Wideband tunable antenna

摘要

The present invention provides an antenna device capable of automatically obtaining excellent receiving sensitivity over a wide band. The antenna device comprises a rod-shaped base made of a dielectric material or a magnetic material; a stripe-shape radiating conductor divided into a plurality of radiating conductors wound around the base; and variable capacitive elements provided to correspond to the same number of the radiating conductors. The radiating conductors and the variable capacitive elements are alternatively arranged on the base and are connected in series to each other, the radiating conductor having its one end connected to the variable capacitive element serves as an open side and the variable capacitive element having its one end connected to the radiating conductor serves as a signal feeding side, and capacitance values of the variable capacitive elements increase or decrease in the same direction to be tuned to a predetermined frequency. <IMAGE>