Cuming Microwave Corporation is at the forefront of
innovative microwave absorber technology and materials for the RF Electromagnetic Interference, Radar Cross Section Reduction and Anechoic
Chamber markets. From dielectric, artificial dielectrics, radomes, RF
absorbers, and anechoic chambers for the international aerospace,
electronics, and defense industries. From thin resonant absorption
sheets to 12 foot pyramids to radar reflectors for mach speed aircraft;
from do-it-yourself anechoic test chambers to turnkey anechoic chambers.
Cuming Microwave is a ISO 9001 Certified
Cuming Flexible Flat Foam RF & Microwave Absorber
Available in 2 Weatherproof Versions
FLEXIBLE FOAM SHEET
BROADBAND MICROWAVE ABSORBER
600 MHz - 40 GHz
C-RAM LF is a series of lightweight, flexible,
broadband radar absorbers made from graded layers of lossy open-cell
plastic foam. It is designed to provide typically 20 dB of reflectivity
reduction in a frequency range dependent upon grade. The product is
flexible enough to
conform to moderately contoured surfaces. CRAM LF is useful for reducing
reflections in radar test ranges, inside radomes, around antennas, and
for modifying antenna radiation patterns.
It is also available in two weatherproof versions:
C-RAM LF-W is standard LF absorber wrapped in a thin weatherproof
fabric tarp. The coating on this tarp is polychloroprene. Color is olive
green. For severe weathering conditions, the product can be supplied
wrapped in a white colored hypalon tarp which will withstand long term
sun and rain exposure, but with a penalty of reduced reflectivity
C-RAM LF-HCN is standard LF absorber
wrapped in a thin weatherproof white Hypalon fabric tarp.
Standard product size for all grades of LF are a
flat panel 610 x 610 mm (24 x 24 in.).
Other dimensions are possible,
including larger parts formed by butt-joining sections together.
Range of use
above 18 GHz
above 7.5 GHz
above 3.5 GHz
above 2.5 GHz
above 1.3 GHz
above 0.6 GHz
Cuming Reticulated Foam Microwave Absorber
SP - Standard Performance
HP - High Performance
2 GHz - 40 GHz
C-RAM AR is a line of reticulated foam Radar
Absorbing sheet materials, comprised of urethane foam and a gradient
lossy coating C-RAM AR absorbs microwave
energy across a wide range of frequencies. Typically the thicker the
material the lower in frequency C-RAM AR will attenuate.
C-RAM AR has
proven to be ideal for lining shrouds of communications antennas for the
suppression of side lobes. It can also be used to cover fences to
separate adjacent antennas, and shield or isolate equipment. The
open-cell structure permits airflow freely through the absorber, also
when used outdoors rain will freely drain from the product.
Cuming Microwave Corporation offers two types of C-RAM
AR, our standard performance AR and high performance AR.
C-RAM AR is available in standard sizes of 24 x 24 in
(610 X 610mm) and 24 x48 in. (610 x 1200mm).
Other sizes are available.
Cuming Microwave can also supply parts cut to drawings. Consult the
factory for alternative sizes.
C-RAM MT is a series of flexible, lightweight lossy
plastic foam sheet materials. A very broad frequency range of dielectric
loss is achieved through carbon loading of the foam. C-RAM MT can be
used to lower the Q of cavities, attenuate surface currents,
absorb stray RF energy, isolate components, and plug areas of RF
It is a lossy load material; applications requiring a free space
reduction of reflectivity should be addressed with C-RAM LF.
C-RAM MT is available in several grades having varying
levels of carbon loading, hence varying loss tangents. Each grade is
available in a range of thickness’. The material is a soft foam and is easily cut with a sharp knife.
Corporation can also supply C-RAM MT with a peel-and-stick backing, and
can die-cut or machine parts to specifications.
INSERTION LOSS AND
ATTENUATION (C-RAM MT)
INSERTION LOSS. dB/cm (dB/inch)
ATTENUATION, dB/cm (dB/inch)
Insertion loss measurements include the effects of
surface reflections; the above values are close to, but
not exactly, linear with thickness. For example, a 1/4
inch thick piece has somewhat more than 1/4th as much
insertion loss as a one inch thick piece. Attenuation is a measure of loss within a homogeneous
material, and does not take into account any reflections
at interfaces. It is independent of thickness. This is
calculated, not a measured value.
Cuming Silicone Rubber Microwave Absorber Sheet
product sizes for both grades are flat sheets 12 x 12 in (305 x 305
mm), available in several standard thicknesses including: 0.030 in
(0.76 mm) 0.040 in (1.02 mm) 0.060 in (1.52 mm) 0.125 in (3.17
mm) 0.250 in (6.35 mm)
1.5 GHz - 10 GHz
C-RAM RGD-S is a filled silicone rubber microwave
absorber sheet material with a high magnetic loss. It is available in
three grades: -117, -124 and -192. The -192 grade has higher loading and
higher losses.C-RAM RGD-S is used for terminations, loads, and
attenuators in waveguides, coaxial lines, and microstrip circuits.
can also be used for lowering the Q of cavities and eliminating unwanted
resonances.C-RAM RGD-S is cut readily with a sharp knife, and can be
sawed, die cut, waterjet cut, or otherwise machined to complex shapes.
Since it is ferromagnetic, it is easily held in place during machining
with magnetic chucks.
It is flexible and can be bonded to contoured
surfaces.Because it is flexible, C-RAM RGD-S can withstand temperature
cycling when bonded to metals.
The material has good thermal
conductivity and can be used to dissipate heat, including that generated
by its own magnetic loss mechanism.
TYPICAL PROPERTIES Color: Grey
Flammability: non-flammable Specific Gravity: 4.0 Thermal
Expansion per ºC: 6 x 10-5 Thermal Conductivity: .0021
cal-cm/sec-cm2-ºC 6.0 BTU-in/hr-ft2-oF Service Temperature: -55 to
+200° C (-65 to +400°F) Hardness, Shore A: 75 Water Absorption,
24 hrs: <0.1% Volume Resistivity, ohm-cm: >1010 Dielectric
Strength, kV/mm: >400 (>100 V/mil) Relative Impedance (Z/Zo):
0.3 for -117 0.4 for -124
0.6 for -192
-117 (Z/Zₒ 0.3)
-124 (Z/Zₒ 0.4)
-192 (Z/Zₒ 0.6)
Note: attenuation is a measure of the
absorption of RF energy within the material, and is not
the same as insertion loss, which includes reflected
energy at the air-material interface
Wave Absorber Sheet
High Frequency Radar Absorber
product sizes for all three grades are flat sheets 12 x 12 in (305 x 305
mm) and 24 x 24 in (610 x 610 mm), available inseveral standard thicknesses including:
0.040 in (1 mm)
0.125 in (3.17
0.250 in (6.35 mm)
0.50 in (12.7 mm)
18 GHz - 110 GHz
Cuming Microwave offers various materials that provide
excellent absorption at frequencies from 18 GHz to 110 GHz.
The C-RAM MMW absorbers include plastic foam sheet and
elastomeric-based materials that have been characterized for peak
performance across a wide range of frequencies.
C-RAM MMW has proven to be ideal for side lobe
suppression of communication antennas, used to separate adjacent
antennas, shield or isolate equipment and Anechoic chamber applications.
The reflectivity of C-RAM MMW varies as a function of
thickness and frequency. Standard sheet size is 24”x24” for foam and
12”x12” for elastomer in thicknesses shown in the chart below.
Non-standard thickness and sizes are available on
TYPICAL PERFORMANCE OF
C-RAM MMW-1 LIGHTWEIGHT FOAM Design Note: (AR)
Thickness Frequency Reflectivity
0.50” 26 to 110 GHz >20dB 0.25” 70 to 110 GHz >20dB
TYPICAL PHYSICAL PROPERTIES Color:
Black Density: 3.2kg/m² (0.65lb/ft²)
Temperature Range: -60 to 80°F (Standard Formula Flammable) note.
Frequency Reflectivity 0.125” 70 – 110 GHz >17 dB 0.250” 40 –
110 GHz >20 dB 0.500” 26 – 110 GHz >20 dB
PROPERTIES Color: Black Density (dependent upon grade): 0.06
to 0.13g/cm³ ( 4 to 8 lb/ft³) Service Temperature: -60°F to 180°F
TYPICAL PERFORMANCE OF C-RAM MMW-3
ELASTOMERIC Design Note:
Thickness Weight Frequency
Reflectivity 0.040” (1
mm) .5 lb/ft²
26 to 40 GHz -20dB 40 to 110 GHz >-15dB
TYPICAL PHYSICAL PROPERTIES Color: Grey Service Temperature: -80 to 275°F (-62 to
Jaumann Absorber Sheet
Flexible Radar Absorber
C-RAM LPJ is a series of lightweight, flexible,
weatherproof radar absorbers which can be used indoors, outdoors, or
wherever the material may be in contact with water, oil, or other
C-RAM LPJ is made of alternating layers of closed-cell
polyethylene foam and resistive layers. It is based on the Jaumann
principle of operation.
C-RAM LPJ is designed to provide typically 18 dB of
reflectivity reduction in a frequency range dependant on grade.
C-RAM LPJN is designed to provide typically 20 dB of
reflectivity reduction in the frequency range of 8-18 GHz.
2.5 GHz - 18 GHz
The radar absorber is useful for reducing
reflections from flat surfaces, columns, and structures such as bridges.
Its easy-to-clean surfaces and non-dusting behavior make it suitable for
The standard size of C-RAM LPJ is 24 x 24 in. Standard
thicknesses are noted in the chart below. Other thicknesses, shapes, and
sizes are available on a custom order basis. It can be easily cut to
special size or shape, and the edges do not require resealing. Sheets
are bonded together or to a reflecting surface with a contact adhesive.
Color: White Size: 24” x 24” standard Service
Temp.: -40°F to +180°F (LPJ) -40°F to +300°F (RCJ)