TABLE OF CONTENTS Yoshiyuki Chatani
In this chapter, the bullet train antenna system in Japan is introduced. In Section 9.2, an outline of the LCX (leaky coaxial cable) communication system of Japan's bullet train is described. In Section 9.3, the structure and principle of operation of the leaky coaxial cable is described, and two types of train antenna are shown.
Leaky coaxial cables are used for the train communication systems of Tokaido [Tokyo-Osaka (553 km)], Sanyou [Osaka-Fukuoka (624 km)], Tohoku [Tokyo-Hachinohe (632 km)], and Joetsu [Tokyo-Niigata (334 km)] Shinkansen [Japan Railways (JR) new bullet trains] [1 5]. They are coaxial cables whose outer conductors have slots radiating a part of the transmitted energy [6 9]. (An example is shown in Figure 9.1.) LCX cables were first developed for train communication systems in a tunnel for Tokaido and Sanyo Shinkansen. The advantages of LCX cable systems compared to radio communication systems were then realized. They offer more stable and better train communications compared to radio communication systems because LCX cables radiate weak electromagnetic energy and the environmental effects on their radiation characteristics are small [10, 11]. Once LCX cable is installed, their radiation characteristics are small [10, 11]. One LCX cable is installed along each railway; thus there are two LCX cables along the railway for inbound and outbound train communications, as shown in Figure 9.2. Trains have slot type or patch type antennas at the side of the body that transmits and receives electromagnetic energy to and from the LCX cables.
