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Low-Frequency Absorbers
Magnetically-Loaded Absorption.
For Frequencies Below 1 GHz.
LOW-FREQUENCY RF ABSORBER FAMILY
Below roughly 1 GHz, wavelengths get long enough that carbon-loaded foam absorbers lose efficiency — you’d need impractical material thickness to hit meaningful attenuation. MAST’s low-frequency absorbers use magnetic loading instead of dielectric loading, absorbing RF energy through magnetic loss mechanisms and delivering usable attenuation in the VHF and UHF bands where standard foam falls short.
Low-Frequency
Product Family
30 MHz – 2 GHz
Coverage [⚑]
Magnetic
Loading Mechanism
AS9100D
Quality Certified
Low-Frequency RF Absorption
Where Wavelengths Get Long — Absorption Needs a Different Mechanism.
At 1 GHz, a wavelength in free space is about 30 cm. Drop to 100 MHz and it stretches to 3 meters. That length change is why carbon-loaded foam absorbers get impractical below 1 GHz — the material would need to be tens of centimeters thick to deliver useful attenuation.
MAST’s low-frequency absorbers solve this by changing the absorption mechanism — magnetic loading (ferrite or iron powder) absorbs RF energy via magnetic loss rather than dielectric loss, delivering useful attenuation at manageable thicknesses across the VHF and UHF bands.
TYPICAL APPLICATIONS
Low-Frequency
Different Physics
Magnetic Loss — Not Dielectric Loss
Magnetically-loaded formulations absorb via ferromagnetic resonance rather than resistive dissipation, working where wavelengths get too long for carbon loading
The Absorption Mechanism
Two Ways to Absorb RF. One Works Below 1 GHz.
The Other Doesn’t.
Standard Foam Absorbers
Dielectric Loss
Carbon-loaded — Efficient above ~1 GHz
Carbon-loaded polymer foams absorb RF energy by converting it to heat through resistive dissipation in the conductive carbon network. Efficiency scales with material thickness relative to wavelength — practical above roughly 1 GHz where wavelengths are short enough that reasonable material thicknesses deliver useful attenuation.
Effective Range
~1 GHz and Above
Loading Material
Carbon
Absorption Mode
Resistive / Dielectric
Material Density
Low (Lightweight Foam)
Low-Frequency Absorbers
Magnetic Loss
Magnetically-loaded — Effective below ~1 GHz
Magnetically-loaded materials absorb RF energy through ferromagnetic resonance — the alternating magnetic field of the incident wave drives the material’s magnetic dipoles, dissipating energy as heat via hysteresis loss. This mechanism works efficiently in the VHF and UHF bands where dielectric loss materials would need impractical thickness.
Effective Range
30 MHz – 2 GHz [⚑]
Loading Material
Iron / Ferrite
Absorption Mode
Ferromagnetic Resonance
Material Density
Higher (Magnetic Loading)
Common Applications
Where Low-Frequency Absorbers Get Put to Work.
Applications typically fall into three categories — anechoic chamber treatment, RCS reduction at long wavelengths, and EMI mitigation on cables, arrays, and enclosures.
01
EMC Test Chamber Wall Treatment
Anechoic chamber walls for EMC compliance testing across 30 MHz – 1 GHz, where standard pyramidal foam absorbers can’t deliver enough attenuation at the low end without impractical size.
02
VHF/UHF Radar Cross-Section Reduction
Radar-absorbing treatment for platforms exposed to long-wavelength radar systems — where dielectric absorbers would require thickness incompatible with airframe or vehicle envelope constraints.
03
Cable & Wire Harness EMI Suppression
Wrapped or clipped ferrite-loaded absorbers on cable runs to attenuate common-mode conducted emissions and reduce coupling between adjacent conductors at low frequencies.
04
Dense Antenna Array Isolation
Reducing coupling between closely-spaced antenna elements at VHF and UHF bands where element spacing is often much less than one wavelength.
05
Low-Frequency EMC Qualification
Attenuating VHF-band emissions inside enclosures during pre-compliance testing where standard high-frequency absorbers don’t move the needle.
06
Sub-6 GHz Wireless Infrastructure
Interference mitigation in sub-6 GHz cellular, public safety, and industrial wireless systems where low-frequency absorber treatment complements higher-frequency solutions.
Performance & Test Methods
Performance Characterization — NRL Arch & Transmission Tunnel.
Low-frequency absorbers are characterized using the same industry-standard RF test methods as MAST’s higher-frequency product families, with test setup adapted to accommodate the longer wavelengths and larger sample sizes involved at VHF and UHF bands.
Available Configurations
Configurations Are Specified to the Application.
Low-frequency absorbers are engineered around the specific frequency target, mounting method, and installation envelope. Rather than a fixed SKU catalog, our engineering team specifies the right formulation, thickness, and form factor for each application.
Specification Inputs
01
Target Frequency Range
The band where attenuation is required — the mechanism selection (ferrite vs iron powder) depends on this.
02
Available Thickness
Installation envelope constraints. Low-frequency absorbers are typically thicker than carbon-loaded — space budget matters.
03
Mounting Method
Sheet, tile, cable wrap, or custom form. Adhesive backing and mechanical fastening options both available.
04
Environmental Envelope
Indoor / outdoor / temperature range / flammability requirements shape the polymer binder selection.
Configuration-specific performance data is provided during the engineering consultation. Custom formulations, dimensions, and mounting configurations available across the family.
Work With Our Engineers
Match the Mechanism to the Frequency Target.
Low-frequency absorbers require more upfront engineering than standard product selection — the mechanism, formulation, thickness, and mounting all need to be aligned with the frequency band, installation envelope, and performance target. Our engineering team walks through the specification with you and identifies the right configuration for your application.
Engineering Question
Working a problem below 1 GHz?
Share the target frequency band, the installation envelope, and the attenuation you need to hit — our engineering team will identify whether a magnetically-loaded absorber is the right fit and specify the configuration.
Related Products
Explore Adjacent
Product Families
The right absorber depends on where your frequency target sits and how the material integrates with your build. These families cover adjacent applications.
Suppress-n-Sink™
Component-Level EMI + Thermal
The lowest-frequency discrete part in the standard portfolio — 0.5 to 12 GHz coverage in a dual-function EMI + thermal interface material, useful when the low-frequency problem sits at the component itself.
MF2 Series
Lossy Foam Absorbers
Broadband foam coverage from 1 GHz upward — the right choice when the problem starts at 1 GHz and extends to higher bands, where dielectric loss materials become efficient.
MC10 Series
Absorber Compounds
Castable, sprayable, and dispensable compounds — including magnetically-loaded formulations for applications where a low-frequency absorber needs to be integrated during fabrication rather than mounted afterward.
