title: Millimeter-wave phase resonances in compound reﬂection gratings with subwavelength grooves.
abstract: Experimental evidence of phase resonances in a dual-period reﬂection structure comprising three subwavelength grooves in each period is provided in the millimeter-wave regime. We have analyzed and measured the response of these structures and show that phase resonances are characterized by a minimum in the reﬂected response, as predicted by numerical calculations. It is also shown that under oblique incidence these structures exhibit additional phase resonances not present for normal illumination because of the potentially permitted odd ﬁeld distribution. A satisfactory agreement between the experimental and numerical reﬂectance curves is obtained. These results conﬁrm the recent theoretical predictions of phase resonances in reﬂection gratings in the millimeter-wave regime, and encourage research in this subject due to the multiple potential applications, such as frequency selective surfaces, backscattering reduction and complex-surface-wave-based sensing. In addition, it is underlined here that the response becomes much more complex than the mere inﬁnite analysis when one considers ﬁnite periodic structures as in the real experiment.
authors.affiliation: Millimeter and Terahertz Waves Laboratory, Universidad Pública de Navarra, Campus Arrosadía, 31006 Pamplona, Spain.
authors.forename: Miguel
authors.initials: M
authors.lastname: Beruete
authors.forename: Miguel
authors.initials: M
authors.lastname: Navarro-Cía
authors.forename: Diana C
authors.initials: DC
authors.lastname: Skigin
authors.forename: Mario
authors.initials: M
authors.lastname: Sorolla