Emilio Arnieri

A Compact High Gain Antenna for Small Satellite Applications

The development of a circularly-polarized compact high-gain antenna to be used for the European Student Earth Orbiter small satellite mission is described. The antenna is realized stacking two coaxial shorted annular patches and placing the top one at half a wavelength from the lower one. At variance of other similar configurations proposed in the past, the one presented in this paper has several important features which can be extremely useful for application in the space environment. In particular, it can be easily fabricated employing suspended technology and its radiation characteristics are to some extent controllable by opportunely varying the geometry. In the following, a straightforward design procedure will be presented detailing the criteria to optimize top and bottom radiating elements. Both numerical and measured results will show that the proposed design satisfies the specifications and presents characteristics comparable to other larger and heavier solutions usually more difficult to design. Specifically, it will be shown that with this configuration it is possible to obtain gain values higher than 12 dB using ground plane of moderate size and that a further improvement up to 15dB can be obtained employing larger ground planes

Analysis of Substrate Integrated Waveguide Structures Based on the Parallel-Plate Waveguide Green's Function

This paper presents the full-wave characterization of substrate integrated waveguide structures. Substrate integrated circuits are considered as an ensemble of conducting posts placed in a parallel-plate waveguide and are analyzed in terms of the cavities formed by the top and bottom conducting plates and by the walls of the metallic vias. The field inside the parallel-plate waveguide is computed by considering the dyadic Greens function expressed as an expansion in terms of vectorial cylindrical eigenfunctions and considering the scattering from the ensemble of conducting posts. Coaxial or waveguide ports are included in the analysis as equivalent magnetic current distributions. Self-admittance and mutual admittance are calculated in a form that separates the parallel-plate contribution from the field scattered by the posts. Results relevant to structures already presented in literature will be shown and compared with simulations obtained with one of the most used articles of commercial software. It will be shown that an excellent agreement with published results is achieved together with significant improvements both in computational time and memory requirements.

Method of Moments Analysis of Slotted Substrate Integrated Waveguide Arrays

A method of moments analysis is described for substrate integrated waveguide slot arrays. The array structure is modeled as a parallel plate waveguide on which via holes and slots are created. The field into the waveguide is expressed by the sum of the parallel plates contribution and the field scattered by the metallic through holes, with both contributions expressed by means of an expansion in terms of vectorial cylindrical eigenfunctions. The slots are modeled as unknown equivalent magnetic current distributions which are found by solving an integral equation derived from the continuity of the field on the slot surface. Antenna arrays already presented in the literature will be analyzed, and the results compared with HFSS simulations. It will be shown that the proposed method is efficient and gives results in excellent agreement with the most common simulation tools.

Resonant Frequencies of Circular Substrate Integrated Resonators

In this letter, the characterization of circular resonators realized in substrate integrated waveguide technology is presented. Resonances are found by setting up the equations of the scattering for an ensemble of metallic posts in parallel plates waveguide and considering the nontrivial solution to the corresponding homogeneous problem. Resonant frequencies are then located by means of an efficient strategy, based on an estimate of the minimum singular value. In the last part of the letter a data fit formula of practical use is presented for circular resonators with a wide range of geometrical and electrical parameters resonating on TM010 and TM110 modes.

Fast Nonlinear Eigenvalues Analysis of Arbitrarily Shaped Substrate Integrated Waveguide (SIW) Resonators

In this paper, the problem of evaluating resonant frequencies of arbitrarily shaped substrate integrated waveguide resonators is considered. Resonances are found regarding them as nonlinear eigenvalues of the operator describing the scattering by metallic posts in a parallel plate waveguide. Nonlinear eigenvalues are usually computed by singular value decomposition. In order to save computational time, we propose an alternative approach derived by some general consideration on the theory of nonlinear eigenvalue problems in the discrete case. Results on rectangular, circular, and elliptical cavities are presented and compared with High Frequency Structure Simulator software package simulations. It is shown that the proposed method is efficient and accurate.

Analysis of Lossy SIW Structures Based on the Parallel Plates Waveguide Green's Function

In this paper, a full-wave analysis technique of lossy substrate integrated waveguides, based on the dyadic Greens function of the parallel plate waveguide, is presented. The fleld inside the waveguide is expressed in terms of cylindrical vector wave-functions and the flnite conductivity of the top and of the bottom plates, and of the metallic vias are taken into account. Losses into the dielectric substrate are also included. Coaxial ports are considered as sources and self and mutual admittances are evaluated. Cases of practical structure taken from literature are presented showing a very good agreement with the most used commercial software.

Support Vector Regression Machines to Evaluate Resonant Frequency of Elliptic Substrate Integrate Waveguide Resonators

In this paper an efficient technique for the determination of the resonances of elliptic Substrate Integrated Waveguide (SIW) resonators is presented. The method is based on the implementation of Support Vector Regression Machines trained using a fast algorithm for the computation of the resonant frequencies of SIW structures. Results for resonators with a wide range of parameters will be presented. A comparison with results obtained with Multi Layer Perceptron Artificial Neural Network and with full wave simulations will show the effectiveness of the proposed approach.

TWO DIMENSIONAL MULTI-PORT METHOD FOR ANALYSIS OF PROPAGATION CHARACTERISTICS OF SUBSTRATE INTEGRATED WAVEGUIDE

In this paper, two dimensional multi-port method is used to analyze substrate integrated waveguide by using Greens function approach to obtain the impedance matrix of equivalent planar structure. Modes propagation constant of substrate integrated waveguide, as a periodic structure, is calculated by applying Floquets theorem on the impedance matrix of a unit cell. Field distribution of the propagating mode is obtained by this method. Results obtained by this method are verifled, in a broad range of dimensions, by comparing with published results and also those calculated by commercial electromagnetic simulator, HFSS. Electromagnetic band gaps and mode conversion phenomenon as properties of periodic structures are also observed and investigated. Mode conversion in SIW is reported for the flrst time by our proposed method.

A Ka-Band Dual-Frequency Radiator f>or Array Applications

In this letter, a dual-band antenna is proposed for use as an element in Tx/Rx Ka-band arrays. The antenna consists of a shorted annular patch (SAP) antenna integrated with a circular radiating waveguide. The SAP is fed with a stripline coupled through a slot, while for the waveguide, an E-plane stripline probe is used. This letter presents the design of the dual-band element, along with simulated and measured results. It will be shown that the proposed antenna possesses good electrical characteristics and that it can be realized using standard printed technologies.

COMPUTATION OF THE RESONANT FREQUENCY AND QUALITY FACTOR OF LOSSY SUBSTRATE INTEGRATED WAVEGUIDE RESONATORS BY METHOD OF MOMENTS

This paper presents a technique for the e-cient and accurate determination of resonant frequencies and quality factors of Substrate Integrated Waveguide (SIW) resonators. To consider resonators of a general shape the SIW structure is modelled as a parallel plate waveguide populated with metalized via holes. The fleld into the SIW cavity is found by solving the scattering problem for the set of vias into the parallel plate. Resonances are determined searching for the complex frequencies for which the determinant of the system of equations pertinent to the scattering is zero. To speed up the search, a flrst guess for the resonance frequency is found using an estimate of the minimum singular value of the system of equations. A Muller search in the complex plane is later used to accurately determine both frequencies and quality factors. Results relevant to resonators of various shapes are presented and compared with results obtained with a commercial code.