Wait-Hill MoM for a lumped element loaded mesh screen on a stratified substrate

The generalized thin-wire Wait-Hill method of moments formulation in free space is extended to model plane wave scattering from a lumped element periodically loaded mesh screen backed by a multi-layer substrate. It is numerically demonstrated that the sawtooth function methodology proposed by Hill and Wait for reducing the computation time is applicable. Furthermore, for the case of an electrically dense mesh, a simple analytical expression for the transmission coefficient is obtained

Design of complementary reflectarray

A novel solution for the manufacture of a reflectarray antenna is presented. The unit cell simply consists of dielectric foam inserted between two thick metallic plates. The plate illuminated by the feeder is a 0.5 mm-thick stainless steel sheet into which the C and the reverse C slots are laser cut. This solution allows one to obtain an efficient, robust and compact antenna with low-cost manufacturing process even for no mass production. Preliminary measurements show the feasibility of the proposed solution and its performances

2-Dipoles Circularly-Polarized Antenna Integrated in Lamp Holder for Fixed RFID Reader

The paper presents a solution to integrate a circularly polarized antenna in a tracklight housing that contains both a lamp and a UHF-RFID reader. The antenna is located outside the tracklight housing since the cylindrical lamp holder is metallic and small in terms of wavelength, and there is no space enough inside it. Furthermore, the antenna does not interact with the lamp, so no specific lamp is required. The solution makes use of a standard print-circuit-board fabrication technique combined with a low-cost metal sheet cavity, that can be also drilled for aesthetical reasons. An antenna prototype has been designed for the North America market. The measurements showed a reflection coefficient less than -15dB and a gain greater than 6dBi in the band of interest (902-928 MHz)

Optimization of a metallo-dielectric EBG waveguide

n this contribution we have presented a new metallo-dielectric EBG waveguide. The initial concept is based on Bragg fiber, which cross section is usually very large in terms of the wavelength. To reduce the waveguide dimensions and make it feasible at THz frequencies, we use a combination of a metallic and a dielectric waveguide. Standard resonant geometries will have high bend coupling between the TE01 and EH11 modes, thus reducing the losses introduced by the bend. Here we present two ways of optimizing the waveguide structure to break the degeneracy between these modes. One considers the periodicity along ρ and the other along φ. The results can be extended to structures with two or three periods to reduce the metallic losses. These structures will have an overall propagation and bend loss lower than an overmoded circular waveguide working on the TE11 mode

Design of a Low Loss Metallo-Dielectric EBG Waveguide at Submillimeter Wavelengths

In this letter we show the viability of using concentric cylindrically-periodic (CP) dielectrics to realize low-loss propagation at submillimeter wavelengths. Most of the power in the CP Waveguide (WG) is confined to an air core propagating a TE_(01) mode. The TM_(11) mode degeneracy is removed over a very wide bandwidth by a series of periodically spaced dielectric rings that are optimized in thickness and spacing. The new waveguide differs from classical Bragg fibers in that we use only a small number of dielectric layers (2-4), and terminate the outer layer with an external metal coating. We include several designs and describe the optimization procedure that was used to realize structures with low propagation and bend loss

A Simulation Tool to Evaluate the Feasibility of a gasification-I.C.E. System to Produce Heat and Power for Industrial Applications☆

Abstract Combined heat and power (CHP) systems fed by renewable sources are of great interest for efficient and greener energy production in industrial applications. In order to reduce fossil fuel consumption, biomass gasification coupled with I.C.E. is a viable way for ensure constant and accurately predictable renewable energy production. The aim of this work is to evaluate the integration in an industrial context of a CHP system fed by syngas produced from woody biomass gasification in a downdraft reactor. The feasibility study was developed thorough the combination of two simulation programs. Aspen Plus was used for simulating the biomass gasification unit and was exploited in order to determine the syngas composition and flow rate. Results have been employed in TRNSYS, that has instead been chosen for the modeling of the complete CHP system

Optimization-based Design of Isoflux Reflectarray

In this communication, some preliminary results on the design of an isoflux reflectarray, suitable for being mounted on board a satellite or even a CubeSat, carried on with a global optimization technique, are presented. The obtained radiation patterns, relative to a small-medium size configuration, are good and confirm the effectiveness of the proposed procedure

Fast analysis of large finite arrays with a combined multiresolution-SM/AIM approach

We present a synthesis of the sparse matrix/adaptive integral method (SM/AIM) and the multiresolution (MR) approach for the analysis of electrically large finite arrays, with planar or 3-D radiating elements; the two methods were separately introduced previously. The use of the MR has the effect of a preconditioner and speeds up the convergence rate of the SM/AIM of almost two orders of magnitude, with a total reduction of the numerical complexity with respect to the standard MoM of almost three orders of magnitude