Three-wave shared antenna (radio, am, and fm) for automobile

Claim 1

A three-wave shared antenna for use in an automobile wherein the three-wave shared antenna can transmit/receive a radio mobile telephone wave (an "MT wave") in a radio telephone band, and can receive radio broadcast waves, comprising: a three-step, collinear MT wave element having first and second phasing coils located a predetermined distance apart from each other in an intermediate position along the MT wave element; a trap element having means for interrupting the MT wave, said trap element being at a top portion of the MT wave element; and an auxiliary element for AM and FM radio waves, said auxiliary element including a conductive mast coupled to said MT wave element through said trap element so as to receive AM and FM radio waves in cooperation with said MT wave element; wherein, for a wavelength λ of an electrical wave of a given frequency which is near a frequency of the transmission side in said radio telephone band, said MT wave element comprises: a first element projecting through a wall of a car body and includes a first conductive mast portion whose electrical length is 3/8λ, a second element formed on a top portion of said first element and includes a first phasing coil whose electrical length is 1/4λ, a third element formed on a top portion of said second element and includes a second conductive mast portion whose electrical length is 3/4λ, a fourth element formed on a top portion of said third element and comprising a second phasing coil whose electrical length is 1/4λ, and a fifth element formed on a top portion of said fourth element and comprising a helical coil whose electrical length is 5/8λ to μλ.