Applications of the figure-8 satellite system

The figure-8 satellite (quasi-zenithal satellite) system is a satellite con stellation consisting of three or more satellites placed in inclined gee-sy nchronous circular orbits with an identical inclination of around 45 degree s. At any time, at least one of the three satellites is moving near the zen ith view from Japan. The sub-satellite point traces a so-called 'figure of eight' locus on the ground, elongating in the north-south direction with an arbitrary point on the equator in the center. The figure-8 satellite syste m has several potential applications including mobile satellite communicati ons at a high-elevation angle, dual use of the same frequency between geost ationary satellites and figure-8 satellites in fixed-satellite services, sa tellite-based positioning, and observation of the polar region. This paper describes applications of the figure-8 satellite system Zn particular, the applicability of the satellite system to mobile satellite communications is shown by the experimental results of tests using the COMETS satellite.