L-3 Corporation
L-3 ESSCO
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Sandwich

View the Radome Sandwich Table

ESSCO sandwich radomes are rigid, self-supporting structures designed to provide outstanding electromagnetic performance for specific frequency bands.

Applications
Sandwich radome applications are reserved for sophisticated 3-D air surveillance radar for military and commercial SATCOM and civilian air traffic control applications. Other applications include weather radar, phased-array radar and secondary surveillance radar. Standard wind speed design is 150 mph (240 kph); optional designs of up to 250 mph (400 kph) are available.

Construction and Materials

ESSCO sandwich radomes are constructed of doubly-curved polygonal panels that are bolted together from inside the radome to form a truncated sphere. Individual panels can be either four-sided or polygonal, depending on electromagnetic requirements. Panel connections are designed to provide structural continuity and weather tightness while minimizing transmission loss.

The sandwich shell is constructed using highly developed composite materials (i.e., sophisticated cloth weaves, resins and foams) to optimize panel consistency and strength. We exclusively use pre-impregnated (prepreg) materials for the surface skins to control both skin thickness and resin content. Unlike a “wet layup” process” used by most people in the industry, the use of prepreg allows us to provide improved weight to strength ratios in our laminate leading to a higher quality product, with more even resin content. Prepreg provides significantly better fatigue resistance with less void content in the laminate, and better fiber alignment resulting in greater structural strength. It also allows us to control laminate thickness, with very low thermal expansion, which is crucial to obtaining specified electromagnetic performance.

Each panel core — which most commonly consists of polyurethane foam for larger radomes or honeycomb for smaller radomes — is fully enclosed by the surface skins to make the panel weather-tight. Both A-type (three-layer) and C-type (five-layer) construction is available. By varying the skin and core thickness, it provides for optimum performance at the desired operating frequencies.

The panels include reinforced panel edges tuned (impedance-matched) to the specific operating frequency that when assembled, form an overlapping joint with connecting fasteners acting in shear. The outside overlap flange design allows for panel assembly to take place inside the radome and easy panel removal for replacement or repair.

Additional facts:

  • Easy to install
  • Hydrophobic coatings for enhanced high-frequency performance in rain
  • Customized shapes for reduced tower loads or radar cross section

Electromagnetic Performance
ESSCO sandwich radomes perform well over relatively narrow frequency bands or potentially at multiple discrete frequencies. The electromagnetic performance of a sandwich radome is made up of loss or scattering attributable to 1) the central part of the panel window area and 2) the panel flanges. Proper material selection and manufacturing techniques can largely address the first of these factors.

Loss and shift of phase due to the second factor (i.e., the panel flanges) can be nine times that of the panel window area. As a result, the flanges must be tuned or impedance-matched to the window area. Using proprietary tuning techniques, ESSCO has been able to optimize performance of both the window area and the flange over specific frequency bands.

The following chart provides typical electromagnetic performance data.

Typical Transmission Loss vs. Frequency of Tuned Sandwich Radomes
If you are interested in receiving a quote from ESSCO for your new radome please click here.  If you are a customer in the EU and are interested in receiving a quote for your new radome please click here.
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