The present invention provides a broad-band antenna for mobile communication
in which a desired antenna characteristic is obtained in plural frequency bands
of a portable phone or the like. A metal plate 16 having a suitable shape
is disposed on an upper surface of a carrier 14 provided on a circuit board
10, and a first and a second antenna elements functioning as inverted-F
antennas respectively resonant at a first frequency band and a second frequency
band higher than the former are formed by electrically connecting the metal plate
16 to a grounding plate 12 and the circuit board 10 by an
earthing terminal 18 and a feed terminal 20, respectively. A third
antenna element 24 having a base end electrically connected to the feed
terminal 20 and resonant at a third frequency band higher than the second
frequency band is provided on a side surface of the carrier 14, ends of
the second antenna element and the third antenna element 24 are disposed
to be spaced from each other by a distance of 0.1 wavelength or more of the third
frequency band, and the end of the third antenna element 24 is disposed
to be spaced from the grounding plate 12 by a distance of 0.01 wavelength
or more of the third frequency band. Besides, the third antenna element may be
made resonant at a fourth frequency band higher than the third frequency band,
and a matching circuit to perform matching for the third frequency band may be provided.
