| 摘要 |
In order to provide a broad-band non-grounded type ultrashort-wave antenna which has sufficiently high sensitivity characteristics and broad-band VSWR characteristics even in an expanded frequency band, is able to use a small-diameter antenna element, is light in weight and simple in structure, and can be manufactured inexpensively, an antenna element parallel resonance part, that is formed by the inductance and distributed capacitance of the rod-form antenna element which has an electrical length close to lambda/2 or an integral multiple of lambda/2, and a metal member parallel resonance part, that is formed by the electrostatic capacitance between first and second metal members which are installed parallel to each other and have respective electrical lengths of lambda/4 and the inductance of the first metal member, are electrostatically coupled by the stray capacity that exists between the antenna element and an electrostatic coupling piece projected from the second metal member, thus forming a double-tuned circuit. The antenna thus constructed has the VSWR characteristics of a twin-peak form, thus being suitable for a broader frequency trend and having a desired gain for the entire frequency band used.
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