Overview
The C-RAM HPA is a hollow pyramidal RF absorber designed to provide high levels of absorption in high power applications. Typical uses include the hot spots in test rooms or anechoic chambers where heating due to concentrated power might damage conventional materials or lead to danger of smoke and fire. Power densities of up to 2 W/in2 have been handled successfully. C-RAM HPA is usually used with other products such as C-RAM SFC or C-RAM EVA in an anechoic chamber application.
Consists of lightweight, hollow pyramids. The pyramids are formed by folding relatively thin sheets of lossy foam plastic into shape and bonding them to a foam back panel. As an option, small vent holes may be bored through the walls of the absorber, allowing forced cooling air to be blown through the piece from behind.
TYPICAL PROPERTIES
The table on the reverse side gives dimensions, weights and reflectivity characteristics of the two grades of C-RAM HFP.
FIRE RETARDANCY
Meets the fire retardancy requirements of NRL Specification 8093, tests 1, 2, and 3, as well as those of MIT document MS-8-21 tests 1, 2, and 3, and T.I> drawing 2693066.
METHOD OF APPLICATION
Bonded to walls and ceiling of a test room using polychloroprene adhesive or Velcro fasteners, in the same way as normal CRAM SFC pieces would be mounted. Details of mechanical mounting schemes can be provided for applications where forced air cooling is required.
Pieces can be readily trimmed with a bandsaw, but cutting pieces to fit should be minimized, as the full structure of the piece is required to support the hollow pyramid.
AVAILABILITY
C-RAM HPA is available in two height grades as given in the table below. Both grades come in a standard 610 x 610 mm (24 inch x 24 inch) base size, and both have four individual pyramids per piece. Depending upon the application and the room dimensions, Cuming Microwave engineers can help you size the proper absorbing material and can advise of methods of using forced air cooling.
TYPICAL PHYSICAL AND REFLECTIVITY CHARACTERISTICS OF C-RAM HPA | |||||||||
GRADE | HEIGHT in. (mm) | WEIGHT Lbs. (kg) | TIPS PER PIECE | Reflectivity in dB at Frequency (GHz) | |||||
0.03 | 0.10 | 0.30 | 1.0 | 3.0 | 10.0+ | ||||
HPA-36 | 38 (965) | 12 (5.5) | 4 | -5 | -25 | -35 | -45 | -50 | |
HPA-48 | 50 (1270) | 16 (7.3) | 4 | -5 | -10 | -30 | -45 | -50 | -50 |