Circuital and electromagnetic modeling of bulk and membrane supported lumped elements for microwave and millimeter wave applications

Micromachined configurations suitable of microwave and millimeter wave applications offer great advantages because of their reduced dielectric losses and improved dispersion control[1]. These characteristics are very appealing especially for the millimeter wave range, where the frequency dependence of both, losses and dispersion are enhanced. Presently, the micromachining technology is a challange to obtain low cost, high integration and high performance subsystems useful for future ground and space applications[2,3]. Lumped elements and filters can be realized by means of etching technologies on dielectric[4] and plastic (polymide)[5] membranes. In this paper, circuital and planar electromagnetic simulations have been performed to model the microwave response of micromachined lumped elements on SiO2/Si3N4 /SiO membranes by using commercial software packages. Experimental and theoretical results on lumped elements realized on polymide membranes have been also considered. The main predicted and experimentally checked advantage in using the polymide solution with respect to the usual dielectric trilayer is the increase of the cutoff frequency.