SHEERGARD Rigid Sandwich Construction Radomes are designed to provide the enclosed system with maximum protection from the environment and minimal effect on the transmission of the RF signal
SHEERGARD Sandwich Radomes provide a rigid self-supporting enclosure that is tuned for optimal electromagnetic performance in a specific frequency range. Tuning is available for the L, S, C, and X frequency bands.
SHEERGARD Sandwich Radomes are constructed using individual panels attached with a joint system that is unique to the radome industry.
The SHEERGARD Sandwich Radome panels use a foam core with fiberglass based inner and outer rigid skins. The thickness and electromagnetic characteristics of the foam core and the skins can have a significant effect on the transmission of the RF signal through the panel window area. The skin and core thicknesses for the panel structure are designed to withstand loads associated with extreme environments such as high winds yet produce excellent electromagnetic performance.
The joints that connect the radome panels together can represent the most significant part of losses attributed to a Sandwich Radome. The unique joint system utilized in the SHEERGARD Sandwich Radome minimizes the need for significant fiberglass reinforcing layers extending into the panel window area. This reduces the effective width of the joint and therefore improves the electromagnetic transmission performance.
The joint system incorporates a plug that is bonded into each edge of the panel. The plugs from adjacent panels are connected using splines during the installation process. The materials for the joint components as well as proprietary tuning techniques are selected to optimize overall radome transmission performance.
The hardware used to connect the splines is embedded into the outer spline. The spline is constructed with a very low profile compared to the panel surface resulting in no significant protrusions from the outer surface that could have the effect of holding ice and snow on the surface
Due to the excellent transmission performance which minimizes scattering of the RF energy by the radome, perturbation of the antenna sidelobe pattern is minimized as well.
Permanent Hydrophobic Surface
Hydrophobicity of a radome outer surface is critical to reducing additional transmission loss during rain conditions. Since water has a high dielectric constant and loss tangent, even a thin film of water on the radome surface during rain conditions will produce much higher transmission losses. A hydrophobic radome surface causes the water to form small beads and to run off in small rivulets instead of forming a sheet of water in front of the entire antenna aperture.
SHEERGARD High Performance radome materials have PTFE as an integral part of the surface. This PTFE surface will maintain its hydrophobic characteristics throughout the life of the radome and never needs recoating or refurbishment. This eliminates the need for the expensive refurbishing of radome surfaces by painting or other time consuming processes. Other types of surfaces that produce an initial hydrophobic effect but eventually lose it over time between refurbishing events will see a gradual deterioration of the transmission performance in the rain. Additionally, as those surfaces receive new coats of material to reinstate their hydrophobicity, that buildup of surface coating contributes to additional dry and wet radome transmission
A secondary effect of the permanent SHEERGARD PTFE surface is that it has much more resistance to snow and ice adhesion than traditional radome surfaces. This combined with the relatively smooth surface provided by the joint spline connection system minimizes the tendency for accumulation of ice and snow throughout the life of the radome. For critical systems this helps to maximize operational time during winter conditions
Testing and Analysis
Saint-Gobain has performed extensive testing and analysis of the SHEERGARD Sandwich Radome panel and joint configurations to assure conformance with system requirements. We have the capability to perform any additional test or analysis work required to analyze specific customer requirements as requested.