To solve the structural compatibility problem between two types of antennas by feeding a base plate of a plane antenna via the 2nd frequency and therefore making one of those two antennas work as another antenna by means of the base plate of the other antenna.
A two-frequency shared antenna contains a cylindrical plane antenna which has a conductive base plate 8 on one of both sides of a dielectric substrate 1 with a microstrip antenna 2 put on the other side of the substrate 1. Thus, the shared antenna can work at a 1st frequency. The edge of the plate 8 of the planar antenna is fed at the 2nd frequency, lower than the 1st frequency and operated. Then the plate 8 can serve as the radiation element of a rod antenna, when the plate 8 is set at the proper length.
MARUYAMA TAMAMI
UEHARA KAZUHIRO
KAGOSHIMA KENICHI
