| 摘要 |
The present invention relates to a wideband VHF antenna of omnidirectional directivity, comprising a substantially vertical elongated structure consisting of an upper part consisting of a plurality of wires of different length, electrically insulated from each other, of a length of about one-fourth of the longest wave-length to about one-fourth of the shortest wave-length of the waveband, arranged with their contiguous parts parallel with each other and close to each other, and a lower part in the form of a coaxial structure, the lower ends of the said wires being connected with the inner wire of the said coaxial structure, said inner wire constituting an impedance multi-step transformer of at least two stages, said inner wire constituting the winding of at least one ferrite torroid forming an effective ground isolation, the outer conducting sheath of the coaxial structure constituting the lower part of the dipole, the impedance of the antenna being matched to that of the receiver and/or transmitter with which it is to be used. A preferred embodiment relates to an antenna for use in the 30 to 88 MHz waveband from 3 to 12 wires in the upper part, of a length from 85 to 182 cm. |
