A multiple-frequency common antenna has a first substrate sheet and a
second substrate sheet respectively structured by an HIP consisting of a
metal plate, small metal plates disposed in two dimensions and linear
metal bars connecting these elements. The antenna restricts propagation
of surface currents of the first and second frequency bands which are not
overlapping with each other. An inverse L-shape antenna and a monopole
antenna which are fed with a center conductor and an external conductor
of the coaxial line respectively operate as the antenna on the first
substrate sheet in the first frequency band and second frequency band.
The second substrate sheet does not propagate the radiated wave of the
monopole antenna, thereby avoiding unwanted re-radiation.