Antenna for direction finders
First Claim
1. An antenna for direction finders comprising a first conductor forming a loop antenna having opposite ends, an auxiliary conductor having a cut at the top thereof arranged near and in parallel with said first conductor, first capacitor means connected between both ends of said loop antenna for providing a resonant circuit with said loop antenna which is resonant at a first frequency and second capacitor means connected between both ends of said cut of said auxiliary conductor at the top part of said antenna for providing a resonant circuit with said auxiliary conductor which is resonant at a second frequency higher than said first frequency, the values of inductance of said auxiliary conductor and of capacitance of said second capacitor means being selected with respect to the values of inductance of said loop antenna and of capacitance of said first capacitor means so that at a third frequency higher than said second frequency the combination of said auxiliary conductor and second capacitor means provides inductive impedance of such value as to cooperate with said first capacitor means and cause said loop antenna to be resonant at said third frequency permitting a high sensitivity in each narrow band of said first and third frequencies.
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Abstract
This invention relates to an antenna for direction finders presenting a high sensitivity in a narrow band by making a loop antenna and a shielding tube resonate at any two desired frequencies.
27 Citations
3 Claims
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1. An antenna for direction finders comprising a first conductor forming a loop antenna having opposite ends, an auxiliary conductor having a cut at the top thereof arranged near and in parallel with said first conductor, first capacitor means connected between both ends of said loop antenna for providing a resonant circuit with said loop antenna which is resonant at a first frequency and second capacitor means connected between both ends of said cut of said auxiliary conductor at the top part of said antenna for providing a resonant circuit with said auxiliary conductor which is resonant at a second frequency higher than said first frequency, the values of inductance of said auxiliary conductor and of capacitance of said second capacitor means being selected with respect to the values of inductance of said loop antenna and of capacitance of said first capacitor means so that at a third frequency higher than said second frequency the combination of said auxiliary conductor and second capacitor means provides inductive impedance of such value as to cooperate with said first capacitor means and cause said loop antenna to be resonant at said third frequency permitting a high sensitivity in each narrow band of said first and third frequencies.
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2. An antenna according to claim 1 wherein said auxiliary conductor is a shielding tube.
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3. An antenna according to claim 1 wherein said loop antenna is formed to be tubular and said auxiliary conductor is coaxially arranged within this tubular conductor so that the sensitivity at said first frequency is increased.
Specification
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- Resources
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Current AssigneeHyo Yasuda, Kenzo Mori, Norio Ikeda, Yujiro Katsube
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Original AssigneeHyo Yasuda, Kenzo Mori, Norio Ikeda, Yujiro Katsube
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InventorsKatsube, Yujiro, Ikeda, Norio, Mori, Kenzo, Yasuda, Hyo
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Primary Examiner(s)Lawrence, James W.
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Assistant Examiner(s)Nussbaum, Marvin
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Application NumberUS05/338,419Time in Patent Office903 DaysField of Search343/748,741-744,764,841-842,866-869US Class Current343/741CPC Class CodesH01Q 5/378 Combination of fed elements...H01Q 7/04 Screened antennas H01Q7/02,...
