Patent ID: 7446644

Claim:
An access control system, comprising: a key unit comprising an antenna and a transmitter configured to transmit a radio frequency (RF) signal over the antenna, the RF signal containing an identification (ID) code identifying the key unit; a plurality of lock units, each lock unit comprising: an antenna for receiving the RF signal from the key unit; and a reader coupled to the antenna for receiving the RF signal from the key unit, identifying the ID code contained in the RF signal, comparing the received ID code with a list of one or more authorized ID codes, and if the received ID code is included in the list of authorized ID codes, granting access to a secured resource; a first printed circuit board (PCB) having a reflector provided on a first side and a driven element provided on a second side opposite the first side; and a second PCB positioned adjacent to the first PCB between the first PCB and the direction from which the secured resource is capable of being accessed by the key unit and having a planar conductive layer (i.e. a “director”) provided on the side of the second PCB accessible by the key unit; wherein at least one of the lock units is configured to respond to RF signals in a directionally preferential basis; wherein the lock unit configured to respond to RF signals in the directionally preferred basis comprises an RF signal shield positioned on one side of the antenna; and wherein a first lock unit has a first activation range and a second lock unit has a second activation range different from the first activation range.