Antenna

Claim 1

An antenna capable of receiving electromagnetic signals in three different frequency bands, comprising: an antenna element (1) having a trap coil (12); and wherein said antenna element is formed such that the electric length from the bottom end of said antenna to the trap coil is resonant with signals in the first frequency band, an electric length from the bottom end of said antenna to said antenna top is resonant with signals in the second frequency band, and an electric length of the whole antenna element receives signals in the third frequency band, characterised in that said antenna further comprises an antenna case comprising branching filter means (3,4), amplifiers (5,6), and a combiner (7), the antenna element being fixed in use to said antenna case, wherein said branching filter means (3,4) separates and outputs said signals in the first frequency band, and inputs said signals in the second and third frequency bands into respective amplifiers (5,6), said amplifiers outputting amplified signals at said second and third frequencies, said amplified signals being combined by said combiner (7) and output from said antenna case; wherein said antenna case comprises a cover (19) and a base (18), said cover comprising a metal fitting portion (23) having a depression for connecting the antenna element fixed watertightly at the top portion of said cover so that said depression faces the outside, said metal fitting portion having an internal engaging portion (28) at the bottom thereof; and a metal connecting piece (26) electrically connected with a substrate (20) fixed to said base, wherein an external engaging portion (27) is formed at one end of said metal connecting piece (26) by making cuts in radial directions so as to have tongues (30) bend downward, and said cover is pressed to insert said internal engaging portion (28) into said external engaging portion (27) so that said metal fitting portion (23) is electrically connected to said substrate.