Luca Perregrini

Dispersion characteristics of substrate integrated rectangular waveguide

Dispersion properties of the substrate integrated rectangular waveguide (SIRW) are rigorously obtained using the BI-RME method combined with the Floquets theorem. Our analysis shows that the SIRW basically has the same guided-wave characteristics as the conventional rectangular waveguide. Empirical equations are derived from the calculated dispersion curves in order to estimate the cutoff frequency of the first two dominant modes of the SIRW To validate the analysis results, an SIRW guide was designed and measured. Very good agreements between the experimental and theoretical results were obtained.

On the evaluation of the double surface integrals arising in the application of the boundary integral method to 3-D problems

In this paper, the authors discuss how to minimize the computing time for the evaluation of the double surface integrals arising in the application of the boundary integral method (BIM) to three-dimensional (3-D) problems. The integrals considered refer to the Greens functions for the scalar and vector potentials and to uniform or linear basis and test functions defined over triangular sub-domains. The authors report original analytical formulas for the double surface integrals over coincident triangles involving the singular terms of the Greens functions and present a criterion for obtaining a good compromise between accuracy and computing time in numerical integration.

Modeling of Conductor, Dielectric, and Radiation Losses in Substrate Integrated Waveguide by the Boundary Integral-Resonant Mode Expansion Method

This paper presents the modeling of lossy substrate integrated waveguide interconnects and components by using the boundary integral-resonant mode expansion method. The extension of the numerical technique to account for conductor, dielectric and radiation losses is discussed. Moreover, a systematic investigation of the different contributions of loss and their dependence on some geometrical parameters is performed in the case of interconnects and components, aiming at minimizing the losses. The physical explanation of the different effects is also provided. Finally, the validity of the equivalent waveguide concept is extended to the case of lossy interconnects and components.

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

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.

Analysis of multilayered printed frequency selective surfaces by the MoM/BI-RME method

This paper presents an efficient method for the analysis of printed periodic structures, consisting of a multilayered array of metal patches in a stratified dielectric medium, illuminated by a uniform plane-wave. These structures are widely used as frequency selective surfaces and mirrors. The analysis is based on the solution of an integral equation by the method of moments (MoM) with entire-domain basis functions. The basis functions are calculated numerically by the boundary integral-resonant mode expansion (BI-RME) method. The patches may have an arbitrary shape, and both metal conductivity and dielectric losses are considered. Some examples are reported to show the accuracy and rapidity of the proposed method.

Deep-space antenna for Rosetta mission: design and testing of the S/X band dichroic mirror

The paper presents the design, fabrication, and testing of a dichroic mirror to be operated in the deep-space antenna of the European Space Agency in Perth, Australia. The dichroic mirror is designed for combining the signals in the S and X bands in the beam-waveguide feeding system of the 35 m reflector antenna. The final design consists of a thick metal plate of 2.5 m in diameter, perforated periodically with rounded cross-shaped holes. The design of such a structure required a trade off between electrical, mechanical, and technological constraints. The design and testing of a validation sample as well as of the final mirror are discussed.

A Novel Substrate Integrated Coaxial Line (SICL) for Wide-Band Applications

A novel substrate integrated coaxial line (SICL) is presented and experimentally verified in this paper. This structure exhibits unimodal operation over a wide frequency band, is shielded and not dispersive, can be fabricated by using simple, low-cost thin-film process, and can be easily integrated with active devices. Moreover, the same technology results particularly suitable to realize passive components for wideband applications. The design of a Lange coupler with operation bandwidth of 66%, to be used in a multi-port impulse radio for ultra wide band applications, is reported

An innovative modelization of loss mechanism in silicon integrated inductors

In this paper, we present an improved lumped-element equivalent circuit of silicon integrated inductors, which accurately takes into account parasitic effects and separately models the effect of metal and substrate losses. We describe an efficient procedure to deduce all the elements of the equivalent circuit from wideband, two-port measurements of the S-parameters of the inductor. The separate characterization of metal and substrate losses allows us to evaluate separately their contribution to the inductors Q-factor. We also report the results of the characterization of some CMOS and BiCMOS integrated inductors designed to be included in radio frequency integrated circuits operating at 1.8 GHz.

Design and Testing of Frequency-Selective Surfaces on Silicon Substrates for Submillimeter-Wave Applications

A new class of frequency-selective surfaces (FSSs), to be used as quasi-optical filters for harmonic suppression in submillimeter-wave frequency multipliers, is proposed and experimentally verified. The FSSs consist of two-dimensional aperture arrays and are made from microstructured aluminum on electrically thick, high-resistivity silicon substrates. This leads to a very good mechanical stability, reasonably low insertion loss, and permits manufacture of the structure by using standard processes available from the semiconductor industries. This paper presents the design, fabrication, and testing of two sets of prototypes, the former with a passband at 300 GHz and a stopband at 450 GHz and the latter with a passband at 600 GHz and a stopband at 750 GHz. For both frequency ranges, FSSs with rectangular slots and with dogbone-shaped holes have been designed by using the method of moments/boundary integral-resonant mode expansion method. The effect of ohmic and dielectric losses has been determined by using the commercial code HFSS. Several prototypes have been fabricated, and measured by terahertz time-domain spectroscopy and continuous wave measurements, showing high reproducibility of the machining process, insertion loss between 1.0 and 1.6 dB, and stopband attenuation larger than 30 dB. Finally, we demonstrate that the incidence angle can be used as a degree of freedom for fine tuning the stopband, without practically changing the frequency response in the passband

Efficient calculation of the dispersion diagram of planar electromagnetic band-gap structures by the MoM/BI-RME method

The characterization of planar electromagnetic band-gap structures requires the calculation of the dispersion diagram of the modes supported by the periodic structure and the phase of the reflection coefficient under plane-wave illumination. We present a novel method for the calculation of the dispersion diagram. The electromagnetic analysis is based on the method of moments/boundary integral-resonant mode expansion (MoM/BI-RME) method and leads to the formulation of a homogeneous matrix problem. The solution of this problem is performed by an iterative procedure: for a given value of the propagation phase constant, the frequency range is scanned to find the frequencies where the field equation has a nontrivial solution. The search of these frequencies is based on the tracking of the eigenvalues in the complex plane, and proved more efficient than other classical methods (direct search of the determinant zeros, singular value decomposition). The reflection coefficient can be readily determined by using the MoM/BI-RME method, already developed for the analysis of the scattering from frequency selective surfaces. The method is applied to the characterization of the classical uniplanar compact photonic-bandgap structure, and analysis results show the accuracy of the method, its efficiency, and its convergence properties.