De-tuning tolerant loop antenna
| DWPI Title: RFID tag for using a detuning-tolerant loop antenna to output a radiated RFID tag signal, comprises a loop antenna operable to transmit or receive a radiated signal at the operational frequency both in a free space environment |
| Abstract: A loop antenna is described herein that is suitable for operation in free space or in proximity to a ground plane. The loop antenna comprises a looped conductive element with a gap formed therein and a tab extending toward the gap. A length of the tab of the loop antenna is selected such that a detuning loss of the loop antenna from operation in free space to operation in proximity to a ground plane is low. In an exemplary embodiment, the length of the tab is selected such that a reactance of the loop antenna in free space is within a threshold level of a reactance of the loop antenna when the antenna is in proximity to a ground plane. |
| Use: Radio frequency identification (RFID) tag for using a detuning-tolerant loop antenna to output a radiated RFID tag signal. |
| Advantage: The voltage reflection coefficient at the operational frequency is very small for the conventional loop antenna in free space, which allows an efficient operation in free space. The detuning loss is maintained within the desired loss threshold by matching a reactive portion of the impedance of the antenna in free space to a reactive portion of the impedance of the antenna when the antenna is in proximity to a ground plane. |
| Novelty: The RFID tag comprises a loop antenna (100) tuned for an operational frequency, and a looped conductive element (102) is formed to define a tab (114,116) that extends toward the gap (112). The tab having a length, and the loop antenna is operable to transmit or receive a radiated signal at the operational frequency both in a free space environment and within a threshold distance of a conductive surface. The loop antenna has a first reactance when the loop antenna is in free space, and the loop antenna has a second reactance when the loop antenna is within the threshold distance of the conductive surface. The loop antenna is arranged within the housing, and the tab of the looped conductive element is substantially parallel with the surface when the housing is affixed to a surface. |
| Filed: 9/11/2018 |
| Application Number: US16127577A |
| Tech ID: SD 14594.0 |
| This invention was made with Government support under Contract No. DE-NA0003525 awarded by the United States Department of Energy/National Nuclear Security Administration. The Government has certain rights in the invention. |
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