An advanced 2.45 GHz radio communication system for automatic passenger gates

A 2.45 GHz wireless card system for automatic passenger gates in train stations has already been reported [1]. The system uses three key technologies: a small-size dual port slot antenna for the wireless card, a modulation/demodulation scheme that facilitates stable data transmission between the transmitter and the card, and a co-channel allocation system with phase-locked transmitters for effective utilization of frequency resources in multiple gate operation. This paper describes an advanced version of the wireless card system that uses a circularly polarized shaped-beam three-patch antenna to realize a wider communication area between the transmitter and the moving card, and a non-phase locked co-channel allocation system for simpler construction of a multiple gate system