Antenna device

• US 9,088,076 B2
• Filed: 02/06/2012
• Issued: 07/21/2015
• Est. Priority Date: 02/10/2011
• Status: Expired due to Fees

• Current Assignee: Panasonic Intellectual Property Management Co., Ltd. (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Intellectual Property Management Co., Ltd. (Panasonic Holdings Corporation)
• Inventors: Fujita, Suguru, Shiozaki, Ryosuke
• Primary Examiner(s): Karacsony, Robert
• Application Number:
  US13/814,901
• Publication Number:
  US 20130141290A1
• Time in Patent Office: 1,261 Days
• Field of Search: 343/724, 343/725, 343/726, 343/727, 343/728, 343/729, 343/741, 343/744, 343/811
• US Class Current: 1/1
• CPC Class Codes: H01Q 1/243 with built-in antennas
• CPC Class Codes: H01Q 19/30 the primary active element being centre-fed and substantially straight, e.g. Yagi antenna
• CPC Class Codes: H01Q 21/29 Combinations of different interacting antenna units for giving a desired directional characteristic H01Q25/00 takes precedence
• CPC Class Codes: H01Q 25/04 Multimode antennas corrugated horns H01Q13/0208
• CPC Class Codes: H01Q 7/00 Loop antennas with a substantially uniform current distribution around the loop and having a directional radiation pattern in a plane perpendicular to the plane of the loop

Abstract

Both ends of a feeder and both ends of a reflector of an antenna device are connected using a pair of diodes. When the diodes are turned on, a loop antenna is formed which loops the feeder, the diode, the reflector, a capacitor, and the diode, and the antenna device operates as the loop antenna. When the diodes are turned off, the antenna device operates as a Yagi-Uda antenna which is formed of the feeder, the reflector, and a wave guide.

Claims

1. An antenna device, comprising:

a feeding conductor;

a first conductor which is disposed at a predetermined distance from the feeding conductor;

a second conductor which is disposed at a predetermined distance from the feeding conductor at an opposite side to the first conductor; and

a plurality of connection elements which connect the second conductor and the feeding conductor, wherein the plurality of connection elements can be switched on and off, respectively, and

wherein each of the plurality of connection elements is turned on when a strength of a received radio wave is larger than a predetermined threshold value, and turned off when the strength of the received radio wave is smaller than the threshold value.

2. The antenna device according to claim 1, further comprising:

a directivity indicator which outputs a signal indicating directivity of radio waves; and

a switching section which switches on and off the plurality of connection elements according to the signal output from the directivity indicator.

3. The antenna device according to claim 1, wherein

the connection elements are PN junction elements.

4. The antenna device according to claim 1, wherein

a length of the feeding conductor is shorter than half of a wavelength of a radio wave for communication frequency by a predetermined amount.

5. The antenna device according to claim 4, further comprising:

a line for wavelength adjustment which is connected between a pair of the connection elements, and having a length, obtained by adding lengths of the feeding conductor and the second conductor, of a value close to 1 wavelength of the radio wave.

6. The antenna device according to claim 5, further comprising:

a plurality of second connection elements which connect the first conductor and the feeding conductor; and

a second line for wavelength adjustment which is connected between a pair of the second connection elements, and having a length, obtained by adding lengths of the feeding conductor and the first conductor, of a value close to 1 wavelength of second radio wave which has different frequency from the radio wave, wherein

the plurality of second connection elements can be switched on and off, respectively.