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Antenna device

  • US 9,196,955 B2
  • Filed: 12/07/2012
  • Issued: 11/24/2015
  • Est. Priority Date: 03/26/2012
  • Status: Active Grant
First Claim
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1. An antenna device comprising:

  • a finite ground plane;

    a feeding point provided on the finite ground plane;

    a plurality of feed antenna elements radially arranged around the feeding point at a height from the finite ground plane;

    a selector switch to connect a first end of a feed antenna element selected from the plurality of feed antenna elements to the feeding point; and

    a plurality of parasitic elements arranged correspondingly to the feed antenna elements,wherein first ends of the parasitic elements are connected to the finite ground plane, and portions including second ends of the parasitic elements are capacitively coupled with the feed antenna elements corresponding to the parasitic elements,wherein a length of each parasitic element is approximately a quarter of a wavelength of a radio frequency to be used,wherein a length from a second end of each feed antenna element to the feeding point is shorter than the length of each parasitic element, andwherein the finite ground plane has a rectangular shape, the first ends of the parasitic elements are connected to corners of the finite ground plane, respectively, and none of the parasitic elements is provided with a switch.

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