The aim of this paper is to propose a new simple design of a ultra-wide bandpass filter (3.1 to 1... more The aim of this paper is to propose a new simple design of a ultra-wide bandpass filter (3.1 to 10.6 GHz) based on the cascading of a low pass and a high pass section. They are separately designed using convenient structures leading to compactness and easy fabrication. A stepped impedance structure providing elliptic response has been used for the low
The aim of this paper is to propose a new simple design of a ultra-wide bandpass filter (3.1 to 1... more The aim of this paper is to propose a new simple design of a ultra-wide bandpass filter (3.1 to 10.6 GHz) based on the cascading of a low pass and a high pass section. They are separately designed using convenient structures leading to compactness and easy fabrication. A stepped impedance structure providing elliptic response has been used for the low
Proceedings of the 5th European Conference on Antennas and Propagation, Apr 11, 2011
ABSTRACT This paper presents a multipole expansion for the layered media Green's function... more ABSTRACT This paper presents a multipole expansion for the layered media Green's function (GF). It is obtained thanks to a closed-form expression of the GF as a finite sum of Hankel functions. This multipole expansion can be introduced in the framework of Mixed-Potential Integral Equation (MPIE) formulations and solved with the Method-of-Moments (MoM). Then, when applying the Macro Basis Function (MBF) technique, one can exploit the aforementioned expansion in order to provide a fast evaluation of the reaction integrals between the set of MBFs considered for the array radiating element. Moreover, the size reduction of the MoM system of equations achieved using MBFs, allows one to save resources in terms of memory and solution time.
2013 International Conference on Electromagnetics in Advanced Applications, Sep 1, 2013
ABSTRACT This paper is focused on the analysis of the propagation characteristics of periodic str... more ABSTRACT This paper is focused on the analysis of the propagation characteristics of periodic structures consisting of a host line loaded with split ring resonators (SRRs). It is well known that these structures exhibit stop band functionality in the vicinity of the resonance frequency of the SRRs, and propagation is forward in the transmission bands. However, by enhancing inter-resonators' coupling the forbidden band widens and this enhancement can be interpreted as due to the presence of complex modes. This has been demonstrated through Bloch mode analysis of the multiport equivalent circuit model of the unit cell.
This contribution presents a microstrip implementation of a system exhibiting an electromagnetic ... more This contribution presents a microstrip implementation of a system exhibiting an electromagnetic response that mimics the response of compound diffraction gratings investigated in the optics community. The transmission response of periodic structures of this kind has attracted a lot of attention in the frame of the so called extraordinary transmission phenomena. Recently, some of the authors have developed physical explanations based on standard transmission line and waveguide theory. This paper shows that, conversely, phenomena observed in the optics frame can be replicated with transmission line and circuit analogs. The identification of such analogies are very fruitful for the understanding of the phenomena but also for the development of design strategies to build practical devices based on such phenomena. This paper shows circuit analogs, traditionally used to explain many physical phenomena, providing physical insight and a pedagogical introduction to extraordinary transmission phenomena.
Proceedings of the 5th European Conference on Antennas and Propagation, Apr 11, 2011
In this paper we compare two techniques for the efficient computation of the infinite series that... more In this paper we compare two techniques for the efficient computation of the infinite series that lead to the off- diagonal elements of the vector potential dyadic periodic Green's function in multilayered media. It is shown that the technique based on the combined use of the generalized pencil of functions (GPoF) and Ewald's method is the fastest technique, but is not accurate when the distance between the field point and the sources approaches zero. To avoid this problem, we present a novel technique based on the combined use of the GPoF and the spectral Kummer-Poisson's method, which is only slightly slower than the former technique and turns out to be accurate in the whole range of distances between the field point and the sources. I. INTRODUCTION The analysis of periodic structures in multilayered media is essential to the design of frequency selective surfaces (1), (2) and microwave circuits enclosed by rectangular shields (3), (4). One of the most popular techniques for the electro- magnetic analysis of multilayered periodic structures is the application of the method of moments (MoM) to the solution of mixed potential integral equations (MPIE) (2)-(4). The solution of these integral equations requires the numerical computation of both the scalar potential multilayered periodic Green's functions (SPMPGF) and the vector potential multi- layered periodic dyadic Green's functions (VPMPDGF) in the spatial domain (5). These spatial domain Green's functions can be expressed as double spectral infinite series which are slowly convergent. One of the most efficient approaches for the evaluation of these series is that presented in (6) and (7), where the discrete complex image method (DCIM) is hybridized with Kummer's transformation. So far the hybrid Kummer-DCIM method has been successfully applied to the fast and accurate computation of the SPMPGF and the diagonal elements of the VPMPDGF (6), (7). In this paper, we apply the Kummer- DCIM method to the computation of the off-diagonal elements of the VPMPDGF, and we show that the method provides inaccurate results when the distance between the field point and the sources approaches zero. In order to avoid this inac- curacy problem, we propose a novel method to compute the off-diagonal elements of the VPMPDGF. This novel method is based on Kummer's transformation, and it uses an asymptotic term (8) plus a modified DCIM term in order to obtain accurate asymptotic expressions for the off-diagonal spectral Green's functions. In the novel method the asymptotic series are calculated by means of the spectral Kummer-Poisson's method with asymptotic extraction of higher-order terms (9). The novel method is typically 40% slower than the hybrid Kummer-DCIM, but it turns out to be accurate in the whole range of distances between the field point and the sources.
Ieee Transactions on Antennas and Propagation, Jul 1, 2011
The authors focus on the efficient computation of the slowly convergent infinite series that lead... more The authors focus on the efficient computation of the slowly convergent infinite series that lead to the off-diagonal elements of the vector potential multilayered periodic dyadic Green's function. Two different approaches based on Kummer's transformation are applied to the evaluation of these series. The well-known approach that makes use of the generalized pencil of functions (GPoF) and Ewald's method is
IEEE Transactions on Antennas and Propagation, 2015
ABSTRACT A fully analytical multimodal equivalent circuit is presented for the modeling of the sc... more ABSTRACT A fully analytical multimodal equivalent circuit is presented for the modeling of the scattering of an obliquely incident plane wave by a two-dimensional (2-D) periodic array of metallic patches (or apertures in a metallic screen) embedded in a layered medium. The topology of the equivalent network is rigorously derived in the analysis and all the network parameters are given in closed form. In contrast with the previously reported explicit circuit models, the proposed approach accounts for dynamical effects over a very wide frequency range, which enables the application of the model to a great variety of situations. The key advantages of the reported multimodal network representation are its analytical nature, its extremely low-computational cost and that the physical phenomena involved in the scattering can be easily understood in terms of transmission line and lumped circuital reasonings.
The aim of this paper is to propose a new simple design of a ultra-wide bandpass filter (3.1 to 1... more The aim of this paper is to propose a new simple design of a ultra-wide bandpass filter (3.1 to 10.6 GHz) based on the cascading of a low pass and a high pass section. They are separately designed using convenient structures leading to compactness and easy fabrication. A stepped impedance structure providing elliptic response has been used for the low
The aim of this paper is to propose a new simple design of a ultra-wide bandpass filter (3.1 to 1... more The aim of this paper is to propose a new simple design of a ultra-wide bandpass filter (3.1 to 10.6 GHz) based on the cascading of a low pass and a high pass section. They are separately designed using convenient structures leading to compactness and easy fabrication. A stepped impedance structure providing elliptic response has been used for the low
Proceedings of the 5th European Conference on Antennas and Propagation, Apr 11, 2011
ABSTRACT This paper presents a multipole expansion for the layered media Green's function... more ABSTRACT This paper presents a multipole expansion for the layered media Green's function (GF). It is obtained thanks to a closed-form expression of the GF as a finite sum of Hankel functions. This multipole expansion can be introduced in the framework of Mixed-Potential Integral Equation (MPIE) formulations and solved with the Method-of-Moments (MoM). Then, when applying the Macro Basis Function (MBF) technique, one can exploit the aforementioned expansion in order to provide a fast evaluation of the reaction integrals between the set of MBFs considered for the array radiating element. Moreover, the size reduction of the MoM system of equations achieved using MBFs, allows one to save resources in terms of memory and solution time.
2013 International Conference on Electromagnetics in Advanced Applications, Sep 1, 2013
ABSTRACT This paper is focused on the analysis of the propagation characteristics of periodic str... more ABSTRACT This paper is focused on the analysis of the propagation characteristics of periodic structures consisting of a host line loaded with split ring resonators (SRRs). It is well known that these structures exhibit stop band functionality in the vicinity of the resonance frequency of the SRRs, and propagation is forward in the transmission bands. However, by enhancing inter-resonators' coupling the forbidden band widens and this enhancement can be interpreted as due to the presence of complex modes. This has been demonstrated through Bloch mode analysis of the multiport equivalent circuit model of the unit cell.
This contribution presents a microstrip implementation of a system exhibiting an electromagnetic ... more This contribution presents a microstrip implementation of a system exhibiting an electromagnetic response that mimics the response of compound diffraction gratings investigated in the optics community. The transmission response of periodic structures of this kind has attracted a lot of attention in the frame of the so called extraordinary transmission phenomena. Recently, some of the authors have developed physical explanations based on standard transmission line and waveguide theory. This paper shows that, conversely, phenomena observed in the optics frame can be replicated with transmission line and circuit analogs. The identification of such analogies are very fruitful for the understanding of the phenomena but also for the development of design strategies to build practical devices based on such phenomena. This paper shows circuit analogs, traditionally used to explain many physical phenomena, providing physical insight and a pedagogical introduction to extraordinary transmission phenomena.
Proceedings of the 5th European Conference on Antennas and Propagation, Apr 11, 2011
In this paper we compare two techniques for the efficient computation of the infinite series that... more In this paper we compare two techniques for the efficient computation of the infinite series that lead to the off- diagonal elements of the vector potential dyadic periodic Green's function in multilayered media. It is shown that the technique based on the combined use of the generalized pencil of functions (GPoF) and Ewald's method is the fastest technique, but is not accurate when the distance between the field point and the sources approaches zero. To avoid this problem, we present a novel technique based on the combined use of the GPoF and the spectral Kummer-Poisson's method, which is only slightly slower than the former technique and turns out to be accurate in the whole range of distances between the field point and the sources. I. INTRODUCTION The analysis of periodic structures in multilayered media is essential to the design of frequency selective surfaces (1), (2) and microwave circuits enclosed by rectangular shields (3), (4). One of the most popular techniques for the electro- magnetic analysis of multilayered periodic structures is the application of the method of moments (MoM) to the solution of mixed potential integral equations (MPIE) (2)-(4). The solution of these integral equations requires the numerical computation of both the scalar potential multilayered periodic Green's functions (SPMPGF) and the vector potential multi- layered periodic dyadic Green's functions (VPMPDGF) in the spatial domain (5). These spatial domain Green's functions can be expressed as double spectral infinite series which are slowly convergent. One of the most efficient approaches for the evaluation of these series is that presented in (6) and (7), where the discrete complex image method (DCIM) is hybridized with Kummer's transformation. So far the hybrid Kummer-DCIM method has been successfully applied to the fast and accurate computation of the SPMPGF and the diagonal elements of the VPMPDGF (6), (7). In this paper, we apply the Kummer- DCIM method to the computation of the off-diagonal elements of the VPMPDGF, and we show that the method provides inaccurate results when the distance between the field point and the sources approaches zero. In order to avoid this inac- curacy problem, we propose a novel method to compute the off-diagonal elements of the VPMPDGF. This novel method is based on Kummer's transformation, and it uses an asymptotic term (8) plus a modified DCIM term in order to obtain accurate asymptotic expressions for the off-diagonal spectral Green's functions. In the novel method the asymptotic series are calculated by means of the spectral Kummer-Poisson's method with asymptotic extraction of higher-order terms (9). The novel method is typically 40% slower than the hybrid Kummer-DCIM, but it turns out to be accurate in the whole range of distances between the field point and the sources.
Ieee Transactions on Antennas and Propagation, Jul 1, 2011
The authors focus on the efficient computation of the slowly convergent infinite series that lead... more The authors focus on the efficient computation of the slowly convergent infinite series that lead to the off-diagonal elements of the vector potential multilayered periodic dyadic Green's function. Two different approaches based on Kummer's transformation are applied to the evaluation of these series. The well-known approach that makes use of the generalized pencil of functions (GPoF) and Ewald's method is
IEEE Transactions on Antennas and Propagation, 2015
ABSTRACT A fully analytical multimodal equivalent circuit is presented for the modeling of the sc... more ABSTRACT A fully analytical multimodal equivalent circuit is presented for the modeling of the scattering of an obliquely incident plane wave by a two-dimensional (2-D) periodic array of metallic patches (or apertures in a metallic screen) embedded in a layered medium. The topology of the equivalent network is rigorously derived in the analysis and all the network parameters are given in closed form. In contrast with the previously reported explicit circuit models, the proposed approach accounts for dynamical effects over a very wide frequency range, which enables the application of the model to a great variety of situations. The key advantages of the reported multimodal network representation are its analytical nature, its extremely low-computational cost and that the physical phenomena involved in the scattering can be easily understood in terms of transmission line and lumped circuital reasonings.
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