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Efficient Numerical Investigation of an Active Reconfigurable Periodic Structure

M.Bercigli, R.Guidi, L.Matekovits

Abstract: Application of an advanced numerical scheme, namely the Synthetic Function eXpansion (SFX) algorithm, to the analysis of an active 1D structure is presented. A passive periodic configuration consisting of parallel patches loading a microstrip line is turned into an active structure by inserting a pair of 2 switches to the two ends of each patch; the states of the pair of switches are changed contemporaneously. Variation of the states of the switches modifies the current distribution on the structure. The characterization of the large number of possible configurations requires a huge numerical effort which is alleviate by the use of the proposed method. Examples of the numerical investigations in a case of a 120 element array controlled by different periodic patterns are considered and discussed.

Published on European Conference on Antennas & Propagation (EuCAP2012)

Array Full-Wave Optimization and Space Mapping Techniques Using Fast MoM Solvers

F.Milani, M.Bercigli, M.Bandinelli, A.Freni, G.Vecchi, M.Sabbadini

Abstract: Full-wave optimisation of large arrays is computationally intensive problem even with the most advanced solvers. The paper presents a procedure for the full-wave optimisation of arrays based on a space mapping (SM) procedure. The approach combines the efficiency of MoM-based accelerated modelling techniques with physics-based coarse models to reach unprecedented efficiency in terms of accuracy and computational requirements, while maintaining complete compatibility with common engineering practices.

Published on European Conference on Antennas & Propagation (EuCAP2011)

Efficient Numerical Analysis of Large Planar High Impedance Surface by the Synthetic Function Expansion Technique

L.Matekovits, G.Vecchi, M.Bercigli, M.Bandinelli

Abstract: Application is presented of the Synthetic Function eXpansion (SFX) method to the accurate analysis of devices that incorporate microstrip-technology electromagnetic band-gap structures of large but finite size. The strong reduction of the dimension of the system matrix achieved employing the SFX technique reduces the solution time and the memory occupation, making it possible to analyze large structures on standard computational hardware. Experimental verification confirms the validity of the approach

Published on Microwave and Optical Technology Letters, Vol. 51, N. 11, November 2009


Synthetic-Functions Analysis of Large Aperture-Coupled Antennas

L.Matekovits, G.Vecchi, M.Bercigli, M.Bandinelli

Abstract: The application is described the synthetic function expansion (SFX) approach to large arrays of aperture-coupled antennas. The problem is formulated in terms of coupled magnetic-field continuity integral equations (MFCIE) and electric field integral equations (EFIE), and discretized via the method of moments (MoM). The SFX is a domain-decomposition technique; on each block of the broken-down structure, functions are generated with domain over the entire block. These synthetic functions (SF) are obtained from the solution of the electromagnetic problem for the isolated block upon specification of appropriate sources on the block bounding box, and from a further singular value decomposition (SVD)-based procedure to select the relevant terms. The complete problem is solved using the SFs as basis functions for the MoM. This results in a strong reduction of the MoM matrix size. Applications are presented to configurations of open and cavity-backed radiators.

Published on IEEE Transaction on Antennas and Propagation, Vol. 57, N. 7, July 2009


Dual polarised Multi-Layer Antenna with Complex Feeding Network

A.Giacomini, L.J.Foged, J.M.Baracco, M.Bandinelli, M.Sabbadini

Abstract: Medium gain antennas, in dual polarisation, with high polarisation purity and return loss, operating over a total bandwidth of 30% or more, are needed for numerous applications in the space and ground segments. Such requirements can be satisfied with a novel antenna solutions in multi-layer composite technology as described in previous publications. The antenna consists of a suitable arrangement of layered elements acting as a 3D wave-guiding structure excited by a single or dual polarised patch element. The wave-guiding structure provides the beam focusing and the free space impedance matching of the radiated energy over a large bandwidth. The main advantage of this antenna element is the flexibility to match the overall design to a wide range of stand-alone and array configuration requirements, due to the natural separation of the antenna components responsible for the matching and gain performance. This particular characteristic enables the implementation of a very effective design procedure starting from the initial sizing and preliminary performance estimate up to the final optimization of the antenna performance. The multi-layer structure and the balanced excitation of the feeding section require an accurate numerical modelling for the initial sizing, overall optimisation and feeding network design. Modular breadboards, conducted and radiated measurements and numerical modelling refinements have been used extensively in the development of the antenna element. This paper describes the electrical and mechanical design considerations, manufacturing activity and discuss the final testing of the antenna.

Published on European Conference on Antennas & Propagation (EuCAP2009)


Fast and Accurate Modeling of Quasi-Period Layered Structures

M.Sabbadini, M.Bercigli, M.Bandinelli, A.Freni, P.De Vita

Abstract: Quasi-periodic structures are common in antenna design. Many structures composed by conductive islands on or in layered dielectric share this characteristic, for instance medium and large arrays arranged on semi-regular grids, artificial lenses, reflect-arrays, small polarisation grids and frequency selective surfaces as well as artificial magnetic conductors. Within the EAML development an effort has been made to improve the performance of available full-wave algorithms to cope with the typically very large size of these objects, without compromising on accuracy while keeping computational cost as low as possible. Attention has been focused on both the cost of computing currents on the metallic parts by means of the Method of Moment and on the cost of computing the field radiated by the currents

Published on 30th ESA ANTENNA WORKSHOP, Noordwijk, The Netherland, 27-30 May, 2008

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Acceleration of Full-Wave Algorithms for Design of Multi-Layer Printed Array

M.Sabbadini, M.Bandinelli, A.Freni, S.Maci, G.Vecchi, L.Matekovits, M.Bercigli

Abstract: Multi-layer array design is dominated by the computational cost of the radiated fields using full-wave methods. Among others the EAML activity includes new developments directed to reduce this computational cost by means of various acceleration techniques, generally based on the rearrangement of the solution matrix following the physical characteristics of the array. The use of these techniques allows a reduction of the calculation time by a two or three order of magnitude, thereby allowing the optimisation only of the array excitations but also of the array layout and element design. Furthermore the availability of several acceleration methods within a same tool offers the opportunity to select the most suitable combination for the particular array at hand.

Published on 30th ESA ANTENNA WORKSHOP, Noordwijk, The Netherland, 27-30 May, 2008

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Tools for the Direct Synthesis of Aperture Distributions and Arrays

M.Bercigli, M.Bandinelli, J.L.Araque, G.Vecchi, F.M.Sabbadini

Abstract: Aperture distribution and array synthesis methods have received a vast attention in the literature. Despite this, little is available for the direct synthesis with constrains, e.g. on the maximum allowable amplitude variation across the aperture as integrated into a tool that also allows an effective virtual prototyping. A dedicated research effort within the EAML activity has lead to the availability of a synthesis tool dedicated to this specific problem. In combination with the available full-wave optimisation capabilities and sensitivity analysis features it offers a very effective mean for array design. Both power and field synthesis can be performed, on 1D and 2D performance masks, with a variety of constraints on the aperture. The synthesis tool is seamlessly integrated into virtual prototyping based on full-wave solutions, and into an array-setup interface for the user.

Published on 30th ESA ANTENNA WORKSHOP, Noordwijk, The Netherland, 27-30 May, 2008

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Synthetic-Functions Analysis of Antennas with Slots and Apertures

M.Bercigli, L.Matekovits, G.Vecchi, M.Bandinelli

Abstract: Application of the synthetic function expansion (SFX) approach for the case of aperture coupled structures is investigated. Problems involving slots or apertures into an infinite metal plane are formulated in terms of the magnetic-field continuity equation (MFCIE) for the unknown magnetic currents, typically in association with an electric field integral equation (EFIE) (e.g. for slot-coupled patch antennas). The MCFIE satisfies the requirements that allow a direct application of the SFX constructs, but its detailed formulation and implementation have not been addressed yet.

Published on European Conference on Antennas & Propagation (EuCAP2007)

Efficient Dual-Band Planar Array Suitable to Galileo

M.Bandinelli, R.Guidi, P.Valle, A.Netti, M.Zolesi, R.Mizzoni

Abstract: An optimum dual band self-diplexed antenna, particularly suitable to accomplish the demanding requirements of the European Navigation System (GALILEO) is highlighted. The antenna relies on the key enabling technologies previously developed for the pioneering GIOVE-A satellite (Galileo In Orbit Validation Element) successfully flown on 28 December 2005. Its excellent operational status and the quality of transmitted signal are a validation of the technology solutions adopted to the antenna. Both GIOVE-A and the enhanced design will be described, in particular the solutions adopted to improve the overall performance Vs Galileo.

Published on European Conference on Antennas & Propagation (EuCAP2006)