Ferrite tile is a square-shaped electromagnetic absorber tile made of sintered ferrite. It absorbs incident electromagnetic energy and converts it into heat through magnetic loss, thereby helping to reduce or eliminate electromagnetic wave reflections/suppress electromagnetic noise in various applications, such as anechoic chambers. Magnetic loss in ferrite occurs due to eddy current loss, natural resonance, domain-wall resonance, and exchange resonance when electromagnetic waves pass through the material. 

Ferrite tiles provide optimum performance in the 30 MHz to 1 GHz frequency range, with typical absorption levels between 10 dB and 25 dB. They come in various sizes, such as 100 x 100 mm and 600 x 600 mm, and thickness options like 0.8 mm, 4 mm, 6 mm, and others. These tiles can be mounted on walls and ceilings using screws or adhesive. They are compatible with concrete, exterior porcelain tiles, etc. The tiles come in solid, flexible, and panel formats. The ferrite tile panel is an assembled unit of multiple ferrite tiles.

Key benefits of the tiles include being more rugged, easy and quick to assemble, long lifespan, less susceptible to fire, humidity, and chemicals, and occupying less space inside an anechoic chamber (meaning allowing more test volume space).  However, one notable drawback is that air gaps between adjacent tiles can degrade absorption performance. The air gaps issue can be minimized by precisely machining all the sides of the tile during installation.  

Figure: Flexible ferrite tiles and its application shown

Extended Frequency Applications/testing: 

For high-frequency testing needs (>1 GHz), ferrite tiles can be mounted over a dielectric spacer of suitable thickness to create a double-layer or composite radio wave absorber, which offers enhanced performance and an extended frequency range.

Ferrite tile applications: 

• Reduces or eliminates reflections in anechoic chambers for EMC testing
• Suitable for normalized site attenuation in EMC chambers per ANSI C63.4, and for applications in accordance with CISPR 16-1-4 and IEC 61000-4-3
• It prevents TV ghosting caused by waves reflected off high-rise buildings. 
• Prevents radio communication disturbance
• Effective in a Dark box for mobile phone inspection
• Prevents UHF RFID-readers interference
• Prevents false images on the airborne radar.
• Very thin tiles are used for EMI absorption on ICs, CPUs, and bus drives running at high clock speeds.
• Flexible ferrite tile used for EMI suppression for IC.
• Used as a building material for EMI protection.