High frequency and microwave absorber

EMI Absorber materials are used for electromagnetic insulation and electromagnetic emission absorption by Joule effect.

Several EMI absorber materials are available: wide range absorption foam, absorber or elastomer base absorbers with low thickness and frequency tuned.

Depending on the application, the frequency absorbers can be integrated outside or inside of an electronical equipment.

All of our absorbers are RoHS and REACH compliant.

Origin of the EMI and RFI problems that can be solved with EMI and RFI absorbers

There are two major reasons causing electromagnetic and radio-frequency interference:

1) Miniaturization and lack of space in the electronic assembly

The proximity between the electrical components increase the risk of perturbation between them. It is increased by the the miniaturization of the PCB and multi-board assemblies.

EM and RF absorbers can be stuck directly on the noise source or to protect the sensitive components (as sensors or antenna).

2) Radiation and electromagnetic noise transmitted by the cables

An electromagnetic noise might be generated by a high-frequency modules such as optical head in a compact disk or the FPC connector in the notebook.

To absorb the noise transiting in the cable, the absorber can be wrapped around the cable.

Why to use a frequency absorber sheet?

The absorber sheet is an efficient way to absorb electromagnetic waves and then to reduce electromagnetic noise. It is a way to quickly reduce EMI and RF issue to reduce time-to-market.

The field of application is wide. This kind of absorbers are integrated in digital product like digital cameras, mobile phones, notebook, PC Microprocessors and ICs, LCD panels and LNB.

These aborbers are also used for RFID projects (125kHz, 13,56MHz and 800-900MHz) to reduce interference with a metallic environment.

Frequency ranges of RF and electromagnetic absorbers, from RFID applications to hyper-frequencies:

Our range products are specifically offered for:

• LF (Low frequencies) : 30 to 300 kHz (RFID 125kHz, Wireless charge, induction)
• HF (High Frequencies) : 3 to 30 MHz (RFID 13,56MHz, NFC)
• VHF (Very High Frequencies) : 30 to 300 MHz (radio)
• UHF (Ultra High Frequencies) : 300 to 1 000 MHz (RFID 800-900MHz, Lora, Sigfox, telecom like 5G 600 to 700 MHz)
• SHF (Super High Frequencies) : 3 to 30 GHz (Telecom 5G sytems 2.5/3.4GHz and 3.8/4.5GHz also 28 to 39GHz, Wifi application 2.4-2.5GHz and 5GHz)
• Including the following bands : L (1 to 2GHz), S (2 to 4GHz), C (4 to 8 GHz), X (8 to 12 GHz), Ku (12 to 18GHz), K (18 to 27 GHz) and Ka (27 to 40 GHz)

Then :

• V Band : 40 to 75 GHz

• W Band : 75 to 110 GHz

• mm Band : 110 to 30 GHz

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For SHF and higher frequencies absorption, it is better to choose a full metallic part for electromagnetic shielding.

Depending on the absorption level required, the absorber can be really thin(0,1mm). The absorber can be cut and packaged in reel for automatization.

We support you to choose the best EMI absorber for your application.

How to choose the best absorber for radio-frequencies and electromagnetic fields:

Ask yourself the following questions:

• Where will be applied the absorber?
• For a Chamber (like anechoic chamber), you should use pyramidal foam
• For a test box, you should use a mix of flat foam, pyramidal foam and rubber absorber
• For integration inside an electronic device, you should prefer rubber absorber and/or flat foam absorber

• What is/are the major frequencies to be absorbed?
• What is the required absorbing rate (-dB)?
• Do you have space limitation?

Send us the answer using the contact form or the chat and we will suggest the best material for your application :)

What are the different kind of absorbers we propose?

Rubber Absorber for Hyper-frequencies and Microwaves precise band absorption : COHTR and CORTS Absorber

COHTR and CORTS Microwave Rubber Absorber is a serie of relative width band microwave absorbers which, typically, absorb -5dB ~ -25dB of normally incident energy for frequencies between 10MHz ~ 77GHz.

Based on the tuned frequency, COHTR/CORTS microwave rubber absorber is designed with thickness in the range of 0.1mm up to 4mm.

We also provide custom microwave absorbers, following your specifications (frequency, absorbing rate, thickness, etc).

COHTR and CORTS series are efficient to solve the EMI/RFI/EMC problem for electronic/ electric product, notebook, computer , electronic device ,wireless communication device , and even new-generation ultra-thin or mini-portable computer/PDA, digital camera, RFID, NFC, IEEE.801.a/b/ac/g/n product, wireless charging device, 5G mobile device, millimeter wave device, electric medical device...etc.

The product can be provided in sheet or in roll, and also can be pre-cutting to the desired shape.

The maximum temperature resistance is -40°C to +120 °C (on a short period of time, 10 min max, we would recommend +90°C max for longer periods).

Flat Foam Absorber for Hyper-frequencies and Microwaves large band absorption : FFTF(single layer) and FFTM(Multi-Layer)

FFTF(single layer EMI absorbing foam) and FFTM(multi-layer EMI absorbing foam) are a series of solid, flat type foam absorbing materials made from carbon loaded polyurethane foam. these microwave absorbers are mainly used inside electronic equipment, in shielding box, and to protect antennas and radars.

This kind of foam microwave absorber are available with different thickness. A higher thickness offers higher absorption level. The normal front surface color can be with/ or without blue-gray painting. The FFTF and FFTM microwave absorber should be installed on a metal surface to ensure the absorbing function. These hyper-frequency absorbers can also be delivered with an aluminium foil to ensure the reflection of the electromagnetic wave through the foam absorber.

The recommended operating temperature is -30°C to 90 °C maximum.

FFTF EMI and RF absorbing foam (single layer) specifications (more detailed specifications and absorbing curve on demand)

• FFTF-03 (thickness : 0.3cm) for absorption of frequencies higher than 8GHz, up to -10dB
• FFTF-04 (thickness : 0.4cm) for absorption of frequencies higher than 6GHz, up to -10dB
• FFTF-05 (thickness : 0.5cm) for absorption of frequencies higher than 6GHz, up to -10dB
• FFTF-06 (thickness : 0.6cm) for absorption of frequencies higher than 3GHz, up to -10dB
• FFTF-10C (thickness : 1.0cm) for absorption of frequencies higher than 3GHz, up to -15dB
• FFTF-15C (thickness : 1.5cm) for absorption of frequencies higher than 2GHz, up to -20dB
• FFTF-20 (thickness : 2.0cm) for absorption of frequencies higher than 2GHz, up to -20dB
• FFTF-30 (thickness : 3.0cm) for absorption of frequencies higher than 2GHz, up to -25dB

FFTM EMI and RF absorbing foam (multi layer) specifications (more detailed specifications and absorbing curve on demand)

• FFTM-15 (thickness : 1.5cm) for absorption of frequencies higher than 3GHz, up to -15dB
• FFTM-20 (thickness : 2.0cm) for absorption of frequencies higher than 2.5GHz, up to -20dB
• FFTM-25 (thickness : 2.5cm) for absorption of frequencies higher than 2.5GHz, up to -20dB
• FFTM-30 (thickness : 3.0cm) for absorption of frequencies higher than 2GHz, up to -25dB
• FFTM-60 (thickness : 6.0cm) for absorption of frequencies higher than 1GHz, up to -30dB

These foams for EMI and RF absorption are mainly provided in 60cm x 60cm. These absorbers can be cut following your drawings and specifications.

Pyramidal Foam Absorber for Hyper-frequencies and Microwaves large band absorption : FFTA

FFTA is a series of solid, pyramidal shaped absorbing foams made from carbon loaded polyurethane foam. It provides the highest broad band, from 80MHz to 60GHz, performance at both normal incidence and wide incidence angles of all know microwave absorbers. While primarily designed for low forward scatter, it offers favorable back scatter properties as well. It is thus well suited for use in all regions of anechoic chambers, or for covering test equipment within anechoic chambers. FFTA microwave absorber foam is available in a variety of thickness. The chamber designer has the opportunity to choose appropriate versions for specific requirements. The materials are normally provided in 60cm×60cm with adhesive. These absorbers can be cut following your specifications and design.

Especially the FFTA-36 and FFTA-50 foam absorbers are recommended for use in high quality microwave antenna or RCS test ranges. These foam EMI and RF absorbers are also used in semi-anechoic chambers which have to meet the 4dB volumetric NSA requirements from 80 MHz and in which a superior performance at microwave frequencies is required.

If the space is limited, the FFTA foam EMI absorber can be provided as hybrid type for low frequency absorbing.

FFTA EMI and RF pyramidal absorbing foam specifications (more detailed specifications and absorbing curve on demand)

• FFTA-1 (thickness : 1") for absorption of frequencies from K band to L band, up to -25dB
• FFTA-3 (thickness : 3") for absorption of frequencies from K band to L band, up to -50dB
• FFTA-5 (thickness : 5") for absorption of frequencies from K band to L band, up to -50dB
• FFTA-8 (thickness : 8") for absorption of frequencies from K band to 500MHz, up to -50dB
• FFTA-12 (thickness : 12") for absorption of frequencies from K band to 500MHz, up to -50dB
• FFTA-18 (thickness : 18") for absorption of frequencies from K band to 350MHz, up to -50dB
• FFTA-24 (thickness : 24") for absorption of frequencies from K band to 250MHz, up to -50dB
• FFTA-36 (thickness : 36") for absorption of frequencies from K band to 250MHz, up to -50dB
• FFTA-48 (thickness : 48") for absorption of frequencies from K band to 250MHz, up to -50dB
• FFTA-50 (thickness : 50") for absorption of frequencies from K band to 250MHz, up to -50dB

What is the next step for your project with Electromagnetic and Radio-frequencies Absorber?

We would be happy to help you to choose and to adapt the EMI and RFI absorbers for your project.

Send a message using the contact form or use the chat. We are here to bring you further ! :)