Planar antenna

• US 7,522,113 B2
• Filed: 11/28/2005
• Issued: 04/21/2009
• Est. Priority Date: 08/29/2005
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Maniwa, Toru, Andrenko, Andrey
• Primary Examiner(s): Ho; Tan
• Application Number:
  US11/287,234
• Publication Number:
  US 20070046542A1
• Time in Patent Office: 1,240 Days
• Field of Search: 343/725, 343/726, 343/728, 343/833, 343/834, 343/837, 343/700.MS, 343/795, 343/818
• US Class Current: 343/726
• CPC Class Codes: H01Q 1/32 Adaptation for use in or on road or rail vehicles
• CPC Class Codes: H01Q 21/24 Combinations of antenna units polarised in different directions for transmitting or receiving circularly and elliptically polarised waves or waves linearly polarised in any direction circularly polarised patch antennas H01Q9/0428; circularly polarised horns H01Q13/0241; cross-polarised horns H01Q13/0258; polarisation converters H01Q15/242; cross-polarised rear feeds H01Q19/136; crossed polarisation dual antenna H01Q25/001
• 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
• CPC Class Codes: H01Q 9/16 with feed intermediate between the extremities of the antenna, e.g. centre-fed dipole H01Q9/44 takes precedence
• CPC Class Codes: H01Q 9/26 with folded element or elements, the folded parts being spaced apart a small fraction of operating wavelength resonant loop antennas H01Q7/00

Abstract

The present planar antenna include: a linear antenna element to which electric power is to be supplied and a loop-shaped parasitic antenna element placed in the vicinity of said linear antenna element, which are provided on one side of a dielectric substrate. This simple arrangement makes it possible to provide a planar antenna with good circular polarization characteristics.

Claims

1. A planar antenna, comprising:

on one side of a dielectric substrate,

a linear antenna element to which electric power is to be supplied; and

two loop-shaped-parasitic antenna elements, where each of said loop-shaped-parasitic antenna element has a rectangular shape having a long side which is a linear portion extending in a direction which crosses said linear antenna element, placed in the vicinity of said linear antenna element so as to produce cross polarized waves which cross polarized waves produced by said linear antenna element.

2. A planar antenna as set forth in claim 1, wherein said two looped-shaped parasitic antenna elements are placed symmetrically with respect to a center point of said linear antenna element.

3. A planar antenna as set forth in claim 2, wherein said two loop-shaped parasitic antenna elements are provided in the vicinity of the opposite ends of said linear antenna element.

4. A planar antenna as set forth in claim 3, wherein each of said loop-shaped parasitic antenna elements has the rectangular shape in the plane of the dielectric substrate.

5. A planar antenna as set forth in claim 2, wherein each of said loop-shaped parasitic antenna elements has the rectangular shape in the plane of the dielectric substrate.

6. A planar antenna as set forth in claim 1, wherein each of said loop-shaped parasitic antenna elements has the rectangular shape in the plane of the dielectric substrate.

7. A planer antenna as set forth in claim 1, wherein said linear antenna element is a dipole antenna.