Patent ID: 6985121

Claim:
A multiband antenna comprising a lower conductive tube and first, second, third and fourth upper conductive tubes, all of the conductive tubes spaced from each other and disposed on the same longitudinal axis, a first transmission line extending within the lower conductive tube to a first feed point located between and connected to the lower conductive tube and the first upper conductive tube, a second transmission line extending within the lower conductive tube and the first and second upper conductive tubes to a second feed point, a third transmission line extending within the second upper conductive tube from the second feed point to a third feed point located between and connected to the first and second upper conductive tubes, a fourth transmission line extending within the third upper conductive tube from the second feed point to a fourth feed point located between and connected to the third and fourth upper conductive tubes, and isolation circuits connected between the upper conductive tubes, wherein the lower conductive tube and the upper conductive tubes form a center-fed low frequency dipole radiator, centered on the first feed point, that resonates in a lower frequency band for signals transmitted along the first transmission line, and wherein the first and second upper conductive tubes form a 1 st high frequency dipole radiator centered on the third feed point, and the third and fourth upper conductive tubes form a 2 nd high frequency dipole radiator centered on the fourth feed point, the 1 st and 2 nd high frequency dipole radiators resonating in a higher frequency band for signals transmitted along the second transmission line by way of the second feed point.