Overview
C-RAM SFC is a series of high performance broadbanded RF absorbers made from specially treated low density polyurethane foam. The product is flexible and tolerant of physical abuse. Using a steep pyramid design which provides an impedance gradient, C-RAM SFC provides premium performance in anechoic chambers at both normal and off-normal incidence angles. These products meet all of the fire retardancy requirements of NRL Specification 8093 tests 1, 2, and 3, MS-8-21 tests 1, 2, and 3, and T.I. drawing 2693066, as well as ASTM E-84-97a, Class A.
TYPICAL PROPERTIES
Typical weights, dimensions, and reflectivities of the various grades of C-RAM SFC are given in the tables on the reverse side.
Typically, C-RAM SFC absorbers can handle up to 1.0 W/in2 (2 kW/m2) of RF energy in a temperature controlled room, but this is dependent upon frequency and application.
The product is black throughout, and generally is sprayed with a light blue surface coating, both for cleanliness and to provide better light reflection inside a chamber. The absorber can be left unpainted if requested.
AVAILABILITY
Standard sizes of C-RAM SFC are listed in Table 1, ranging from a 4 inch to 72 inch height. C-RAM SFC-4 up through SFC-40 are shaped as conventional pyramids and supplied as square 24 inch (610 mm) panels. SFC-48 and larger are available as a standard pyramid or in the twisted pyramid design. The “twisted pyramid” design improves the wide angle performance and, because of the extended shoulder height, exhibits less drooping of the tips after installation.
In addition to simply supplying a bill of materials, Cuming Microwave designs and installs complete anechoic chambers. Chambers can be designed to meet your specifications, and an entire kit of materials is supplied, including factory pre-cuts of special fitting parts. We can install all materials or supply technical support to help you complete your own installation.
METHOD OF APPLICATION
Absorber pieces are generally installed in a chamber using solvent-based neoprene contact adhesive. This technique works well for small and medium size products up through SFC-24. These small grades can also be bonded using water based adhesives; however the tack time is long, requiring supports to hold pieces in place while the adhesive dries.
Alternatively, C-RAM SFC up through the 24 inch grade can be supplied with a Velcro backing. Strips of the mating Velcro are bonded to the walls, and the piece is pressed into place, yet can be readily removed.
For large absorber grades, an installation technique using a factory-installed metal base plate and a field installed rail & clip mounting provides the fastest and most reliable installation.
