Abstract: A method of communicating between an interrogator (10) and at least a first and second transponder (12). The transponders (12)are separately located within a first and a second vehicle (20) travelling within a first and a second traffic lane, respectively. The method has the steps of providing a first and a second LF antenna (16) associated with and proximity to a first and a second traffic lane, respectively. From each of the first and second LF antennas (16) a continuous LF subcarrier is transmitted to serve as a clock signal for each antenna's associated transponder (12). Initially, a wake-up signal is sent by each of the LF antennas (16) to its associated transponder (12). Following the wake-up signal, a unique lane code is sent by each of the LF antennas (16) to its associated transponder (12). The transponder (12) stores its unique lane code in its memory (70).

Abstract: An antenna system for use in an Automatic Vehicle Identification (AVI) system 10 having a plurality of non-resonant antenna loops 14 which operate as a single loop antenna during a transmit cycle and individual antenna during a receive cycle. The antenna system includes individual antenna 14 each having amplifier 29 connected to a single source. A switch circuit selectively switches the system from a transmit to receive mode and from a receive to a transmit mode.

Abstract: Apparatus and method for producing a flexible antenna suitable to be incorporated in a badge or similar object. The antenna comprises electrical windings (28, 38) surrounding a flexible antenna core (26, 36). The antenna core (26, 36) is of a material having a high quality factor formed of a plurality of mutually insulated, longitudinally extending chains of magnetic soft material of high .mu.. According to one embodiment, a powder of small particles of a magnetic soft material of high .mu. is mixed with a synthetic resin so that a high saturation of magnetic material in the mixture is formed in a vacuum. The mixture is cured in a strong magnetic field so that the particles form chains (18A, 18B, 18C) of the particle parallel to the applied magnetic field.

Abstract: An antenna circuit to be used in conjunction with a chip transponder such that the antenna circuit serves for both the reception of interrogative signals intended for the transponder as well as for response signals that ape to be transmitted by the transponder. The antenna circuit has at least one magnetic circuit of high .mu. material, and is formed of ceramic core means, that have been built into a depression in a thick-walled surface intended to receive the chip transponder. This thick-walled surface may be of metal. The ceramic core means comprise at least a ceramic core resonator and half a ceramic core that functions as an antenna with its open side facing outward. In one aspect, the ceramic core resonator and the half ceramic core antenna are coupled by means of one or more secondary coils of the closed ceramic core, which also form the coils of the half ceramic core antenna. In another aspect, the secondary coil forms a resonating circuit with at least one capacitive element in series.

Abstract: A method of communicating between an interrogator (10) and at least a first and second transponder (12). The transponders (12) are separately located within a first and a second vehicle (20) travelling within a first and a second traffic lane, respectively. The method has the steps of providing a first and a second LF antenna (16) associated with and proximity to a first and a second traffic lane, respectively. From each of the first and second LF antennas (16) a continuous LF subcarrier is transmitted to serve as a clock signal for each antenna's associated transponder (12). Initially, a wake-up signal is sent by each of the LF antennas (16) to its associated transponder (12). Following the wake-up signal, a unique lane code is sent by each of the LF antennas (16) to its associated transponder (12). The transponder (12) stores its unique lane code in its memory (70).

Abstract: A novel antenna system disposed around a conveyor belt for the interrogation of objects passing through the antenna which overcomes centralized dead zone problems is disclosed. A frame antenna which is disposed around the conveyor belt achieves the interrogation and a separate reading antenna, which is disposed hingedly from the top of the frame antenna performs the reception.

Abstract: A novel antenna system disposed around a conveyor belt for the interrogation of objects passing through the antenna which overcomes centralized dead zone problems is disclosed. A frame antenna is disposed around a conveyor belt and is tilted to form, for example, a 30 deg. angle with the vertical longitudinal plane of the conveyor belt, which is perpendicular to the horizontal plane within which the conveyor belt lies, and a 30 deg. angle with the transverse axis of the conveyor belt. In this way, a "dead-zone" free read area is formed to facilitate the read of a transponder oriented in any manner as it moves along the conveyor belt.

Abstract: Where a signal is to be sent to a transponder passing by an interrogation station, and a signal is to be received back from the device, the station should include one antenna for sending, one or more separate antennas for receiving, and a circuit including a transmit portion, one or more receive portions, and a transmit-receive switch portion.