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ABSTRACT: In this paper, a study of the coupling between a rectangular waveguide and circular waveguide is presented, aimed at developing a design procedure for a rectangular to circular waveguide directional coupler. Since radio-astronomical receivers often exploit circular horns, a coupler sharing the same waveguide type is at a premium, and furthermore, it reduces the feeding network complexity in dual polarization applications. A novel approach for obtaining traveling wave modal amplitude coefficients is presented, suitable for modes of any order. This approach is used to analyze the behavior of a single hole coupler between a rectangular and circular waveguide. From this starting point, a four holes directional coupler with good performance is designed in the 22-GHz band. Measurements and full-wave numerical simulations show excellent agreement with the proposed theory.
IEEE Transactions on Microwave Theory and Techniques 08/2009; · 1.85 Impact Factor
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ABSTRACT: A numerical investigation on mutual coupling between two neighboring DRAs suitable for AIA array applications has been presented. The proposed geometries show that the harmonic tuning governing the mismatch of the radiator at higher harmonics, which is vital for a correct PA loading, remains substantially unchanged.
Antennas and Propagation Society International Symposium, 2008. AP-S 2008. IEEE; 08/2008
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ABSTRACT: In this paper the performances of a crossfeed system was analyzed in presence of stochastic rough sea scattering, whereas in other literature the crossfeeds monopulse have been analyzed only under the hypothesis of flat earth and perfectly smooth sea (Schenkel, 1987). Furthermore the effect of manufacturing tolerances in the passive network backing the antenna was considered. These errors can lead to small phase bias in the different monopulse channels, leading to inaccurate tracking. The different effects of these phase errors on standard and crossfeed monopulse radars were discussed.
Antennas and Propagation Society International Symposium, 2007 IEEE; 07/2007
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ABSTRACT: In this work, the study will be focused on dielectric resonator antennas (DRA). A parametric analysis of the reflection coefficient for a cylindrical slot fed DRA has been presented, with the aim of finding the optimal shape factor to reject the second-order harmonic.
Antennas and Propagation Society International Symposium, 2007 IEEE; 07/2007
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ABSTRACT: A simple and efficient perturbative approach to analyze the electromagnetic coupling among circular horns is proposed in this paper. The method is based on an analysis tool which combines two different techniques: a mode matching (MM) technique for the propagation inside the horn and a method of moments (MoM) technique for the radiation of the horn taking into account the external part of all the horns of the cluster. The resulting linear system is solved via a very simple iterative procedure in which one can easily control the number of additive terms until the convergence is reached. The method can analyze arbitrarily large horn clusters with moderate computer resources. One of the main benefits of the new procedure is that one can exploit programs developed to analyze stand-alone horns also to evaluate the electromagnetic coupling
IEEE Transactions on Antennas and Propagation 02/2007; · 2.15 Impact Factor
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Antennas and Propagation Society International Symposium 2006, IEEE; 08/2006
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ABSTRACT: This paper is aimed at describing a low-cost, compact, nearly omnidirectional antenna working at 4 different frequencies (0.5, 0.9, 1.8 and 2.1 GHz). Several configuration of tunable antennas have been presented in the past, some indeed only on a limited frequency range, by varying lumped loads, some truly reconfigurable antennas, whose geometry is varied by solid state switches, or MEMS up to extremely flexible, and costly, MEMS-based fully reconfigurable planar antennas. Particular care must also be taken in considering the effect of the control lines for the switches, which needs to be shielded, or to be made of non conducting materials, like optical fibers to avoid negative effects on radiation. Since the latter approach is more costly, conventional control lines are used here, and their effect fully considered
Antennas and Propagation Society International Symposium 2006, IEEE; 08/2006
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ABSTRACT: In this paper the electromagnetic coupling between a corrugated horn and a reflector dish is analyzed with a new hybrid perturbative technique. This coupling may produce significant modifications especially in the return loss and in the cross-polar pattern of the feed. The hybrid perturbative approach combines three different techniques: a mode matching (MM) technique for the propagation inside the horn, a method of moments (MoM) technique for the radiation of the horn taking into account the external part of the horn itself, and a fast Gaussian beam asymptotic physical optics (FGBAPO) technique for the interactions between the feed and the reflector. Some measurements and the comparison with rigorous numerical results demonstrate the accuracy of the new hybrid technique and the effects of this electromagnetic coupling on the feed performance.
IEEE Transactions on Antennas and Propagation 03/2006; · 2.15 Impact Factor
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04/2005; , ISBN: 9780471654506
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ABSTRACT: A fast and accurate procedure for the analysis of composite horn-reflector antenna systems with electrically large dimensions is here presented. The horn analysis is carried out exploiting the mode matching (MM) and the combined field-integral equation (CFIE) techniques. For the reflector characterization a PO-based Gaussian beam asymptotic technique is used. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 42: 95–100, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20219
Microwave and Optical Technology Letters 07/2004; 42(2):95 - 100. · 0.62 Impact Factor
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ABSTRACT: Having compact horns with a highly stable phase center reduces efficiency dropping for defocusing at the frequency band extremes. Conventionally, these horns are designed with a square sinus plus exponential profile. We use an extremely flexible mathematical profile, based on non uniform rational B-splines (NURBS), within an automatic genetic algorithm design procedure to achieve better performances.
Antennas and Propagation Society International Symposium, 2003. IEEE; 07/2003
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M ALBANI,
A ARMOGIDA,
F CAPOLINO,
F D'AGOSTINO,
V G DANIELE,
C GENNARELLI,
R D GRAGLIA,
G LOMBARDI, L LUCCI,
S MACI,
G MANARA,
P NEPA,
G PELOSI,
G RICCIO,
S SELLERI,
R TIBERIO,
A TOCCAFONDI,
G TOSO,
ZICH R
ATTI DELLA FONDAZIONE GIORGIO RONCHI. 01/2003; LVIII:393-428.
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ABSTRACT: Compact horns with highly stable phase centre reduce efficiency dropping for defocusing at the frequency band extremes. In this contribution an automatic design procedure for such horns, based on a parallel genetic algorithm, is described. The algorithm operates on many horn profile parameters, including corrugations, and is based on an accurate full-wave mode matching/combined field integral equation analysis code.
Antennas and Propagation Society International Symposium, 2002. IEEE; 02/2002
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ABSTRACT: In this contribution the design of the front-end of the 22-GHz cooled
receiver for the Sardinia Radio Telescope (SRT) is presented. It
comprises a corrugated horn feed, a directional coupler and a polarizer.
A quite original design approach has been adopted since these devices
have been optimized for high performance in the 19-26 GHz-band.
Prototypes of the above components have been produced and tested
highlighting very good agreement with the expected electromagnetic
behaviour. Furthermore, in this contribution the effects of the beam in
the sky due to the above front-end feeding the Gregorian dual-mirror
configuration of the SRT are analyzed.
Memorie della Societa Astronomica Italiana Supplementi. 10:50.
