Aramid/epoxy composites sandwich structures for low-observable radomes

Low-observable radomes are usually made of E-glass/epoxy composite due to its low dielectric constant which is necessary not to interfere electromagnetic (EM) wave transmission characteristics. Since aramid fibers have lower dielectric constant and higher strength than those of E-glass fiber, aramid fiber radome structures may have better the EM transmission and mechanical characteristics than those of E-glass/epoxy radomes. In this work, the low-observable radome was constructed with a sandwich construction composed of aramid/epoxy composites faces, foam core and Frequency Selective Surface (FSS) which had the abilities of transmitting EM waves selectively in the X-band range. The EM wave transmission characteristics of the low-observable radome were simulated by a 3-dimensional electromagnetic analysis software and also measured by the free space measurement method with respect to the pattern size of FSS and foam cores. The mechanical properties of the low-observable radome made of aramid/epoxy composite were measured by the 3-point bending test and compared to those of the conventional low-observable radome made of E-glass/epoxy composite.

► The sandwich radome structures for the low-observable radome with aramid/epoxy composite.
► The dielectric properties of the aramid/epoxy composite measured by the free space measurement method.
► Electromagnetic wave transmission characteristics of the radome was simulated and measured.
► The maximum thickness of aramid/epoxy composite for the face and the Frequency Selective Surface (FSS) were determined.
► The flexural strength and specific flexural strength were higher than conventional E-glass composite radome.