Spirapole antenna for communication systems utilizing both satellite and terrestrial assets

In this paper an antenna is presented that satisfies the two-fold radiation pattern requirement of communication systems utilizing both geostationary satellites and terrestrial transponders for coverage of mobile terminal away from the equator. A typical requirement for such a system is a low profile antenna that maximizes left-hand circularly polarized radiation in the satellite viewing angle, from 30/spl deg/ to 70/spl deg/ from zenith, and vertically polarized radiation in the terrestrial station viewing angle, from 70/spl deg/ to 90/spl deg/ from zenith. This dual radiation pattern coverage is achieved by integrating a small four arm spiral with a top loaded monopole into a single compact volume, an antenna termed a spirapole.