Emerson & Cuming Microwave Products Absorbers For RFID Portals

With the growing ubiquity of RFID applications, companies are finding it necessary to isolate reader antennas from each other to prevent interference. When multiple readers are operating in the same area, crosstalk can cause inaccurate results with 'no reads' and 'double reads'. Isolation becomes even more critical in 'listen before talk' atmospheres.

Emerson & Cuming Microwave Products offers several ECCOSORB® absorbers ideal for use in isolating RFID portals. There are two types of applications to be aware of which each require a different type of absorber.

Reflectivity absorbers such as ECCOSORB® AN reduce reflections off metal surfaces. This is sometimes necessary to eliminate reflections off large metallic objects in or near the read zone. AN-77 will give very good reflectivity (-10-12 dB or 90% absorption). For proper operation, AN material needs to have a metal backing. This is not an issue if it is to be applied to a smooth metal surface. For more complex surfaces, an integral ground plane can be included with the material.

Insertion loss absorbers such as ECCOSORB® LS provide high loss barriers to prevent direct signals from one point to another. These could be used for direct isolation of one portal or antenna from another. LS is a foam sheet available in a range of grades and thicknesses. We recommend LS-26 for RFID applications. Depending on the level of insertion loss required, the desired thickness should be 0.25" (-8 dB) , 0.5" (-12 dB), or 0.75" (-16 dB) .