Design procedure for FSS with wide transmission band and rapid rolloff

An aspect of the Fabry Perot interferometer (FPI) approach to designing frequency selective surfaces (FSS) consisting of cascaded layers is applied to the problem of broadening the transmission band while simultaneously maintaining a rapid rolloff to the reflection region of the transmission response. The technique is to bring the pathlength phase and boundary reflectivity phase curves close to coincidence over the required frequency range. The example used is a two-layer semi-airspaced structure, with the resulting design validated experimentally