Advanced RF Absorption for EMI Control, RCS Reduction and PIM Mitigation
When radio frequency (RF) sources are located within shielded cavities or confined enclosures, electromagnetic energy can resonate, creating unwanted interference, signal degradation and crosstalk between adjacent components. These resonances can compromise performance in electronic systems, antenna structures and RF enclosures.
C-RAM® microwave absorbers are engineered to address these challenges by attenuating resonant energy, suppressing surface currents and reducing reflections across a wide range of frequencies. Designed for demanding environments, C-RAM materials provide reliable RF absorption while maintaining flexibility, durability‑ and ease of integration.
Why Use C-RAM Microwave Absorbers?
- Attenuates cavity resonances and unwanted RF energy
- Reduces electromagnetic interference (EMI) and crosstalk
- Suppresses surface currents on conductive structures
- Improves antenna performance and radiation patterns
- Supports radar cross section (RCS) reduction
- The magnetically loaded elastomeric absorbers are non-conductive and appropriate for placement directly over circuitry
Broadband magnetic absorber families such as C-RAM GDSS, GDX, RGDS and others provide RF designers with proven solutions for EMI‑mitigation in aerospace, defense, communications and industrial applications.
Material Construction & Installation Options
Cuming Microwave supplies RF absorbers in standard sheet stock or custom-cut configurations to meet specific application requirements.
- Available with pressure-sensitive adhesive (PSA) backing for peel-and-stick installation
- Strong adhesive systems recommended for high-temperature, vibration, or harsh environmental conditions
- Offered in multiple binder systems and different fillers optimized by frequency band and application
Product Portfolio Overview:
Magnetically loaded RF absorbers:
C-RAM FLX series thin, flexible, resonant absorber
C-RAM FLX is a family of flexible microwave absorber sheet materials designed to absorb up to 99% of incident RF energy at specified design frequencies ranging from 1 to 35 GHz.
Key Features:
- Thin construction with wide operating temperature range
- Conforms easily to complex geometries
- Bonds readily to metallic and composite substrates
- Ideal for aircraft on board applications, ship masts, nose cones, housing and RCS reduction applications
C‑RAM FLX800‑ (800–900 MHz Cellular Band)
- Magnetically lossy silicone absorber, resonant around 850 MHz when backed by a conductive surface
- Effective for damping cavity resonances and reducing reflections in enclosed devices and test enclosures
- C-RAM FLX product family is available in silicone and urethane binders
High-loss silicone rubber sheet absorbers
C‑RAM GDSS
A thin, magnetically loaded silicone absorber with high microwave loss from 4 to 35 GHz.
Applications include:
- RF surface current attenuation
- Antenna pattern modification
- Lowering cavity Q
- Transmission line attenuation
- RCS modification
GDSS is flexible, die-cuttable, electrically non-conductive
C-RAM FDSS
Optimized for lower-frequency performance, C-RAM FDSS provides high magnetic loss between 300 MHz and 3 GHz.
- Similar construction to GDSS
- Excellent attenuation in VHF and UHF ranges
- Flexible and conformable for curved surfaces
Thicker grades are recommended for increased attenuation at lower frequencies.
Broadband Magnetic Absorber Solutions
C‑RAM FFS‑125
- Absorbs approximately 10 dB of RF energy from 2 to 12 GHz
- Effective over a wide range of incidence angles
- Ideal for large-area RCS reduction and structural integration
C-RAM FF‑2
- Ferrite-filled silicone absorber with high loss from 500 MHz to 10 GHz
- Effective up to X‑band
- Recommended for applications requiring UHF and higher-frequency absorption in a single material
C-RAM FGMM
- Broadband absorber providing approximately –10 dB attenuation from 4 to 10 GHz
- Suitable for aerospace, maritime and enclosure applications
Surface wave suppression & transmission line absorbers
C-RAM GDX
- High magnetic loss absorber covering 1 to 18 GHz
- Suppresses surface currents on metal structures
- Available in silicone or urethane elastomers
C‑RAM RGD‑S
A flexible silicone rubber absorber developed for terminations, loads, and attenuators in RF transmission systems.
- Grades available: –117, –124, –192 (increasing loss)
- Used in waveguides, coaxial lines, microstrip circuits and cavities
- Easy to die-cut or waterjet cut and thermally conductivity
- Withstands temperature cycling and harsh environments
- Carbon loaded foam absorbers
C-RAM MT
- Available in multiple grades to accommodate different frequency bands
- Isolation by insertion loss
- Eliminate cross talk
- Reduce cavity resonance
C-RAM LF
- Available in multiple grades to accommodate different frequency bands
- Reduce RF reflection
- Reduce Radar cross section (RCS)
C-RAM PIM-465 & PIM-645 Passive Intermodulation (PIM) Reduction
As wireless networks evolve to support higher data throughput, Passive Intermodulation (PIM) has become a critical system limitation. When multiple frequencies share the same RF path, even passive components exhibit non-linear behavior—producing intermodulation products that degrade network performance.
Sources of PIM can include:
- Antennas and RF hardware
- Nearby metal structures (fences, roof flashing, mounts)
- Mechanical joints and surface contacts
Cuming Microwave provides PIM mitigation solutions through:
- Sheet absorbers for isolation between antennas
- Reflectivity reduction materials for metal surfaces near RF paths
These solutions help network operators maximize bandwidth efficiency, signal integrity and quality of service (QoS).
RF Sheet Absorbers for free space applications
Cuming Microwave manufactures a complete line of flat sheet absorbers, pyramidal absorbers, convoluted absorbers and walkway absorbers suitable for:
- Free-space RF absorption
- Anechoic chamber lining
- Antenna pattern modification
- Broadband reflection suppression
Materials are available in weather-wrapped, coated, or flame-retardant versions, including UL94 HBF-compliant formulations.
