2.3_Cuming_Absorber Specifications.pdf

tI cuMrNG MrcRowAVE f^l CORPORATION TECHNICAL DATA

230 BODWELL STREET AVON, MA 02322 (800) 432-6464 (s08) 580-2660 FAX (508) 584-2309

TECHNICAL BULLETIN 390-1

C-RAM SFC

HIGH PERFORMANCE BROADBANDED PYRAMIDAL RF ABSORBER

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

,--' Specifrcation 8093.

TYPICAL PROPERTIES

Typical weights, dimensions, and reflectivities of the various grades of C-RAM SFC are given in the tables on the reverse side.

The product is black throughout, and generalty 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 24inch (610 mm) panels. SFC-48 is available as a standard pyramid or in the twisted pyramid design with an 18x36 inch (457 x 914

mm) base dimension. Larger sizes are a "twisted pyramid" design which iinproves the wide angle performance and, because of the extended shoulder height, exhibits less drooping of the trps after installation.

ln addition to simply supplying a bill of materials, Cuming Corporation 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 frttrng parts. We can install all materials or suppiy technical support to help you complete your own installatton

Document Control No. N-1 5-000-0088-D 2127197 page 1 of 2

METHOD OF APPLICATION

Absorber pieces are generally installed in a chamber usrng 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 drres.

Alternatively, C-RAM SFC up through lhe 24 inch grade, can be supplied wrth a Velcro backing. Strips of the mating Velcro are bonded to the walls, and the piece is pressed rnto place yet can be readily removed.

For large absorber grades, an installation technique using a factory-rnstalled metal base plate and a field installed rarl & clrp mountrng provides the fastest and most relrable installation

TABLE 1

PHYSICAL CHARACTERISTICS AND

TYPICAL REFLECTIVITY AT NORMAL INCIDENCE

GRADE HE IGHT

(mm)ln.

WEIGHT

lbs. (ko)

TIPS PER

PIECE

REFLECTIVITY AT FREQUENCY (GHz)

0.12 0.3 0.5 't.0 3.0 6.0 10 18 36- s0.

SFC.4 4.3 (109) 3 (1 4) 144 30 35 42 50 50 50

SFC-6 6 52 3.5 (1.6) 100 32 40 45 50 50 50

SFC-B 8 IU 4.s (2.0) 64 30 37 45 50 50 50 50 sFc-12 12 305 6 (2.7 36 35 40 45 50 50 50 50

SFC-18 18 AF 12 15 4\ 16 30 37 40 45 50 50 50 >45

sFc-24 24 (610 17 (7.7\ I 30 35 40 45 50 50 50 50 >45 5FU-Jb 36 (914) 24 (10.9) 4 at 37 42 50 50 50 50 50 >45 sFc-40 40 (1016) 39 (18 4 38 43 50 50 50 50 50 50 sFc-48 " 48 (1219) 38 (1 2 10 35 40 50 50 50 50 50 50 >45 >aL- / I 72 (829\ s0 (2 33 40 45 50 50 50 50 50 50 >45

Notes - SFC has been characterized at 36 and 50 Ghz, but is not routinely measured at these frequencies.

--SFC-4Band-T2aregenerallysuppliedrnthe"twrsted" configuration.ThebaseoftheSFC-48 is 18 x 36" (457 x 914 mm). The sFC-72 has the standard 24" (6i0 mm) base

TABLE 2

TYPTCAL REFLECTtVtTy (BtSTAT|C) AT OFF_NORMAL tNCtDENCE

(Multiply numbers in chart by dB values in Table 1)

Absorber height elen goo(oo

The information in this technical bulletin, although believed to be accurate, is not to be taken as a warranty for which Cuming Corporation assumes legal responsibrlity, nor as permrssion or recommendation to practice any patented inventron wlthout license, rt is oifered for verification by the customer, who must make the finaljudgement of suitabrlrty for any application

Document Control No N-15-000-0088-D 2127197 page 2 of 2

5 Oft-norma le (0" = normal, 90" = 45" 50' 55 60" 65 70 /5 80

4.0 1.00 0.95 0.86 0.75 070 0.60 0 51 043

2.0 non 0.82 0.74 0.66 0.58 0.49 o42 034

1.0 iaa 0.65 0.58 0.50 0.44 0.37 0.31

0.5 048 0.43 0.37 031 0.25 4.20 f^ltI cuMrNG MrcRowAVE

CORPORATION TECHNICAL DATA

230 BODWELL STREET AVON, MA 02322 (800) 432-6464 (508) 580-2660 FAX (508) 584-2309

TECHNICAL BULLETIN 390.2

C.RAM SFC WEDGE

HIGH PERFORMANCE WEDGE SHAPED ABSORBERS

C-RAM SFC-WEDGE is a series of high performance broadbanded absorbing materials of wedge configuration. SFC-WEDGE complements the pyramidal SFC product, and is made using the same process and materials.

SFC-WEDGE therefore posess the same desirable properties including fire retardancy compliance with NRL-8093 Tests 1, 2 and 3.

C-RAM SFC-WEDGE is primarily designed for use in special applications where energy is driected in a desired path, as in the case of energy propagation down the taper of a tapered chamber, and on chamber side walls, ceiling and floor where energy is guided to a pyramidal absorber on the back wall. The wedge design eliminates backscatter at these high incidence angles.

An added feature SFC-WEDGE is that the reflectiviiy performance at near normal incidence angles is close to that of the pyramidal SFC product, but due to the wedge geometry, the product is polarization sensitive. The performance versus frequency is listed below, materialwill perform as the pyramidal materialof same height "H" but with reflectivity values that are2to 4dB less. This 2 to 4dB difference is largely due to the polarization of the wedge geomeiry.

TYPICAL PROPERTIES

Dimensions and weights of the various grades of SFC WEDGE are given in Table 1 below.

Typical reflectivity of the various grades is given in Table 2 below.

Material is black throughout, surfaces are painted blue. Standard method of attachment is the same as for C-RAM SFC.

AVAILABILITY

C-RAM SFC-WEDGE is available in four standard grades, 6, 8, 12, and 18 inches tall.

Grades larger than 1B inches are available as special order.

All grades have a 24 inch x 24 inch (61 0 x 61 0

mm) base size. Parts can be factory cut to special shapes and mitres. ln addition, pre-designed tapered chamber kits are available with all necessary pre-cuts.

Document Control No. N-1 5-000-0126-4 2119197 page 1 of 2

TABLE 1 -. SFC WEDGE PHYSICAL DATA

Grade Base Dimension

Height Wedge Rows per piece

Weight

SFC.6 WEDGE 24 x24 n 6 in. 10 4.3 lbs.

SFC.8 WEDGE 24 x24 n 8 in. 8 5.3 lbs.

SFC-12 WEDGE 24 x24 n 12 in. o 6.5 lbs.

SFC-18 WEDGE 24 x24 n 18 in. 4 8 lbs.

TABLE 2 .. WPICAL REFLECTIVIry AT NORMAL INCIDENCE, dB

Frequency in

GHz h 1 o 10 '18 36 50

SFC-6 WEDGE 30 40 45 45 45

SFC-8 WEDGE 30 ?6 45 47 47 47 47

SFC-12 WEDGE 35 J/ 45 47 47 47 47

SFC-18 WEDGE 30 .E 45 47 47 47 47 47

The information in this technical bulletin, although believed to be accurate, is not to be taken as a warranty for which Cuming Corporation assumes legal responsibility, nor as permission or recommendation to practice any patented invention without license; it is offered for verification by the customer, who must make the finaljudgement of suitability for any application.

Document Control No. N-1 5-000-01 26-4 2119197 page 2 of 2 tI cuMrNG MrcRowAVE f^l CORPORATION TECHNICAL DATA

230 BODWELL STREET AVON, MA 02322 (800) 432-6464 (508) 580-2660 FAX (508) 584-2309

TECHNICAL BULLETIN 390.1 O

C-RAM SFC-WALKWAY

C-RAM SFC-WALKWAY is a series of high performance broadbanded RF absorbers, fabricated from standard C-RAM SFC pyramidal absorber. The SFC absorber is fit with a low density polystyrene foam matching section to square the piece off, and the sides and top of the block are fit with a half inch (13 mm)thick sheeting of fire retardant polyvinyl chloride (PVC) rigid foam.

Walkway absorber provides an effective access path for servicing the transmit and receive areas of an anechoic chamber.

TYPICAL PROPERTIES

Reflectivity performance of a walkway is degraded from that of the SFC absorber comprising it, due to reflections from the PVC skin. The degradation becomes more significant with increasing frequency; below 1 GHz, the degradation is small, at 10 GHz, reflectivity is limited to about 25 dB, in mm-wave applications, other methods of accessing equipment should be considered, such as removing and replacing absorber before beginning testing.

Weight of a walkway piece is approximately 20- 25o/o heavier than ihe corresponding piece of C-

RAM SFC.

Height of a waikway section is 3 inches (75

mm) higher than the height of the C-RAM SFC grade from which it is made.

Color: Top and side surfaces are a textured olive green color. The black base of the SFC absorber is exposed on the bottom.

AVAILABILITY

C-RAM SFC WALKWAY can be made from any grade of the standard SFC absorber, but SFC- 24 is the largest standard size.

Pieces are generally 24 in x 48 in (610 x 1220 mm), or 24 in x24 in (610 x 610 mm). Other custom sizes can be made, as well as steps, ramps, and cutouts for pedestals.

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METHOD OF APPLICATION

Walkway absorber is simply laid in place on the floor of the chamber. As its performance is less than that of the corresponding grade of C-RAM SFC, the use of walkway should be minimized. lt should be kept near walls, always as far from the transmission path as possible, and never near the specular bounce points. lt is better to have two entries with short walkways than a long walkway servicing both the transmit and receive ends of the chamber.

For aesthetic purposes, since the walkway is 3 inches higher than the SFC grade fom which it is made, one may consider using a smaller grade than the surrounding SFC absorber. This will ensure the walkway is flush with or lower than the tips of the floor absorber.

The information in this technical bulletin, although believed to be accurate, is not to be taken as a warranty for which Cuming Corporation assumes legal responsibility, nor as permission or recommendation to practice any patented invention without license; it is offered for verification by the customer, who must make the finaljudgement of suitability for any application.

Document Control No. N-1 5-000-50734-0 2127197 page 2 of 2 f^JfI cuMrNG MrcRowAVE

CORPORATION TECHNICAL DATA

230 BODWELL STREET AVON, MA 02322 (800) 432-6464 (508) 580-2660 FAX (508) 584-2309

TECHNICAL BULLETIN 390-1 1

G-RAM CORNER BLOGK

LOSSY FOAM FOR FITTING ABSORBERS TO CHAMBER CORNERS

C-RAM Corner Block is a carbon loaded urethane foam materiai used to fit anechoic chamber materials, such as C-RAM SFC, into the corners and edges of the chamber.

These products meet all of the fire retardancy requirements of NRL Specification 8093.

TYPICAL PROPERTIES

C-RAM Corner Block is made of the same material as the pyramidal absorber it is being used with. lt wiil have the same density and impedance as the C-RAM SFC foam.

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

C-RAM Corner Block is custom made to each anechoic chamber job, and is available in almost any dimension. Cuming Corporation engineers can help you specify materials for a chamber application, and can recommend specific configurations of corner blocks.

Generally, the block is as thick as the base of the absorber prece butted next to it, and as wide as the height of the absorber facing it. For example, a 3 in x 18 in x 24 in piecewould be used when blocking SFC-18's in a corner.

METHOD OF APPLICATION

C-RAM Corner Block is applied to chamber walls just as the C-RAM SFC pyramidal absorber would be. lt is generally bonded in place with a neoprene contact adhesive, or it can be supplied with Velcro pile backing to attach to strips of Velcro hook bonded to the walls.

Edges and corners of the chamber are generally blocked out first, then the C-RAM SFC pieces are fit from the floor up to the ceiling. Corner Block is readily cut with a sharp knife, or, preferable, using a bandsaw or electric carving knife.

The information in this technical bulletin, although believed to be accurate, is not to be taken as a warranty for which Cuming Corporation assumes legal responsibility, nor as permission or recommendation to practice any patented invention without license; it is offered for verification by the customer, who must make the final judgement of sultability for any application.

Document Control No. N-15-000-50733-0 2127197 page '1 of 1