| The measure of a material¡¯s ability to store a charge when an electric field is applied, or its ¡°capacitance.¡± If a material has a high dielectric constant, it reflects more RF energy and detunes the antenna more, which makes it harder to tag. Examples of materials with a low dielectric constant are dry paper (2), plastics (most are between 2 and 4), and glass (between 5 and 10). Water¡¯s dielectric constant changes: At room temperature it is 80; near boiling it is 55; and when frozen it is 3.2. |
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