Emerson & Cuming Microwave Products, Inc.

Other

Mary M Osward

David A Gibbs

Michael P Carpenter

Paul F Dixon

A system and method for the use of ultra high frequency RFID tags in conjunction with metal substrates, as well as substrates used to contain liquid. Briefly, an RFID isolator comprised of a material with complex magnetic permeability, used either by itself, or in combination with dielectric isolator material, is interposed between the RFID tag and the substrate. Alternatively, a material possessing at least two distinct dielectric constants is interposed between the RFID tag and the substrate, such that there is a high dielectric constant at the interface with the substrate, and a low dielectric constant at the interface with the RFID tag. This material can be a single material having a dielectric constant gradient, or alternatively, two or more separate layers, each with a uniform but different dielectric constant, sandwiched together.

RFID tags

The present invention provides a system and method for optimizing the performance of 13.56 MHz frequency RFID tags in conjunction with metal substrates. Briefly, a thickness exists for each type of RFID isolator material at which the performance of a 13.56 MHz RFID tag is optimal when used with metal. Varying from this optimal value, in either the positive or negative direction adversely affects read distance. A method of determining this optimal thickness is disclosed, as well as an RFID tag or a substrate being used in conjunction with a material of this thickness.

RFID tags having improved read range

Disclosed is a lens of gradient dielectric constant and methods for the production of same. The lens includes an inner core comprising a cured or fused substantially homogenous blend of glass spheres, curable or fusible binder and, as needed to increase dielectric constant, a low-loss dielectric material. The inner core preferably has a dielectric constant of about 2.0, and an interstitial void volume (representing trapped air space between elements of the cured or fused material) of from about 30% to about 50%. The lens also includes an outer shell layer comprising a cured or fused substantially homogenous blend of hollow glass spheres and curable or fusible resin. The outer shell layer preferably has a dielectric constant of about 1.0, and an interstitial void volume of from about 30% to about 50%. In addition, the lens includes a minimum of one, and preferably two or more intermediate layers, the intermediate layers having a dielectric constant falling between 1 and 2. The intermediate layers are comprised of a cured substantially homogenous blend of glass spheres, resin and, as needed to increase dielectric constant, a low-loss dielectric material. As is the case with the inner core and outer shell layers, the intermediate layer(s) have an interstitial void volume of from about 30% to about 50%. Also disclosed are methods of production for lenses of the type described above.

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Holbrook, MA, United States of America

Mary M Osward