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US 9,721,200 B2Granted
Card with metal layer and an antenna
AssigneeCompoSecure, LLC
InventorsJohn Herslow, Michele Logan, David Finn
Life of this patent
Estimating the term…
Abstract
In a smart card having an antenna structure and a metal layer, an insulator layer is formed between the antenna structure and the metal layer to compensate for the attenuation due to the metal layer. The thickness of the insulator layer affects the capacitive coupling between the antenna structure and the metal layer and is selected to have a value which optimizes the transmission/reception of signals between the card and a card reader.
Claims16
A method for determining a preferred range of thickness for an insulator layer formed between an antenna structure and a metal layer comprising the steps of:
- forming said insulator layer between said antenna structure and said metal layer, with said insulator layer being in direct contact with said antenna structure and said metal layer;
- where said insulator layer exhibits capacitance coupling the antenna structure and the metal layer;
- and wherein the thickness of the insulator layer affects the value of the capacitance between said antenna structure and said metal layer;
- varying the thickness of the insulator layer over a range extending between a first, minimum, value and a second, higher, value for varying the capacitance exhibited between said antenna structure and said metal layer;
- transmitting RF signals to the combination of the antenna structure, the insulator layer and the metal layer for selected values of insulator thickness within said range;
- sensing the amplitude of the signals received at the antenna structure for said selected values of thickness of the insulator layer;
- and
- identifying the insulator thickness which results in the highest amplitude of signal being received at the antenna structure.
5 more elements
A smart card comprising:
- an insulator layer formed between a metal layer and an antenna structure;
- said insulator layer having first and second surfaces, said first surface being in direct contact with said antenna structure and said second surface being in direct contact with said metal layer;
- and said insulator layer exhibiting a coupling capacitance between said antenna structure and said metal layer whose value is a function of the thickness of the insulator layer;
- said metal layer tending to attenuate the amplitude of radio frequency signals received at the antenna structure;
- the thickness of the insulator layer being selected to have a value determined by analyzing the results obtained from testing corresponding structures by varying the insulator thickness which varies the value of the coupling capacitance and identifying for which value of insulator thickness best reception is obtained at the antenna structure;
- and
- the selected thickness of the insulator layer being such that the amplitude of the received signal at the antenna structure is maximized.
4 more elements
A method for forming a smart metal card comprising the steps of:
- forming a combination including an antenna structure and a metal layer with an insulator layer formed in direct contact between the antenna structure and the metal layer;
- wherein said metal layer tends to attenuate the amplitude of radio frequency signals received at the antenna structure;
- where said insulator layer exhibits capacitance coupling the antenna structure and the metal layer;
- and wherein the thickness of the insulator layer affects the value of capacitance between said antenna structure and said metal layer;
- and
- forming the insulator layer with a thickness selected to provide a quasi-resonant frequency response such that the amplitude of the signal received at the antenna structure is maximized;
- and
- wherein the value of said insulator thickness is obtained by testing a number N of different combinations, similar to said combination, in which the thickness of the insulator is varied and identifying which thickness provides the best reception to RF signals.
5 more elements
A method for making smart metal cards including the steps of:
- forming N test cards, where N is an integer greater than 1, each one of said N test cards including an insulator layer formed in direct contact between an antenna structure and a metal layer;
- where said insulator layer exhibits capacitance coupling the antenna structure and the metal layer;
- and wherein the thickness of the insulator layer controls to a great degree the value of capacitance between said antenna structure and said metal layer;
- and wherein the thickness of the insulator layer of the N test cards have different values;
- transmitting selected RF signals to each one of said N test cards;
- sensing the amplitude of the signals received at the antenna structure of each one of said N test cards;
- and
- identifying the test card having the highest amplitude of signal received at the antenna structure.
5 more elements
Dependencies are inferred from the claim text.