Electromagnetic wave characteristics of composite frequency selective surfaces with patch-grid-patch type structure fabricated by e-beam deposition

Abstract

In this study, a new method of fabricating a composite frequency selective surface (FSS) using an e-beam evaporator is proposed. The FSS is designed and fabricated as a part of the structure surface. A new concept of FSSs integrated into a composite skin structure provides a design that is electrically and structurally effective. This manufacturing process has the advantage of direct application of FSS function in a real structural surface with varied conformal skin. The multilayered FSSs of the patch-grid-patch type consist of a copper layer as a capacitive or inductive surface on a glass/epoxy pre-impregnated (prepreg) substrate. The copper layer forming the FSS is manufactured using the e-beam deposition on a glass/epoxy prepreg. The bandwidth of the designed FSS increases three times. The difference between the simulated and the measured results is due to the different evanescent wave interactions between the capacitive layers and inductive layer such as the local misalignment of the patch and grid, size of the specimen, and change in the thickness of the dielectric substrate after the manufacturing process. The bandwidth is successfully modified by correcting the design parameters such as the period, patch gap, grid width, and dielectric thickness. The band-pass filtering and skirt characteristics appear in the experimental results, which agree well with the simulated results. This method is remarkably simple, and the manufactured FSS can function as both a structural skin and an FSS. Moreover, it has the merit of manufacturing simplicity and realization of structural shape.