MULTI-FREQUENCY COMMON ANTENNA AND ANTENNA DEVICE

摘要

PROBLEM TO BE SOLVED: To improve directivity in a plurality of frequencies which are different, respectively.SOLUTION: A multi-frequency common antenna includes: an antenna body which is resonated in a plurality of frequencies being different, respectively; and a single coaxial feeder which includes an inner conductor and an outer conductor covering an outer periphery and supplies power to the antenna body. The coaxial feeder includes at least two pieces of Spertopf disposed at an outer peripheral side of the coaxial feeder. Each Spertopf includes: a dielectric body disposed in an axial direction of the coaxial feeder; and a conductor which covers an outer periphery of the dielectric body and covers an end portion of the dielectric body at a side opposite to a feeding point side. A length of one of the two pieces of Spertopf in the axial direction of the dielectric body is set to a length of 1/4 wavelength in one of the plurality of frequencies, and a length of the other Spertopf in the axial direction of the dielectric body is set to a length of 1/4 wavelength in another frequency between the plurality of frequencies.