نتایج جستجو برای: multifrequency antenna

تعداد نتایج: 46838  

Journal: :International Astronomical Union Colloquium 1988

Journal: :The Astrophysical Journal 1984

Journal: :Monthly Notices of the Royal Astronomical Society 2008

In this paper a new low profile Substrate Integrated Waveguide (SIW) probe-fed H-plane horn antenna structure with improved gain is proposed. The proposed antenna consists of two waveguides including a rectangular and a taper one, in which both, first and third modes of the structure are simultaneously excited leading to a uniform field distribution along the radiating aperture of the antenna a...

Hamed noroozy, Shahrokh Jam,

In this article an Archimedean spiral antenna is designed and analyzed that has good operation in broadband application. By analyzing this design, the effects that different parameters have on antenna operation will be studied and ways of optimization will be found.  Influences of cavity height and number of turns to obtain good matching and gain in a frequency interval of 4 to 18 GHz will be d...

A new four elements compact antenna array is presented and discussed to achieve enhanced phase resolution without sacrificing the array output power. This structure inspired by the Ormia Ochracea’s coupled ears. The analogy between this insect acute directional hearing capabilities and the electrically compact antenna array is used to enhance the array sensitivity to direction of arrival estima...

2008
H. Anderhub L. A. Antonelli P. Antoranz M. Backes C. Baixeras S. Balestra J. A. Barrio H. Bartko D. Bastieri J. Becerra González J. K. Becker C. C. Hsu S. Huber M. Mariotti M. Martínez D. Mazin M. Meucci M. Meyer J. M. Miranda R. Mirzoyan R. Paoletti J. M. Paredes M. Pasanen D. Pascoli F. Pauss R. G. Pegna M. A. Perez-Torres M. Persic L. Peruzzo F. Prada E. Prandini N. Puchades D. F. Torres N. Turini H. Vankov A. Venturini V. Vitale R. M. Wagner

Aims. We report upper limits to the very high energy flux (E > 100 GeV) of the flat spectrum radio quasar 3C 454.3 (z = 0.859) derived by the Cherenkov telescope MAGIC during the high states of July/August and November/December 2007. We compare the upper limits derived in both time slots with the available quasi-simultaneous MeV-GeV data from the AGILE γ-ray satellite and interpret the observat...

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