Onofrio Losito

A Wide-Frequency Model of Metal Foam for Shielding Applications

The use of metal foam continues to grow in terms of research and application. Recently, new developments in the electromagnetic (EM) environment, such as shielding applications, have been proposed. A model of metal foam shielding is developed and discussed in this paper to characterize and simulate the EM shielding behavior. More specifically, the EM characterization has been considered, and experimental shielding effectiveness measurements have been performed. These new double wire-mesh screens, obtained as a development of previously planar shields, allow the design of metal foam EM shields, showing good agreement results among this model, some prototype of this model, and metal foams. The good agreements among data pave the way to improve the model for the low-frequency metal foams behavior.

Feasibility Investigation of Low Cost Substrate Integrated Waveguide (SIW) Directional Couplers

In this paper, the feasibility of Substrate Integrated Waveguide (SIW) couplers, fabricated using single-layer TACONIC RF-35 dielectric substrate is investigated. The couplers have been produced employing a standard PCB process. The choice of the TACONIC RF-35 substrate as alternative to other conventional materials is motivated by its lower cost and high dielectric constant, allowing the reduction of the device size. The coupler requirements are 90-degree phase shift between the output and the coupled ports and frequency bandwidth from about 10.5GHz to 12.5GHz. The design and optimization of the couplers have been performed by using the software CST Microwave Studio c ∞ . Eight difierent coupler conflgurations have been designed and compared. The better three couplers have been fabricated and characterized. The proposed SIW directional couplers could be integrated within more complex planar circuits or utilized as stand-alone devices, because of their compact size. They exhibit good performance and could be employed in communication applications as broadcast signal distribution and as key elements for the construction of other microwave devices and systems.

Dual-Band Substrate Integrated Waveguide Resonator Based on Sierpinski Carpet

In this paper, a dual-band Substrate Integrated Waveguide (SIW) resonator with Sierpinski fractal geometry is proposed. The space-filling property of the employed fractal shape allows to reduce the resonator size. The bandwidth, the minimum insertion loss, the maximum return loss and the stop band rejection are considered for evaluating the effect of the fractal geometry on the resonator characteristics. An accurate electromagnetic investigation is made using a full wave finite element method solver (Ansoft HFSS). Simulated and measured results are in good agreement. The second iteration fractal resonator exhibits two simulated bands centered at the frequencies f1 =1 1.57 GHz and f2 =2 5.7 GHz, while the measured frequencies are f1 =1 1.33 GHz, f2 =2 3.67 GHz. The measured bandwidths are BW = 1.15 GHz and BW = 2 GHz and the minimum insertion losses are close to −1.36 dB and −1.97 dB, respectively. The prototypes of the square resonator without, with first and with second iteration fractal geometry are fabricated via standard printed circuit board process (PCB). A Rogers Duroid 5880 substrate with thickness t =0 .381 mm is employed.

An analytical 3D model of metal foams for EM shielding applications

In this paper a preliminary electromagnetic shielding behaviour of metal foams, is developed and discussed. Metal foams represent a novel class of materials which promise new interesting properties employable for various purposes. More specifically, the realization of electromagnetic shields has been considered and experimental Shielding Effectiveness (SE) measurements have been performed, demonstrating very good performance. In order to allow the design of metal foam EM shields, double 3D wire-mesh screens, obtained as a development of a previously 2D laminated shield, has been presented, comparing the relative results with experimental measure. The good agreement among the preliminary data paves the way to obtain an efficient analytical model of the complex electromagnetic behavior of metal foams.

A 3D model of wide frequency metal foam shielding

The use of metal foam continues to grow up in terms of research and application also in electromagnetic environment, such as shielding applications. Considering these new applications an analytical 3D model of metal foams (3D wire-mesh screens) is developed and discussed in this paper to characterize electromagnetic shielding behaviour. More specifically, the electromagnetic characterization has been considered, and experimental shielding effectiveness (SE) measurements have been performed. This 3D model, allow the design of metal foams EM shields, showing good agreement results between this model, some prototype of this model, and metal foams.

Multiple rhombus monopole antenna

Multiband and wideband monopoles constitute a research topic strongly motivated by the growing frequency spectrum needs in the area of wireless communication applications. In this paper, a multi-band, multiple rhombus shaped, monopole antenna is proposed as an alternative to the circular/elliptical disk/ring monopoles for broadband application. The simulation results are in good agreement with the measurement, showing a multiband behavior with good radiative properties. The scattering parameter S11 exhibits four resonant frequencies close to f=1.68 GHz, 3.38 GHz, 6.58 and 13.85 GHz. The measured gain at these resonant frequency are respectively G= 3.1 dB, 4 dB, 6.3 dB, 6.9 dB.

Travelling Planar Wave Antenna for Wireless Communications

Microstrip antennas are one of the most widely used types of antennas in the microwave frequency range, and they are often used in the millimeter-wave frequency range. Actually as the demand for high data rates grows and microwave frequency bands become congested, the millimeter-wave spectrum is becoming increasingly attractive for emerging wireless applications. The abundance of bandwidth and large propagation losses at millimeter-wave frequencies makes these bands best-suited for short-range or localized systems that provide broad bandwidth. Automotive radar systems including cruise control, collision avoidance and radiolocation with operation up to 10 GHz have a large market potential in the near future of millimetre wave applications.

Processing of EMC data with factor analysis

Large amount of data are obtained from simulation or experimental activities. In most cases they are not of easy interpretation; factor analysis provides a tool to highlight those situations of major interest in EMC related to interaction mechanisms between electrical, geometrical and mechanical parameters. The case of field to cable coupling, a typical immunity problem, is presented to illustrate the procedure which can easily be extended to more complex situations including conducted and radiated emission patterns.

Earth Long-Wave Infrared Emission, New Ways to Harvest Energy

This chapter summarizes the physical properties of THz antennas, provides a summary of some of the most important recent developments in the field of energy harvesting of Earth long-wave infrared radiation, discusses the potential applications and identifies the future challenges and opportunities. In particular, a THz antenna is designed in order to transform the thermal energy, provided by the Sun and re-emitted from the Earth, in electricity. The proposed antenna is a square spiral of gold printed on a low cost dielectric substrate. Simulations have been conducted in order to investigate the behavior of the antenna illuminated by a circularly polarized plane wave with an amplitude chosen according to the Stefan-Boltzmann radiation law. Moreover, these THz antennas could be coupled with other components to obtain direct rectification of T radiation. As a consequence, these structures further optimized could be a promising alternative to the conventional photovoltaic solar cells.