Plessey Semiconductors Limited

Peter P Blunden

David A Williams

Paul A Tyson

Stephen W Redfern

A Doppler microwave sensor for a vehicle alarm employs a mixer stage and a signal-processing stage on a printed circuit board, the printed circuit board having a ground plane containing a slot antenna which is coupled to the mixer stage. The ground plane is electrically connected to an electrically conductive enclosure which is disposed behind the slot antenna and encloses the component parts of the mixer and signal-processing stages. A dielectric lens may be placed over the slot antenna to provide a transmission beam pattern which is configured to the vehicle in which the sensor is to be used. In a preferred embodiment, the mixer stage is based arounda self-oscillating mixer arrangement in which the active element is a bipolar transistor and a single antenna is employed both to transmit the oscillator signal and to receive the Doppler-shifted return signal.

Doppler microwave sensor

A transponder tag operative in the UHF range and including a substrate of dielectric material having formed on one side a conductive surface providing a ground plane and a dipole antenna, a slot line within the ground plane forming a balanced antenna feeder and leading to the center of the dipole antenna, and the substrate having mounted on the side of the substrate opposite to the one side a transmission line feeder positioned for electromagnetic coupling with the slot line, the transmission line feeder being coupled to transceiver circuit and processing circuit mounted on the opposite side for performing a transponding function.

Growing community of inventors

Lincolnshire, United Kingdom

Peter P Blunden