Base station antennas inside tunnels and subway stations, and outdoor compact base station antennas for PDC system in Japan

Presents base station antennas for the microcellular system used for the Japanese PDC system. The main base station antennas are macrocellular and the coverage area is 1.5 km to 3 km in radius. However, we have many places that are not covered by macrocellular base stations, such as highway tunnels, subway stations, and underground shopping malls. The services for these places are given by microcellular or booster systems. The coverage area is 200 m to 1 km. The base station antennas for this purpose should have special characteristics, for example, bi-directional radiation pattern, multi-frequency use, and polarization diversity. This paper presents examples of these base station antennas that are used in the present system. For example, a bi-directional notch antenna for the tunnel booster system, and a dielectric filled disk loaded monopole antenna for subway stations are presented. Dielectric-filled antennas are also used for base stations to provide services inside large buildings. In addition, this paper presents compact base station antennas. These base stations are used for the places in which the traffic is temporary increased such as a big exhibition, and in case of a disaster. The base station antenna should be compact to carry it, and should have diversity branches. The polarization diversity antennas used for the Nagano Olympic Games are presented. The compact base stations are also used for spot coverage systems. The PDC service is provided partly outside the coverage area of the present macrocellular system, such as resort areas. The several examples for these antennas are presented.