| 摘要 |
An apparatus, which may be a beacon, for communicating with a wireless device, the apparatus having a shrouded antenna arrangement 700 to form a detection zone. The shrouded antenna arrangement comprises an antenna 705 encased in shroud 710 which is made of a radio frequency absorbing material (RFAM). The RFAM shroud or shield may have a thickness profile that varies around the antenna with a reduced thickness in the forward direction (indicated by arrows). In this way the radiated field is attenuated in all directions other than the forward direction to establish a detection zone. The surface part 715 of the shroud may have a concave profile with a small convex portion 716 at the center. The wireless device may be a wireless mobile device having an identifier and may include a security tag such as an RFID or use Bluetooth (RTM) or Wifi (RTM) standards. The apparatus provides a system to monitor location or movement of people carrying a wireless device within the detection zone. |
