Showing papers by "Luca Perregrini published in 2001"

Efficient analysis of quasi-optical filters by a hybrid MoM/BI-RME method

Abstract: This paper presents a novel algorithm for the analysis of quasi-optical filters, consisting of thick metal screens perforated periodically with arbitrarily shaped apertures. The algorithm is based on the widely used method of moments (MoM) in conjunction with entire domain basis functions. Its flexibility, accuracy, and rapidity depend on the use of the boundary integral-resonant mode expansion (BI-RME) method in the numerical determination of the basis functions. A computer code has been developed based on this algorithm. The analysis of two different quasi-optical filters operating at 8 GHz and 280 GHz is reported and compared with experimental data as well as with other simulations. In both cases, the whole analysis requires few seconds on a standard workstation and the theoretical results show a very good agreement with the measured data in a wide frequency band. The capability of the MoM/BI-RME approach to handle completely arbitrary shapes is highlighted in the second example. In this case, in fact, the fabrication process causes small deformations of the nominal shape of the apertures, which must be accounted for, since they play an important role in the frequency response of the filter.

MoM/BI-RME analysis of boxed MMICs with arbitrarily shaped metallizations

Abstract: In this paper, we propose a novel approach for the analysis of shielded microstrip circuits, composed of a number of thin metallic areas with arbitrary shapes and finite conductivity, embedded in a multilayered lossy medium The analysis is based on the solution of an integral equation (IE) obtained by enforcing the proper boundary condition to the electric field on the metallic areas The IE is solved by using the method of moments with entire domain basis functions, which are numerically determined by the boundary integral-resonant-mode expansion (BI-RME) method The use of the BI-RME method allows for the efficient calculation of the basis functions independently on the shape of the domain, thus permitting the analysis of a wide class of circuits Two examples demonstrate the accuracy, rapidity, and flexibility of the proposed method

Efficient analysis of FSSs with arbitrarily shaped patches by the MoM/BI-RME method

Abstract: Frequency selective surfaces (FSS) operating in the microwave and millimeter-wave region may consist of either a periodic array of apertures in a metal screen (inductive FSS) or a periodic array of patches on a dielectric layer (capacitive FSS). We have proposed an efficient algorithm for the analysis of inductive FSS, both in the case of thin and in the case of thick metal screens. This algorithm is named the MoM/BI-RME method and is based on the method of moments (MoM) applied with entire-domain basis functions, which are very efficiently calculated by the boundary integral-resonant mode expansion (BI-RME) method. In this paper, we present the application of the MoM/BI-RME method to the analysis of capacitive FSS. The patches may have an arbitrary shape, and losses in both the dielectric medium and the conductors can be accounted for.

Characterization of Heterostructure-Barrier-Varactors for Frequency Multiplication

Abstract: This paper presents the fabrication and characterization of four-barrier planar heterostructure-barrier-varactors (HBVs) to be used in frequency triplers. The fabrication process and the DC and RF testing results are discussed. The measured results are evaluated by a newly developed combined genetic algorithm/harmonic balance simulator to calculate the optimum impedance and output power at 255 GHz. Different HBV structures were fabricated, and a comparison of their conversion efficiency is presented.

Analysis of Multigrid Frequency Selective Surfaces by the MoM/BI-RME Method and the Segmentation Technique

Abstract: This paper presents a novel method for the analysis of frequency selective surfaces (FSSs), consisting of one or more thick metal screens perforated periodically with arbitrarily shaped apertures. Basically, this method applies the segmentation technique, thus reducing the computational effort to the analysis and the combination of a number of waveguide step discontinuities. The analysis of the waveguide step discontinuities is performed by the MoM/BI-RME method. Some examples are reported and compared with experimental data.

MoM/BI-RME analysis of boxed microwave circuits based on arbitrarily shaped elements

Abstract: In this paper, we propose a novel approach for the analysis of shielded microstrip circuits, composed of a number of thin metallic areas with arbitrary shapes and finite conductivity, embedded in a multilayered lossy medium. The analysis is based on the solution of an Integral Equation (IE) obtained by enforcing the proper boundary condition to the electric field on the metallic areas. The solution of the IE is obtained by the Method of Moments (MoM) with entire domain basis functions, which are numerically determined by the Boundary Integral-Resonant Mode Expansion (BI-RME) method. The use of the BI-RME method allows for the efficient calculation of entire domain basis functions in the case of metallic areas with arbitrary shapes, thus permitting the analysis of a wide class of circuits. Two examples demonstrate the accuracy, rapidity, and flexibility of the proposed method.

Deep space antenna for Rosetta mission: design of the S/X band dichroic mirror and analysis of the beam waveguide

Abstract: The design of a dichroic mirror operating in S/X band for the Rosetta mission is described. In order to achieve the required performance, a trade-off between electrical and mechanical problems was necessary. So the shape of the holes in the dichroic plate was chosen according to good electrical performances in terms of cross-polar level and insertion losses and to acceptable mechanical deformations of the plate itself. Furthermore, a sample of the designed perforated mirror was manufactured and measured in an anechoic chamber. Software (GRASP8) simulations evaluated the impact of the dichroic plate on the electrical performances of the beam waveguide feeding the shaped Cassegrain antenna.