Abstract: A dual-band antenna for mobile communication unit is provided with a support made of an insulating material, double stranded helical conductors, and a coaxial feeder connected to an end of each of the helical conductors. The double stranded helical conductors are wound in an identical direction on the support without intersecting each other to have different resonance frequencies, respectively, a winding region of the second helical conductor being a part of that of the first helical conductor. When a voltage is applied to the first and the second helical conductors through the coaxial feeder, the antenna operates in the optimum performance at two frequency bands. As a result, the unit can use a desired different mobile telecommunication service without changing it. Further, the inventive antenna is designed to be small in size to thereby allow it to be adapted on the mobile telecommunication unit.

Abstract: A dual-band antenna for mobile communication unit is provided with a support made of an insulating material, double stranded helical conductors, and a coaxial feeder connected to an end of each of the helical conductors. The double stranded helical conductors are wound in an identical direction on the support without intersecting each other to have different resonance frequencies, respectively, a winding region of the second helical conductor being a part of that of the first helical conductor. When a voltage is applied to the first and the second helical conductors through the coaxial feeder, the antenna operates in the optimum performance at two frequency bands. As a result, the unit can use a desired different mobile telecommunication service without changing it. Further, the inventive antenna is designed to be small in size to thereby allow it to be adapted on the mobile telecommunication unit.

Abstract: A dual-band antenna for mobile communication unit is provided with a support made of insulating materials, a first and a second helical conductors, and a coaxial feeder connected to an end of each of the helical conductors. The first and the second helical conductors are wound on the support to be separated from each other and have a different resonance frequency, respectively. When a voltage is applied to the first and the second helical conductors through the coaxial feeder, the antenna operates in the optimum performance at two frequency bands. As a result, the unit can use a desired different mobile telecommunication service without changing it. Further, the inventive antenna is designed to be small in size to thereby allow it to be adapted on the mobile telecommunication unit.

Abstract: A multilayered helical antenna for mobile communication units includes a first dielectric sheet, a plurality of second dielectric sheets, a plurality of second and third dielectric sheets. All of the second dielectric sheets, except one, have a starting hole and an ending hole, with the exception having the starting hole only. Each of the second dielectric sheet is provided with a partially opened circular metallic pattern. Each of the third dielectric sheets has a via hole. Each of the dielectric sheets has a through-hole at a center thereof in order to allow a whip antenna to be slid upward and downward along a center axis of a helical antenna which is formed by stacking the dielectric sheets in a predetermined order.