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B. R. Anuradha - One of the best experts on this subject based on the ideXlab platform.

  • Tri-band MIMO Antenna for WLAN, WiMAX and Defence System & Radio Astronomy Applications
    Applied and Environmental Microbiology, 2018
    Co-Authors: K. B. V. Babu, B. R. Anuradha
    Abstract:

    In this paper, an efficacious and impermeable undeviating MIMO consist of 70 x 50 x 0.4 mm3 is used for WLAN, defence system & Radio Astronomy and WiMAX applications. To keep in order abandoning the reactive connection between the antennas, a neutralizing line is connected between the two symmetrical radiating elements. Another technique to reducing isolation (mutual coupling) between the antennas, four small slits of small size are etched onto to the ground plane. This has resulted in the proposed antenna giving a good bandwidth at the three resonant frequencies of (3.2–3.7 GHz) for Wireless LAN, (5.1–5.6 GHz) WiMAX and (6.7–7.5 GHz) defence system & Radio Astronomy applications with |S11|< -10 dB and mutual coupling |S12|< -20 dB for the entire operating band. The simulation results and measured results demonstrate that tri-band MIMO antenna is more acceptable for the design in portable device applications.

  • tri band mimo antenna for wlan wimax and defence system Radio Astronomy applications
    Applied and Environmental Microbiology, 2018
    Co-Authors: K. B. V. Babu, B. R. Anuradha
    Abstract:

    In this paper, an efficacious and impermeable undeviating MIMO consist of 70 x 50 x 0.4 mm3 is used for WLAN, defence system & Radio Astronomy and WiMAX applications. To keep in order abandoning the reactive connection between the antennas, a neutralizing line is connected between the two symmetrical radiating elements. Another technique to reducing isolation (mutual coupling) between the antennas, four small slits of small size are etched onto to the ground plane. This has resulted in the proposed antenna giving a good bandwidth at the three resonant frequencies of (3.2–3.7 GHz) for Wireless LAN, (5.1–5.6 GHz) WiMAX and (6.7–7.5 GHz) defence system & Radio Astronomy applications with |S11|< -10 dB and mutual coupling |S12|< -20 dB for the entire operating band. The simulation results and measured results demonstrate that tri-band MIMO antenna is more acceptable for the design in portable device applications.

Jill Rathborne - One of the best experts on this subject based on the ideXlab platform.

  • molecular clouds and clumps in the boston university five college Radio Astronomy observatory galactic ring survey
    Astrophysical Journal Supplement Series, 2009
    Co-Authors: James M. Jackson, Jill Rathborne, R. Y. Shah, A. M. Johnson, Robert Simon
    Abstract:

    The Boston University-Five College Radio Astronomy Observatory (BU-FCRAO) Galactic Ring Survey (GRS) of 13CO J = 1 → 0 emission covers Galactic longitudes 18° < l < 557 and Galactic latitudes |b| ≤ 1°. Using the SEQUOIA array on the FCRAO 14 m telescope, the GRS fully sampled the 13CO Galactic emission (46'' angular resolution on a 22'' grid) and achieved a spectral resolution of 0.21 km s–1. Because the GRS uses 13CO, an optically thin tracer, rather than 12CO, an optically thick tracer, the GRS allows a much better determination of column density and also a cleaner separation of velocity components along a line of sight. With this homogeneous, fully sampled survey of 13CO emission, we have identified 829 molecular clouds and 6124 clumps throughout the inner Galaxy using the CLUMPFIND algorithm. Here we present details of the catalog and a preliminary analysis of the properties of the molecular clouds and their clumps. Moreover, we compare clouds inside and outside of the 5 kpc ring and find that clouds within the ring typically have warmer temperatures, higher column densities, larger areas, and more clumps compared with clouds located outside the ring. This is expected if these clouds are actively forming stars. This catalog provides a useful tool for the study of molecular clouds and their embedded young stellar objects.

  • molecular clouds and clumps in the boston university five college Radio Astronomy observatory galactic ring survey
    arXiv: Solar and Stellar Astrophysics, 2009
    Co-Authors: James M. Jackson, Jill Rathborne, R. Y. Shah, A. M. Johnson, Robert Simon
    Abstract:

    The Boston University-Five College Radio Astronomy Observatory (BU-FCRAO) Galactic Ring Survey (GRS) of 13 CO (1-0) emission covers Galactic longitudes 18 deg < l < 55.7 deg and Galactic latitudes |b| <= 1 deg. Using the SEQUOIA array on the FCRAO 14m telescope, the GRS fully sampled the 13 CO Galactic emission (46 arcsec angular resolution on a 22 arcsec grid) and achieved a spectral resolution of 0.21 km/s. Because the GRS uses 13 CO, an optically thin tracer, rather than 12 CO, an optically thick tracer, the GRS allows a much better determination of column density and also a cleaner separation of velocity components along a line of sight. With this homogeneous, fully-sampled survey of 13 CO, emission, we have identified 829 molecular clouds and 6124 clumps throughout the inner Galaxy using the CLUMPFIND algorithm. Here we present details of the catalog and a preliminary analysis of the properties of the molecular clouds and their clumps. Moreover, we compare clouds inside and outside of the 5 kpc ring and find that clouds within the ring typically have warmer temperatures, higher column densities, larger areas, and more clumps compared to clouds located outside the ring. This is expected if these clouds are actively forming stars. This catalog provides a useful tool for the study of molecular clouds and their embedded young stellar objects.

  • the boston university five college Radio Astronomy observatory galactic ring survey
    arXiv: Astrophysics, 2006
    Co-Authors: James M. Jackson, Jill Rathborne, R. Y. Shah, Robert Simon, Thomas M. Bania, Dan P. Clemens, A. M. Johnson, Edward Chambers, M. Dormody
    Abstract:

    The Boston University-Five College Radio Astronomy Observatory Galactic Ring Survey is a new survey of Galactic 13CO (1-0) emission. The survey used the SEQUOIA multi pixel array on the Five College Radio Astronomy Observatory 14 m telescope to cover a longitude range of l = 18 deg-55.7 deg and a latitude range of |b| 40 deg. At the velocity resolution of 0.21 km/s, the typical rms sensitivity is sigma(TA*)~0.13 K. The survey comprises a total of 1,993,522 spectra. We show integrated intensity images (zeroth moment maps), channel maps, position-velocity diagrams, and an average spectrum of the completed survey dataset. We also discuss the telescope and instrumental parameters, the observing modes, the data reduction processes, and the emission and noise characteristics of the dataset. The Galactic Ring Survey data are available to the community at www.bu.edu/galacticring or in DVD form by request.

  • The Boston University-Five College Radio Astronomy Observatory Galactic Ring Survey
    The Astrophysical Journal Supplement Series, 2006
    Co-Authors: James M. Jackson, Jill Rathborne, R. Y. Shah, Robert Simon, Thomas M. Bania, Dan P. Clemens, E. T. Chambers, A. M. Johnson, M. Dormody, R. Lavoie
    Abstract:

    The Boston University-Five College Radio Astronomy Observatory Galactic Ring Survey is a new survey of Galactic 13CO J = 1 → 0 emission. The survey used the SEQUOIA multipixel array on the Five College Radio Astronomy Observatory 14 m telescope to cover a longitude range of l = 18°-557 and a latitude range of |b| 40°. At the velocity resolution of 0.21 km s-1, the typical rms sensitivity is σ(T) ~ 0.13 K. The survey comprises a total of 1,993,522 spectra. We show integrated intensity images (zeroth moment maps), channel maps, position-velocity diagrams, and an average spectrum of the completed survey data set. We also discuss the telescope and instrumental parameters, the observing modes, the data reduction processes, and the emission and noise characteristics of the data set. The Galactic Ring Survey data are available to the community online or in DVD form by request.

Robert Simon - One of the best experts on this subject based on the ideXlab platform.

  • molecular clouds and clumps in the boston university five college Radio Astronomy observatory galactic ring survey
    Astrophysical Journal Supplement Series, 2009
    Co-Authors: James M. Jackson, Jill Rathborne, R. Y. Shah, A. M. Johnson, Robert Simon
    Abstract:

    The Boston University-Five College Radio Astronomy Observatory (BU-FCRAO) Galactic Ring Survey (GRS) of 13CO J = 1 → 0 emission covers Galactic longitudes 18° < l < 557 and Galactic latitudes |b| ≤ 1°. Using the SEQUOIA array on the FCRAO 14 m telescope, the GRS fully sampled the 13CO Galactic emission (46'' angular resolution on a 22'' grid) and achieved a spectral resolution of 0.21 km s–1. Because the GRS uses 13CO, an optically thin tracer, rather than 12CO, an optically thick tracer, the GRS allows a much better determination of column density and also a cleaner separation of velocity components along a line of sight. With this homogeneous, fully sampled survey of 13CO emission, we have identified 829 molecular clouds and 6124 clumps throughout the inner Galaxy using the CLUMPFIND algorithm. Here we present details of the catalog and a preliminary analysis of the properties of the molecular clouds and their clumps. Moreover, we compare clouds inside and outside of the 5 kpc ring and find that clouds within the ring typically have warmer temperatures, higher column densities, larger areas, and more clumps compared with clouds located outside the ring. This is expected if these clouds are actively forming stars. This catalog provides a useful tool for the study of molecular clouds and their embedded young stellar objects.

  • molecular clouds and clumps in the boston university five college Radio Astronomy observatory galactic ring survey
    arXiv: Solar and Stellar Astrophysics, 2009
    Co-Authors: James M. Jackson, Jill Rathborne, R. Y. Shah, A. M. Johnson, Robert Simon
    Abstract:

    The Boston University-Five College Radio Astronomy Observatory (BU-FCRAO) Galactic Ring Survey (GRS) of 13 CO (1-0) emission covers Galactic longitudes 18 deg < l < 55.7 deg and Galactic latitudes |b| <= 1 deg. Using the SEQUOIA array on the FCRAO 14m telescope, the GRS fully sampled the 13 CO Galactic emission (46 arcsec angular resolution on a 22 arcsec grid) and achieved a spectral resolution of 0.21 km/s. Because the GRS uses 13 CO, an optically thin tracer, rather than 12 CO, an optically thick tracer, the GRS allows a much better determination of column density and also a cleaner separation of velocity components along a line of sight. With this homogeneous, fully-sampled survey of 13 CO, emission, we have identified 829 molecular clouds and 6124 clumps throughout the inner Galaxy using the CLUMPFIND algorithm. Here we present details of the catalog and a preliminary analysis of the properties of the molecular clouds and their clumps. Moreover, we compare clouds inside and outside of the 5 kpc ring and find that clouds within the ring typically have warmer temperatures, higher column densities, larger areas, and more clumps compared to clouds located outside the ring. This is expected if these clouds are actively forming stars. This catalog provides a useful tool for the study of molecular clouds and their embedded young stellar objects.

  • the boston university five college Radio Astronomy observatory galactic ring survey
    arXiv: Astrophysics, 2006
    Co-Authors: James M. Jackson, Jill Rathborne, R. Y. Shah, Robert Simon, Thomas M. Bania, Dan P. Clemens, A. M. Johnson, Edward Chambers, M. Dormody
    Abstract:

    The Boston University-Five College Radio Astronomy Observatory Galactic Ring Survey is a new survey of Galactic 13CO (1-0) emission. The survey used the SEQUOIA multi pixel array on the Five College Radio Astronomy Observatory 14 m telescope to cover a longitude range of l = 18 deg-55.7 deg and a latitude range of |b| 40 deg. At the velocity resolution of 0.21 km/s, the typical rms sensitivity is sigma(TA*)~0.13 K. The survey comprises a total of 1,993,522 spectra. We show integrated intensity images (zeroth moment maps), channel maps, position-velocity diagrams, and an average spectrum of the completed survey dataset. We also discuss the telescope and instrumental parameters, the observing modes, the data reduction processes, and the emission and noise characteristics of the dataset. The Galactic Ring Survey data are available to the community at www.bu.edu/galacticring or in DVD form by request.

  • The Boston University-Five College Radio Astronomy Observatory Galactic Ring Survey
    The Astrophysical Journal Supplement Series, 2006
    Co-Authors: James M. Jackson, Jill Rathborne, R. Y. Shah, Robert Simon, Thomas M. Bania, Dan P. Clemens, E. T. Chambers, A. M. Johnson, M. Dormody, R. Lavoie
    Abstract:

    The Boston University-Five College Radio Astronomy Observatory Galactic Ring Survey is a new survey of Galactic 13CO J = 1 → 0 emission. The survey used the SEQUOIA multipixel array on the Five College Radio Astronomy Observatory 14 m telescope to cover a longitude range of l = 18°-557 and a latitude range of |b| 40°. At the velocity resolution of 0.21 km s-1, the typical rms sensitivity is σ(T) ~ 0.13 K. The survey comprises a total of 1,993,522 spectra. We show integrated intensity images (zeroth moment maps), channel maps, position-velocity diagrams, and an average spectrum of the completed survey data set. We also discuss the telescope and instrumental parameters, the observing modes, the data reduction processes, and the emission and noise characteristics of the data set. The Galactic Ring Survey data are available to the community online or in DVD form by request.

K. B. V. Babu - One of the best experts on this subject based on the ideXlab platform.

  • Tri-band MIMO Antenna for WLAN, WiMAX and Defence System & Radio Astronomy Applications
    Applied and Environmental Microbiology, 2018
    Co-Authors: K. B. V. Babu, B. R. Anuradha
    Abstract:

    In this paper, an efficacious and impermeable undeviating MIMO consist of 70 x 50 x 0.4 mm3 is used for WLAN, defence system & Radio Astronomy and WiMAX applications. To keep in order abandoning the reactive connection between the antennas, a neutralizing line is connected between the two symmetrical radiating elements. Another technique to reducing isolation (mutual coupling) between the antennas, four small slits of small size are etched onto to the ground plane. This has resulted in the proposed antenna giving a good bandwidth at the three resonant frequencies of (3.2–3.7 GHz) for Wireless LAN, (5.1–5.6 GHz) WiMAX and (6.7–7.5 GHz) defence system & Radio Astronomy applications with |S11|< -10 dB and mutual coupling |S12|< -20 dB for the entire operating band. The simulation results and measured results demonstrate that tri-band MIMO antenna is more acceptable for the design in portable device applications.

  • tri band mimo antenna for wlan wimax and defence system Radio Astronomy applications
    Applied and Environmental Microbiology, 2018
    Co-Authors: K. B. V. Babu, B. R. Anuradha
    Abstract:

    In this paper, an efficacious and impermeable undeviating MIMO consist of 70 x 50 x 0.4 mm3 is used for WLAN, defence system & Radio Astronomy and WiMAX applications. To keep in order abandoning the reactive connection between the antennas, a neutralizing line is connected between the two symmetrical radiating elements. Another technique to reducing isolation (mutual coupling) between the antennas, four small slits of small size are etched onto to the ground plane. This has resulted in the proposed antenna giving a good bandwidth at the three resonant frequencies of (3.2–3.7 GHz) for Wireless LAN, (5.1–5.6 GHz) WiMAX and (6.7–7.5 GHz) defence system & Radio Astronomy applications with |S11|< -10 dB and mutual coupling |S12|< -20 dB for the entire operating band. The simulation results and measured results demonstrate that tri-band MIMO antenna is more acceptable for the design in portable device applications.

G Woan - One of the best experts on this subject based on the ideXlab platform.

  • a generalized measurement equation and van cittert zernike theorem for wide field Radio astronomical interferometry
    Monthly Notices of the Royal Astronomical Society, 2009
    Co-Authors: T D Carozzi, G Woan
    Abstract:

    We derive a generalized van Cittert-Zernike (vC-Z) theorem for Radio Astronomy that is valid for partially polarized sources over an arbitrarily wide field of view (FoV). The classical vC-Z theorem is the theoretical foundation of Radio astronomical interferometry, and its application is the basis of interferometric imaging. Existing generalized vC-Z theorems in Radio Astronomy assume, however, either paraxiality (narrow FoV) or scalar (unpolarized) sources. Our theorem uses neither of these assumptions, which are seldom fulfiled in practice in Radio Astronomy, and treats the full electromagnetic field. To handle wide, partially polarized fields, we extend the two-dimensional (2D) electric field (Jones vector) formalism of the standard ‘Measurement Equation’ (ME) of Radio astronomical interferometry to the full three-dimensional (3D) formalism developed in optical coherence theory. The resulting vC-Z theorem enables full-sky imaging in a single telescope pointing, and imaging based not only on standard dual-polarized interferometers (that measure 2D electric fields) but also electric tripoles and electromagnetic vector-sensor interferometers. We show that the standard 2D ME is easily obtained from our formalism in the case of dual-polarized antenna element interferometers. We also exploit an extended 2D ME to determine that dual-polarized interferometers can have polarimetric aberrations at the edges of a wide FoV. Our vC-Z theorem is particularly relevant to proposed, and recently developed, wide FoV interferometers such as Low Frequency Array (LOFAR) and Square Kilometer Array (SKA), for which direction-dependent effects will be important.

  • a generalised measurement equation and van cittert zernike theorem for wide field Radio astronomical interferometry
    arXiv: Astrophysics, 2008
    Co-Authors: T D Carozzi, G Woan
    Abstract:

    We derive a generalised van Cittert-Zernike (vC-Z) theorem for Radio Astronomy that is valid for partially polarized sources over an arbitrarily wide field-of-view (FoV). The classical vC-Z theorem is the theoretical foundation of Radio astronomical interferometry, and its application is the basis of interferometric imaging. Existing generalised vC-Z theorems in Radio Astronomy assume, however, either paraxiality (narrow FoV) or scalar (unpolarized) sources. Our theorem uses neither of these assumptions, which are seldom fulfilled in practice in Radio Astronomy, and treats the full electromagnetic field. To handle wide, partially polarized fields, we extend the two-dimensional electric field (Jones vector) formalism of the standard "Measurement Equation" of Radio astronomical interferometry to the full three-dimensional formalism developed in optical coherence theory. The resulting vC-Z theorem enables all-sky imaging in a single telescope pointing, and imaging using not only standard dual-polarized interferometers (that measure 2-D electric fields), but also electric tripoles and electromagnetic vector-sensor interferometers. We show that the standard 2-D Measurement Equation is easily obtained from our formalism in the case of dual-polarized antenna element interferometers. We find, however, that such dual-polarized interferometers can have polarimetric aberrations at the edges of the FoV that are often correctable. Our theorem is particularly relevant to proposed and recently developed wide FoV interferometers such as LOFAR and SKA, for which direction-dependent effects will be important.