| 摘要 |
An antenna includes a dipole (20) with upper and lower elongated conductors (22, 24) and a feedline (40) for carrying radio frequency currents to the dipole by connecting the feedline to the lower end (30) of the upper conductor and to the upper end (32) of the lower conductor, which produces maximum gain. A spacer (50) spaces the center of the feedline by a distance (A) of about 3 centimeters from the center of the lower conductor, to produce minimum losses while providing a compact antenna. A toroidal ferrite core (110) lies at the bottom of the lower conductor and the feedline is in the form of a wire pair that is wrapped a plurality of times about the ferrite core to prevent signals radiated by the lower conductor and picked up by the feedline, from passing to the radio. A tuning member (150) of electrically conductive material can be slid along the spacer to tune the antenna without changing its height (B).
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