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RF Absorber Materials

Panashield offers a wide range of RF absorber products. These materials are sometimes also referred to as Radar Absorber Material (RAM) or Microwave Absorber.

Materials available from Pansashield include:

RF Absorber Materials

Ferrite & Hybrid Absorbers

High Performance Broadband Pyramidal RF Absorber

This is the most widely used absorber product and is generally found in Anechoic Chambers and in Free Space Chambers used for Antenna Pattern Measurements (APM) and Radar Cross Section (RCS) measurements etc. Larger absorbers are also used in some EMC chambers.

Absorbers are manufactured from low density polyurethane foam impregnated with a dielectric 'lossy' solution. The pyramidal shape produces an impedance gradient which results in high performance / reflectivity levels in Anechoic Chambers at both normal and off-normal angles of incidence.

The absorber is treated to provide a finished product that meets the fire retardant requirements of NRL specification 8093 tests 1, 2 and 3, MS-8-21 tests 1,2 and 3 and other International specifications.

The absorber is usually spray finished with a coat of light blue paint although other colours are available on request.

The typical nominal size of Pyramidal RF Absorber ranges between 4 in. (105mm) and 72 in.(1830 mm). Base dimensions are 610x610 mm.  Please contact Panashield for full physical and performance data on our range of absorber materials.

Absorbers are installed in chambers using contact adhesive.  Velcro can also be used although this is usually limited to absorbers with a depth of 24"(610 mm). For very large depth absorbers a steel base can be factory installed on the absorber base and fixed to the chamber with a clip and rail system.

Truncated Pyramidal RF Absorber

This material is similar to the standard High Performance Broadband Pyramidal RF Absorber but the tips are removed to provide a truncated version. The truncated shape reduces overall depth of the absorber, saving space in chambers and tip breakage is eliminated providing a more rugged product.

The truncated pyramidal RF absorber was developed specifically for low frequency applications in particular for designing EMC test chambers for emissions and immunity testing to industrial and military specifications. Reflectivity an physical characteristics:

Weight

Absorber Depth

Reflectivity (MHz)
(kg)

(mm)

80 250 500 1000 10,000
7.7 510 -8dB -22dB -35dB -38dB <-40dB
15.9 760 -15dB -27dB -27dB -40dB <-40dB

A combination of both material sizes installed in an appropriate sized chamber will provide an EMC test facility for full compliance immunity testing to EN 61000-4-3 and pre-compliance emissions testing.

The RF absorber is normally spray finished with a coat of light blue paint. Other colours are available on request.

The absorber is treated to provide a finished product, which meet the fire retardant requirements of NRL specification 8093 tests 1,2 and 3, MS-8-21 tests 1,2 and 3 and other International specifications.

High Performance Wedge RF Absorber

This High Performance RF Absorber is wedge shaped and complements the conventional pyramidal shaped RF absorber. It is manufactured using the same material and processes.

The Wedge RF Absorber is designed primarily for use in chambers where RF energy is directed in a particular path such as energy propagation along a tapered chamber or in areas of the walls, floor and ceiling of a Free Space Chamber where the energy is directed to conventional pyramidal absorber on the back wall. Backscatter is significantly reduced or eliminated at these high angles of incidence.

The wedge absorber is produced with a base size of 610 mm x 610 mm and is available typically in the following depths:

152 mm, 203 mm, 305 mm and 457 mm

A feature of the Wedge RF Absorber is that its reflectivity performance at normal or near normal angles of incidence is similar or close to the standard RF absorber products.  However it’s wedge shape does make the product sensitive to polarisation. Consequently, the reflectivity values of Wedge RF absorber are 2 to 4 dB less than the equivalent depth Pyramidal RF Absorber.

Physical and performance characteristics are available on request from Panashield.

High Performance Convoluted RF Absorber

Convoluted RF absorber is manufactured from urethane foam loaded with carbon dielectric 'lossy' solution and treated to provide a fire retardant absorber meeting NRL specification 8093.

This high frequency absorber is installed in non-critical regions of Free Space Anechoic Chambers or very high frequency chambers. It may also be used for a variety of other application where it is necessary to reduce unwanted RF and radar reflections.

The front face of the absorber is convoluted, or rippled similar to an egg carton in appearance. The base size is 610 mm x 610 mm and is available in three depths

38 mm, 76 mm and 102mm.

Physical and performance characteristics are available on request from Panashield.

Convoluted RF Absorber is generally installed using contact adhesive but can also be supplied for installation with Velcro.

Corner Block RF Absorber

Corner Block RF Absorber is produced using the same materials and manufacturing processes as the other conventional RF Absorbers and like the other materials meets the fire retardant requirements of NRL 8093 test 1,2 and 3 etc.

This absorber material is generally used for positioning in the corners of chambers lined with Pyramidal and/or Wedge absorbers. The absorber is available in a range of thicknesses. The thickness is usually matched to the base thickness of the pyramidal or wedge material against which it is to be installed. The typical base size is 610 mm x 610 mm but this flat corner material can be provided to any base size for easy field installation. Where necessary the absorber can be easily cut with a sharp knife or blade

Corner Block RF Absorber is generally installed using contact adhesive but can also be supplied for installation with Velcro. It is generally supplied unfinished (black) but may be spray painted blue.

Walkway RF Absorber

Walkway RF Absorber is provided for installation in Free Space chambers where it is necessary for personnel to walk for example from the door to the antenna and or test object.

Conventional Pyramidal RF Absorber is in-filled with a dielectric material to provide a flat surface for walking.

Due to material content other than the pyramidal absorber used to produce Walkway RF Absorber the reflectivity of the absorber is reduced. The quantity of Walkway Absorber and positioning on the chamber floor can therefore be very important. Walkway absorber should be limited to the area leading from the door(s) entrance directly to the antenna and object under test at each end of the chamber. This is preferable to walkways along the length of the chamber. The walkway should not be placed on critical regions of the floor.

Where necessary it may be better to use conventional absorbers only and remove and replace them only as necessary.

The base size is generally 610 x 1220 mm and the height approximately 76 mm higher than the equivalent conventional Pyramidal RF Absorber.

Other RF Absorbers

Several other types of Absorbers are also available for example for high power, outside applications and clean rooms. Please contact Panashield for details.

FERRITE and HYBRID ABSORBERS

The majority of EMC Test Chambers are now designed and installed using ferrite tile absorbers and when testing will be performed above 1 GHz, which now also becoming an industry standard, a hybrid absorber is installed over the ferrite.

Ferrite Absorber

Ferrite absorber is produced as tiles of size 100 mm x 100 mm and thickness available between 6 mm to 6.7 mm. For ease of installation the ferrite tiles are factory glued to wood or steel panels of size 300 mm x 300 mm or 300 mm x 600 mm. When installed in Panashield’s modular shielded room these panels are screwed directly to the shielding panels.

Ferrite absorbers provide high performance at low frequency compared with pyramidal RF absorber, providing excellent absorption from 30 MHz to 1 GHz. They are very thin allowing chambers to be designed smaller than those previously designed using conventional pyramidal absorber. This can be important where available space within buildings is limited.

Hybrid Absorber

To extend the frequency range of chambers up to 18 or 40 GHz Panashield have two types of absorber, which are matched to the ferrite tile to produce a hybrid absorber.

HYB-NF Hybrid absorber

The most recent product development in this field, now available from Panashield is our HYB-NF hybrid absorber.  HYB-NF is a state of the art non-flammable, self-extinguishing hybrid absorber, manufactured from a fibrous composite material, impedance matched for installation over ferrite absorber tiles. The ferrite tile/ hybrid combination provides absorption for broadband testing over the frequency range 26 MHz to 40 GHz.

This new absorber has many advantages over conventional foam based hybrid absorbers.

  • High broadband performance.
  • Meets Class 10,000 Clean Room
  • Non-Flammable, Self-extinguishing Specifications
  • Non-Toxic Smoke Emitting 
  • Light Weight (6 ounces)
  • Meets specification JIS A 1322
  • Bright White Colour
  • Incombustibility of Thin Materials
  • Easily removable buildings
  • Can be attached to ferrite with Velcro™
  • Resistant to High Humidity Levels 
  • Short Depth (30cm up to 60cm)
  • HYB-NF is available in depths 305 mm, 457 mm and 610 mm

Normal Incidence Reflectivity for HYB-NF-12
when applied to Ferrite Tiles

30
MHz
100
MHz
300
MHz
1
GHz
3
GHz
5
GHz
10
GHz
18
GHz
40
GHz
-15
dB
-23
dB
-25
dB
-22
dB
-24
dB
-25
dB
-21
dB
-29
dB
-35
dB

Conventional Hybrid Absorber

As an alternative to the HYB-NF hybrid, Panashield also provide a hybrid absorber manufactured from a polyurethane foam and carefully designed and manufactured to ensure an impedance match with ferrite tiles. The absorber is treated to ensure it meets with the fire retardant requirements of NRL 8093 tests 1,2 and 3.

This absorber is supplied with a base size of 610 x 610 mm and is available in different depths and shapes:

  • 457 mm and 610 mm - wedge
  • 914 mm and 1220 mm - pyramidal

The absorber is sprayed with a coat of light blue paint. Other colours are available on request.

For More Information

Panashield, Inc.
185 West Norwalk Road #R
Norwalk, CT 06850
(203) 866-5888
help@panashield.com