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Nhk Spring Co., Ltd.

Motoaki Uchida

Hiroyuki Arai

Naohisa Goto

Mitsuo Mori

Kiyoshi Seshimo

A conductive layer is formed on one surface of an insulating substrate. Notches are formed in the conductive layer to be axially symmetric at equal angular intervals of 120.degree.. A feeding line of a notch antenna is formed on the other surface of the substrate. The feeding line has a C-shape and wide portions for adjusting the phases of excitation of the notches, and receives power at its one point. A ground plate is arranged to be parallel to the substrate. A feeding rod is connected to the conductive layer. The conductive layer and the ground plate are short-circuited by impedance matching pins. The matching pins are integrally formed with the ground plate. The notches and the feeding line constitute an notch antenna, and the feeding rod, the ground plate, the conductive layer, and the matching pins constitute a capacity loaded monopole antenna. To resonate these antennae at a plurality of resonant points, slits are formed in the conductive layer to be axially symmetric at equal angular intervals of 120.degree., and branch lines are connected to feeding lines. The slits resonate the capacity loaded monopole antenna at a plurality of frequencies. The branch lines resonate the notches at a plurality of frequencies. When the number of branch lines, the number of slits, and the like are adjusted, a diversity antenna covering a plurality of bands can be obtained.

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Yokohama, Japan

Motoaki Uchida