| US 7,545,340 B2 | ||
| Compact antenna having coaxial helical elements with ends connected across an RF signal source | ||
| Akira Takaoka, Okazaki (Japan); and Noriaki Okada, Chiryu (Japan) | ||
| Assigned to Denso Corporation, Kariya, Aichi-Pref. (Japan); and Nippon Soken, Inc., Nishio, Aichi-Pref. (Japan) | ||
| Filed on Jun. 28, 2006, as Appl. No. 11/476,197. | ||
| Claims priority of application No. 2005-188513 (JP), filed on Jun. 28, 2005; and application No. 2006-106787 (JP), filed on Apr. 07, 2006. | ||
| Prior Publication US 2006/0290590 A1, Dec. 28, 2006 | ||
| Int. Cl. H01Q 1/36 (2006.01); H01Q 1/24 (2006.01) | ||
| U.S. Cl. 343—895 [343/702] | 9 Claims |
| 1. An antenna for transmitting and receiving a radio wave having a predetermined wavelength, the antenna comprising:
an outer element including a first plurality of helical turns of a first diameter disposed along a central axis; and
an inner element including a second plurality of helical turns of a second diameter also disposed co-axially along a common
portion of said central axis, wherein:
said first diameter is larger than said second diameter sufficient to provide a predetermined spatial separation between said
outer and inner elements;
the outer element and inner element being connected across an RF signal source, thus providing a balanced RF alternating current
circuit having one side connected to said outer element and the other side connected to said inner element, such that the
outer and inner elements alternately serve as signal and ground lines because of an RF current flowing through the outer and
inner elements.
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