Miniaturized Shinkansen Antenna for Overhead-Line Voltage Detection and Wireless Communication

The rooftop antenna of the leading car on the Tokaido Shinkansen, which is a high-speed railway line in Japan, has two functions; 1) detection of the overhead-line voltage in 60 Hz and 2) wireless communication in the VHF band. In this paper, we propose a miniaturized antenna configuration to reduce aerodynamic noise caused by the antenna. When the detection rod that detects the overhead-line voltage is shortened, the performance of overhead-line voltage detection deteriorates, but the deterioration is minimized by making the antenna substrate area as large as possible within the antenna radome. Moreover, in the VHF band, the wideband characteristic is attained and the antenna gain becomes higher than the conventional antenna by using a folded monopole structure and a parallel resonant circuit. The effectiveness of the proposed antenna is confirmed by simulations.