during magnetic reconnection. In this paper, we report the simultaneous occurrence of two types of the whistler waves in the magnetotail reconnection diffusion region. The first type is observed in the pileup region of downstream and propagates away along the field lines to downstream, and is possibly generated by the electron temperature anisotropy at the magnetic equator. The second type is found around the separatrix region and propagates towards the X-line, and is possibly aenerated by the electron beam-driven whistler instability or Cerenkov emission from electron phase-space holes. Our observations of two different types of whistler waves are well consistent with recent kinetic simulations, and suggest that the observed whistler waves are the consequences of magnetic reconnection.Moreover, we statistically investigate the whistler waves in the magnetotail reconnection region, and construct the global distribution and occurrence rate of the whistler waves based on the two-dimensional reconnection model. It is found that the occurrence rate of the whistler waves is large in the separatrix region (113,1B0j>0.4) and pileup region ([B,./Bol<0.2, 161>45'), but very small in the X-line region. The statistical results are well consistent with the case study.
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| 6. |
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| 7. |
- Quevedo-Teruel, Oscar, et al.
(author)
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Implications of Higher Symmetries in Periodic Structures
- 2018
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In: 2018 2nd URSI Atlantic Radio Science Meeting, AT-RASC 2018. - : Institute of Electrical and Electronics Engineers Inc.. - 9789082598735
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Conference paper (peer-reviewed)abstract
- In this paper, we explain the concept of higher symmetries, their implications and possible applications-within electromagnetic technology.
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| 8. |
- Shestopalov, Yury, 1953-, et al.
(author)
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Development of Numerical Techniques for Forward and Inverse Waveguide Scattering Problems
- 2018
-
In: 2018 2ND URSI Atlantic Radio Science Meeting (AT-RASC). - : IEEE. - 9789082598735
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Conference paper (peer-reviewed)abstract
- Development of the methods and algorithms [1, 2] are considered for the numerical solution to the forward problem of the electromagnetic wave scattering by inhomogeneous dielectric inclusions in a waveguide of rectangular cross section and inverse problem of reconstructing parameters of the dielectric inclusions from the values of the transmission coefficient of the scattered electromagnetic wave. The codes are developed implementing an FDTD method that employs the PML-layer technique. Numerical modeling and simulations are performed for the analysis of the wave propagation in waveguides of rectangular cross section loaded with parallel-plane layered media (layered dielectric diaphragms) and such diaphragms containing cubic dielectric inclusions. Validation is carried out of the results of calculations using closed-form solution [3] to the canonical single-layer structure.Progress in analytical - numerical investigations of the solutions to the forward and inverse waveguide problems are largely based on a recent discovery [4] of the singularities and extrema in the complex domain of the transmission coefficient of layered dielectric diaphragms. In fact, the knowledge of the location of singularity and extrema sets of the scattering matrix allows one to justify correct determination of real or complex permittivity of each layer of the diaphragm by specifying domains in the complex plane where the transmission coefficientis one-to-one; that is, the domains that do not contain singularities and where unique permittivity reconstruction is therefore possible. Forthe forward problem of the scattering of a normal waveguide mode by a single-and three-layer diaphragms with a dielectric cube, it is shown [1, 2] that variation in the values of the transmission coefficient can be up to two orders of magnitude less than that of the permittivity of the inclusion. Taking into account this result and the presence of singularities, improvements are proposed of the numerical method, algorithms and codes implementing the calculations. The results of modeling and computations are validated by comparing with experimental and measurement data [3]. The requirements are formulated that should be imposed on the accuracy of computations and measurements necessary to reconstruct numerically permittivity of the inclusion from the amplitude and phase of the transmitted wave with the prescribed accuracy.1. E. Sheina, A. Smirnov,Y. Shestopalov,and M.Ufimtsev,“FDTD solution of reconstructing permittivity of a dielectric inclusion in a waveguide taking into account measurement inaccuracy,”Progress in Electromagnetics Research Symposium (PIERS),St Petersburg, Russia, 2017, pp. 3188-3195, doi:10.1109/PIERS.2017.8262306.2.E. Sheina, A. Smirnov, and Y. Shestopalov, “Influence of standing waves on the solution of the inverse problem ofreconstructing parameters of a dielectric inclusion in a waveguide,”URSI Int. Symposium on Electromagnetic Theory (EMTS), Espoo, Finland, 2016,pp. 643-646, doi:10.1109/URSI-EMTS.2016.7571479.3. Yu. G. Smirnov, Yu. V. Shestopalov, and E. D. Derevyanchuk, “Inverse problem method for complex permittivity reconstruction of layered media in a rectangular waveguide,”Physica Status Solidi(C), 11,5-6, 2014,pp. 969–974, doi:10.1002/pssc.201300697.4. Y. Shestopalov, “Resonant states in waveguide transmission problems,”PIER B,64: pp.119-143, 2015, doi: 10.2528/PIERB15083001.
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| 9. |
- Shestopalov, Yury, 1953-, et al.
(author)
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On Recent Findings in the Theory of Complex Waves in Open Metal-Dielectric Waveguides
- 2018
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In: 2018 2ND URSI Atlantic Radio Science Meeting (AT-RASC). - : IEEE. - 9789082598735
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Conference paper (peer-reviewed)abstract
- Theory of complex waves (see e.g. [1] and references therein) accumulated a big volume of results. However, its biggest drawback remains which brakes significantly the development of the theory: absence of rigorous proofs of the existence of complex waves. In this respect, studies of complex waves in open metal-dielectric waveguides has been essentially enhanced when two new families of symmetric (angle-independent) complex waves have been identified [2, 3] in a dielectric rod (DR) and Goubau line (GL) with homogeneous dielectric cover: surface complex waves occurring as perturbations of real surface waves caused by the presence of lossy dielectric, and pure complex waves which have no counterpart in the set of real waves. Existence of the latter family of complex waves has been shown using a special technique and the proof [3] of the existence of an infinite set of complex roots of the dispersion equation (DE) describing waves in DR and GL.In this work, a development of the analytical and numerical methods [2, 3] are considered for the analysis of the electromagnetic wave propagation in metal-dielectric waveguides with multi-layered dielectric filling. The first step constitutes extension of the results obtained for symmetric complex waves in DR and GLto the case of non-symmetric (angle-dependent) waves, and the second step, to multi-layered dielectric covers. Both steps are accomplished using specific forms of DEs obtained in [3]by construction analytical continuation of the functions involved in DEs to multi-sheet Riemann surfaces of the spectral parameter and applying appropriate generalization the techniques [4]forfinding complex roots of the DEs.Calculation ofnon-symmetric complex waves employs numerical solution of the DEs with the help of parameter differentiation in the complex domain using multi-parameter setting and analysis of implicit functions of several complex variables [5] and reduction [2, 3] to numerical solution of auxiliary Cauchy problems.1. A. S. Raevskiiand S. B. Raevskii, Complex Waves, Radiotekhnika, Moscow, 2010.2. E. Kuzmina and Y. Shestopalov, “Waves in a lossyGoubau line,”10th European Conf. on Antennas and Propagation (EuCAP), Davos, Switzerland, 2016, doi: 10.1109/EuCAP.2016.7481368.3. E. Kuzmina and Y. Shestopalov, “Complex waves in a dielectric rod and Goubau line,” 19th Int. Conf. on Electromagneticsin Advanced Applications (ICEAA), Verona, Italy, 2017, pp. 963-966, doi: 10.1109/ICEAA.2017.8065417.4. Y. Shestopalov, “Resonant states in waveguide transmission problems,”PIER B,64: pp.119-143, 2015, doi: 10.2528/PIERB15083001.5.Y. Shestopalov,“On unique solvability of multi-parameter waveguide inverse problems, ”19th Int. Conf. on Electromagnetics in Advanced Applications (ICEAA), Verona, Italy, 2017, pp. 372-376, doi: 10.1109/ICEAA.2017.8065253.
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| 10. |
- Vierinen, J., et al.
(author)
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Space debris observation potential with EISCAT 3D
- 2018
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In: 2ND URSI ATLANTIC RADIO SCIENCE MEETING (AT-RASC). - : IEEE. - 9789082598735
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Conference paper (peer-reviewed)abstract
- We investigate the capabilities of the next generation ionospheric research radar EISCAT 3D (E3D) for space debris observations. We have used the current projected design of E3D as basis of this study. To model the performance of E3D for space debris observations, we have included basic radar equation based error analysis for range and range-rate observations. Because the radar will be multi-static, it is also capable of observing instantaneous three-dimensional vector velocities and positions by observing round-trip range and range-rate between the transmitter and three receiver sites. We have included error estimates for both of the the three-dimensional position and three-dimensional vector velocity observations. To estimate the fraction of total debris that can be observed with E3D, we have used the MASTER model. We have also investigated effects of radio wave propagation. E3D uses a relatively low VHF frequency (233 MHz), which experiences more radio wave propagation effects than more conventional higher frequency space surveillance radars. Our modeling shows that ionospheric ray-bending and group delay are severe enough that these effects need to be modeled in order to determine accurate orbital elements. As EISCAT 3D is an ionospheric research radar, there will be high quality ionospheric electron density measurements that can be utilized for radio propagation modeling.
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