ANTENNA

• US 20080122724A1
• Filed: 10/30/2007
• Published: 05/29/2008
• Est. Priority Date: 04/14/2006
• Status: Active Grant

• Current Assignee: Murata Manufacturing Co Limited
• Original Assignee: Murata Manufacturing Co Limited
• Inventors: KATO, Noboru
• Granted Patent: US 7,786,949 B2
• Time in Patent Office: Days
• US Class Current: 343/867
• CPC Class Codes: H01Q 1/243 with built-in antennas
• CPC Class Codes: H01Q 1/38 formed by a conductive layer on an insulating support patch antennas H01Q9/0407; microstrip dipole antennas H01Q9/065; microstrip slot antennas H01Q13/106; transmission line microstrip antennas H01Q13/206; manufacturing reflecting surfaces using insulating material for supporting the reflecting surface H01Q15/142
• CPC Class Codes: H01Q 1/50 Structural association of antennas with earthing switches, lead-in devices or lightning protectors
• CPC Class Codes: H01Q 5/321 within a radiating element or between connected radiating elements
• CPC Class Codes: H01Q 5/371 Branching current paths
• CPC Class Codes: H01Q 5/40 Imbricated or interleaved structures; Combined or electromagnetically coupled arrangements, e.g. comprising two or more non-connected fed radiating elements
• 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 9/27 Spiral antennas

Abstract

An antenna includes inductance elements that are magnetically coupled together, an LC series resonant circuit that includes one of the inductance elements and capacitance elements, and an LC series resonant circuit that includes another of the inductance elements and capacitance elements. The plurality of LC series resonant circuits are used to radiate radio waves and are used as inductances of a matching circuit that matches an impedance when a power supply side is viewed from power supply terminals and a radiation impedance of free space.

Claims

1. An antenna circuit comprising:

a power supply terminal; and

a radiating element being electrically connected to the power supply terminal;

wherein

the radiating element includes at least two inductance elements arranged to radiate radio waves;

the first and second inductance elements have different inductance values from one another; and

the first and second inductance elements are magnetically coupled to each other.

2. The antenna circuit according to claim 1, wherein the first and second inductance elements are connected in parallel with regard to the power supply terminal.

3. The antenna circuit according to claim 1, further comprising a first capacitance element;

wherein

the first capacitance element and the first inductance element define a first resonant circuit.

4. The antenna circuit according to claim 3, further comprising a second capacitance element;

wherein

the second capacitance element and the second inductance element define a second resonant circuit; and

the first and second resonant circuit are magnetically coupled to each other.

5. The antenna circuit according to claim 3, wherein the first capacitance element is disposed between the power supply terminal and the first inductance element.

6. The antenna circuit according to claim 1, wherein a plurality of radiating elements is arranged in parallel.

7. The antenna circuit according to claim 1, wherein a plurality of radiating elements is arranged in series.

8. The antenna circuit according to claim 1, wherein a coupling coefficient between the first and second inductance elements is at least about 0.1.

9. The antenna circuit according to claim 1, further comprising a substrate;

wherein

the substrate includes the power supply terminal and the radiating element including the first and second inductance elements.

10. The antenna circuit according to claim 9, wherein the first and second inductance elements are provided on at least one common surface of the substrate.