| 摘要 |
PROBLEM TO BE SOLVED: To provide a linear antenna system which can be miniaturized and also can reduce a loss in its entire receiving band by placing plural spiral counter poises which are close and substantially parallel to each other with different lengths at the side opposite to an antenna element. SOLUTION: An antenna element 1 is connected to the core conductor of a coaxial cable 4 at a feeding point 1s. The 1st and 2nd counter poises 2 and 3 are provided at the side opposite to the antenna 1 arrounding on the point 1s. One of both ends of each of poises 2 and 3 is connected to the envelope conductor of the cable 4. Both poises 2 and 3 have spiral shapes and are placed on the same plane with difference lengths equal to 1/4 wavelengthsλ1 andλ2 or so, respectively. In such a constitution, a compact linear antenna system is obtained and the poises 2 and 3 are matched with the radio waves of both wavelengthsλ1 andλ2 and also the wavelength set between these two wavelengths. Therefore, the loss can be reduced in the entire bans of both wavelengthsλ1 andλ2 .
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