Compact low profile UHF switched-beam antenna for advanced tyre monitoring systems

Advanced tyre monitoring systems are based on small sensor units directly embedded into the tyre rubber. In contrast to conventional tyre monitoring systems, more data like vibration information and slip angle are collected at this exposed position, so vehicular safety systems can be further improved. Powering of and communication with these sensor units, could be done with UHF radio frequency identification technology. In this contribution we propose a novel compact switched-beam antenna suitable for UHF frequencies. When mounted below the body floor pan of a vehicle, its directivity of 6 dB and the possibility to switch the main beam direction in 90? steps enables selection of a specific tyre for communication. Finally, we present measurements of the assembled antenna performed in an anechoic chamber.