Domain integral equations for electromagnetic band-gap slab simulations

Trabajo presentado al International Symposium on Electromagnetic Theory, URSI 2004.Electromagnetic band-gap substrates o er advantages regarding cross-coupling in sub-mm range imaging array applications. Electromagnetic scattering by such substrates may e ectively be formulated in terms of integro- di erential equations. The scattered elds are evaluated via the spectral domain in which the 3-D problem reduces to an in nite system of coupled 1-D integro-di erential equations. The associated matrix-vector products are dominated by FFTs. For moderate frequencies an elementary preconditioner in combination with a prudent initial estimate usually su ces to reach rapid convergence using the transpose-free quasi-minimal residual method.The research presented above has been financially supported by ESA/ESTEC, under Contract No. 15632/01/NL/JA

Design and Characterisation of an EGB Imaging Array at Sub-Millimetre Wave Frequencies

In this paper the design and characterisation of an imaging array at 500 GHz based on EBG technology is described. The array is formed by 7 detecting elements placed on a top of a silicon woodpile and uses a paraboloidal mirror as refractive element. Good agreement was obtained between predicted and measured performances

Manufacturing tolerance analysis, fabrication, and characterization of 3-D submillimeter-wave electromagnetic-bandgap crystals

The sensitivity of the characteristic band edge frequencies of three different 500-GHz electromagnetic-bandgap crystals to systematic variations in unit cell dimensions has been analyzed. The structures studied were square bar woodpiles made with dielectric having epsiv rap12 and epsivr=37.5 and two wide bandgap epsivr=37.5 crystals designs proposed by Fan and Johnson and Joannopoulos. These epsivr values correspond to high-resistivity silicon and a zirconium-tin-titanate ceramic, respectively. For the woodpiles, the fractional frequency bandgap varied very little for dimensional deviations of up to plusmn5% from the optimum. The bandgaps of the Fan and Johnson and Joannopoulos structures were affected to a greater extent by dimensional variations, particular sensitivity being exhibited to the air-hole radius. For all crystals, the effect of increasing the amount of dielectric in the unit cell was to shift the bandgap edges to lower frequencies. Both silicon and ceramic woodpiles, along with a ceramic Fan structure, were fabricated and dimensionally characterized. Mechanical processing with a semiconductor dicing saw was used to form the woodpiles, while the Fan structure required both dicing and UV laser drilling of circular thru-holes. Good agreement with predicted normal incidence transmissions were found on the low-frequency side of the bandgap in all cases, but transmission values above the upper band edge were lower than expected in the ceramic structure

Modifications of the woodpile structure for the improvement of its performance as substrate for dipole antennas

The modification of a woodpile structure which allows to improve the radiation pattern of a printed dipole antenna placed on top of it is presented. By displacing the bars closer to the dipole a more symmetric and directive radiation pattern can be obtained. Simultaneously, this modification changes the input impedance of the dipole, bringing it closer to the impedance levels required to be matched to a coplanar stripline

Optimization of a 500 GHz Receiver Using EBG Technology

The optimization of a 500 GHz receiver based on Electromagnetic Band Gap (EBG) technology is presented. The conguration consists of a dipole antenna placed on top of a woodpile structure and utilises a Schottky diode as the detecting element. The inuence of the diode and its substrate chip on the radiation performance has been studied, with the nding that it has to be placed as close as possible to the dipole antenna to avoid distorting the radiation pattern. Measurements are presented which conrm our simulations