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  • Diffraction by a quarterplane of the field from a halfwave dipole | TICRA
    Optimization Physical Optics Reflectarray Reflector antenna Scattering Diffraction by a quarterplane of the field from a halfwave dipole Abstract The scattered far field from a halfwave dipole illuminating a perfectly conducting quarterplane is calculated The calculation is based on a calculation of the radial electric and magnetic field components on the far field sphere using uniform geometrical theory of diffraction GTD and subsequent conversion of the radial fields into transverse

    Original URL path: http://www.ticra.com/papers/diffraction-quarterplane-field-halfwave-dipole (2016-05-01)
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  • The SNFGTD Method and its Accuracy | TICRA
    is computed on a spherical surface enclosing the antenna using the geometrical theory of diffraction The far field is subsequently found by means of a spherical near field to far field transformation based on a spherical wave expansion of the near field Due to the properties of the SNF transformation the total far field may be obtained as a sum of transformed contributions which facilitates analysis of collimated beams It

    Original URL path: http://www.ticra.com/papers/snfgtd-method-and-its-accuracy (2016-05-01)
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  • Shortcomings of cross polarisation methods for reflector antennas | TICRA
    Reflectarray Reflector antenna Scattering Shortcomings of cross polarisation methods for reflector antennas Abstract The still increasing requirements to satellite reflector antennas in particular with respect to such parameters as cross polarisation and side lobe level imply a demand for fast and accurate analysis methods by which the performance of the reflectors can be predicted One such approach is the SNFGTD method Bach et al 1981 in which the near field from the reflector is cal culated on a sphere by using the GTD and transformed into the far field by using a spherical expansion In the near field the advantages of ray optics may be fully exploited since the caustic of reflected rays which in the far field occurs in the main beam direction does not exist close to the antenna For example the ray description allows a rigorous treatment of blockage from feed or subreflector simply by tracing the rays through the system while physical optics PO relies on a truncation of the induced currents in shadowed regions In addition since the near field to far field transformation makes use of the FFT Larsen 1980 SNFGTD will in many cases be superior to PO with respect to computer time

    Original URL path: http://www.ticra.com/papers/shortcomings-cross-polarisation-methods-reflector-antennas (2016-05-01)
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  • Papers tagged with : GTD | TICRA
    Jun 1984 Analysis of subreflectors for dual reflector antennas Authors Niels Christian Albertsen Knud Pontoppidan The paper presents various methods for the calculation of the field reflected from a subreflector in a dual reflector antenna system It is demonstrated that the physical optics PO solution 01 May 1977 Caustics and Caustic Corrections to the Field Diffracted by a Curved Edge Authors Niels Christian Albertsen The caustics for the singly diffracted

    Original URL path: http://www.ticra.com/papers/18?page=1 (2016-05-01)
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  • DTU-ESA Millimeter-Wave Validation Standard Antenna (mm-VAST) – Detailed Design | TICRA
    challenges of integrating an aluminum feed cluster with high thermal expansion coefficient in a CFRP support frame with very low thermal expansion coefficient Abstract A design of a well characterized mechanically and thermally stable multi frequency VAlidation STandard antenna for mm wave frequencies mm VAST developed in an ESA project is presented The antenna will facilitate inter comparison and validation of antenna measurement ranges at K Ka and Q V

    Original URL path: http://www.ticra.com/papers/dtu-esa-millimeter-wave-validation-standard-antenna-mm-vast-detailed-design (2016-05-01)
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  • DTU-ESA Millimeter-Wave Validation Standard Antenna – Requirements and Design | TICRA
    leading to improvements of the measurement accuracy and facilitating better understanding of the measurement techniques The maximum value from a validation campaign is achieved when a dedicated Validation Standard VAST antenna specifically designed for this purpose is available The driving requirements to VAST antennas are their mechanical stability with respect to any orientation of the antenna in the gravity field and thermal stability over a given operational temperature range In addition VAST antennas must possess electrical characteristics that are typical for satellite antennas and challenging to measure A multi band millimeter wave VAST mm VAST antenna for the K Ka bands and Q V bands is currently under development in collaboration between the Technical University of Denmark DTU and TICRA under contract from the European Space Agency In this paper the electrical and mechanical requirements of the DTU ESA mm VAST antenna are discussed and presented Potential antenna types fulfilling the electrical requirements are briefly reviewed and the baseline design is described The emphasis is given to definition of the requirements for the mechanical and thermal stability of the antenna which satisfy the stringent stability requirement for the mm VAST electrical characteristics Publication Proc AMTA 36th Annual Meeting Symposium Place

    Original URL path: http://www.ticra.com/papers/dtu-esa-millimeter-wave-validation-standard-antenna-requirements-and-design (2016-05-01)
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  • Accurate and Efficient Analysis of Printed Reflectarrays With Arbitrary Elements Using Higher-Order Hierarchical Legendre Basis Functions | TICRA
    the edges of the reflectarray elements thus yielding good convergence properties and very accurate results In addition the number of Floquet harmonics needed in the spectral domain method of moments is reduced by using higher order hierarchical Legendre basis functions as compared to singular basis functions At the same time higher order hierarchical Legendre basis functions can be applied to any arbitrarily shaped array elements thus providing the flexibility required

    Original URL path: http://www.ticra.com/papers/accurate-and-efficient-analysis-printed-reflectarrays-arbitrary-elements-using-higher-order (2016-05-01)
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  • Investigations on Accurate Analysis of Microstrip Reflectarrays | TICRA
    in reflectarray analysis are examined and solutions to these issues are proposed The focus is on two sources of error namely the determination of the equivalent currents to calculate the radiation pattern and the inaccurate mutual coupling between array elements due to the lack of periodicity To serve as reference two offset reflectarray antennas have been designed manufactured and measured at the DTUESA Spherical Near Field Antenna Test Facility Comparisons

    Original URL path: http://www.ticra.com/papers/investigations-accurate-analysis-microstrip-reflectarrays (2016-05-01)
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