Research and Development Menu (Tap to Display Menu)
Material Performance Test
Material Specifications
The low-frequency magnetic field shielding sheet "EMSpanel" is structured to attenuate low-frequency magnetic fields by laminating conductive and magnetic materials. Since "MG Net" does not have shielding performance against low-frequency magnetic fields, EMSpanel was developed to protect pacemakers from electromagnetic interference over a wide frequency range [Figure 1]. It consists of a laminated structure of aluminum foil and magnetic film. The 5-layer type EMSpanel used in electromagnetic shielding garments for pacemaker users is only 0.7 mm thick, yet achieved a shielding effectiveness of approximately 60 dB in the low-frequency electromagnetic field range from 100 Hz to 300 kHz in shielding strength tests.
▲Figure 1: EMSpanel Structure
Electromagnetic Shielding Performance
Theoretical Formula for Electromagnetic Shielding Effect
The larger the value of S, the greater the electromagnetic shielding effect. Therefore, materials with a large δ value should be selected for electromagnetic shielding. The EMS pad uses a high-permeability magnetic sheet (120 μm thick).
Improved Shielding Effect by Layering Materials
The theoretical formula for the shielding effect S when materials are layered is shown below.
The larger the value of S, the greater the electromagnetic shielding effect. By layering shielding materials, the shielding performance is enhanced. EMSpanel consists of a five-layer structure of aluminum foil and high-permeability magnetic sheets.
Magnetic Shielding Strength Test
The shielding magnetic field strength was measured using the method shown below [Figure 2]. A tracking pulse is transmitted from a loop antenna and received by a loop antenna on the other side of the test material to measure the shielding strength.
▲Figure 2: Shielding Magnetic Field Strength Test Method
Figure 3 shows the test results of EMSpanel’s shielding magnetic field strength. Despite being only 0.7 mm thick, the 5-layer structure of aluminum foil and high-permeability magnetic sheet achieved a shielding effectiveness of up to 60 dB (99.9%) in low-frequency electromagnetic fields ranging from 100 Hz to 300 kHz. It has also been confirmed that low-frequency electromagnetic fields emitted by IH cooking heaters are strongest around 20 kHz to 30 kHz, and the shielding effect in this range was also confirmed to be 60 dB (99.9%).
▲Figure 3: Measured Data of Shielding Performance
(*Note: logarithmic scale of base 10, not uniform intervals)
Reference: *Latest Absorption and Shielding of Electromagnetic Waves*, Nikkei Technical Publishing
Basic Performance Tests for Electromagnetic Protection Garments