Techinfo
Technical Information
Radio Wave Absorbers
Kitagawa Industries’ electromagnetic EMI absorber sheets and radio wave absorbers are highly effective in absorbing and suppressing noise of electromagnetic waves. With double-sided tape, the products are easily applied and provide excellent workability. These days, they have become one of the vital components in noise suppression.
EMI Suppression Sheets
What are EMI absorber sheets?
EMI absorber sheets are EMC management products that blend a magnetic material with a flexible resin. In recent years, with the increase in speed of CPUs, etc., the noise frequency band has shifted to high frequencies.
However conventional ferrites and filters affect the signal waveforms, making it difficult to suppress frequency noise.
Our EMI absorber sheets can absorb and suppress nearby noise when attaching them in the vicinity of the source. In addition, since it has little effect on signal waveforms, it is effective for high-frequency noise.
Recently, the use of the sheets in RFID devices has been increasing. This is because the characteristics of the magnetic material of the sheets can be used to limit the deterioration of antenna efficiency due to mutual interference between antennas and the surrounding metals.
How to use EMI absorber sheets
Attach an EMI absorber sheet in the vicinity of noise sources.
Examples: Applying an EMI absorber sheet to a flexible printed circuit (FPC) in a mobile device to suppress unwanted radiation. The sheet is attached inside the enclosure of an electronic device to attenuate radio wave resonance and inner reflections.
Attach an EMI absorber sheet between an RFID equipment antenna and the nearby metal plate.
Example: An EMI absorber sheet is attached between the loop antenna of an electromagnetic induction reader-writer and the metal enclosure to reduce eddy-current loss due to the metal plate and improve the efficiency of the antenna.
Benefits of using EMI absorber sheets
Lossy effects of magnetic materials; the resonant frequency is shifted by adding the circuit constant of the sheet itself, thereby preventing unnecessary radiation in the near field; and effective in suppressing unintentional electromagnetic coupling; and suitable for noise suppression at high frequencies.
Differences between EMI absorber sheets & Radio wave absorbers
A radio wave absorber is a resonant-type absorber that uses a dielectric material. While EMI absorber sheets are for near field noise, radio wave absorbers are intended to attenuate far field noise in specific frequency bands. The dielectric loss of the EMI absorber sheet enables effective attenuation at a specific frequency. The sheet for GHZ bands is available on your request.
Kitagawa Industries offer a full range of noise suppression products for noise from near field to far field, as well as for wideband and narrow band applications.
Characteristics of EMI absorber sheets
・Excellent flexibility
・A variety of dimensional shapes can be requested.
・UL flammability rated products are available.
・Two types of magnetic fillers are available, ferrite and metal
・A wide range of lineups from low frequency (magnetic measures) to high frequency (76.5 GHz)
・We offer unique product groups, such as composite products with high-thermal conductivity and products specializing in flexibility etc.
Applications of EMI absorber sheets
・Absorbing radiant noise inside products (FPCs, high-speed operating ICs, etc.)
・Reduction of crosstalk during high-density mounting
・Static electricity countermeasures
・Reduction of resonance and inner reflections in enclosures
・Improved sensitivity of RFID antennas
・Reduction of magnetic field energy generated from power supply systems