ANTENNA APPARATUS AND WIRELESS COMMUNICATION APPARATUS

• US 20110134011A1
• Filed: 11/05/2010
• Published: 06/09/2011
• Est. Priority Date: 12/04/2009
• Status: Abandoned Application

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Yamagajo, Takashi
• Application Number:
  US12/940,386
• Publication Number:
  US 20110134011A1
• Time in Patent Office: Days
• US Class Current: 343/860
• 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 23/00 Antennas with active circuits or circuit elements integrated within them or attached to them
• CPC Class Codes: H01Q 9/30 with feed to end of elongated active element, e.g. unipole H01Q9/44 takes precedence
• CPC Class Codes: H01Q 9/42 with folded element, the folded parts being spaced apart a small fraction of the operating wavelength

Abstract

An antenna apparatus includes an antenna linear element including a linear conductor provided with a first end and a second end, a ground conductor connected to the linear conductor at the second end, a transmission line connected to the linear conductor at the first end, and a matching circuit including a first impedance adjustment element connected to the transmission line at an end on an opposite side to the end of transmission line connected to the linear conductor and a second impedance adjustment element which is connected to the first impedance adjustment element on an opposite side to the end of the first impedance adjustment element connected to the transmission line and an end of which on an opposite side to the end connected to the first impedance adjustment element is grounded, a connection part between the first impedance adjustment element and second impedance adjustment element receiving a power feed.

Claims

1. An antenna apparatus provided with a matching circuit, the antenna apparatus comprising:

an antenna linear element including a linear conductor provided with a first end and a second end;

a ground conductor connected to the linear conductor at the second end;

a transmission line connected to the linear conductor at the first end; and

a matching circuit including a first impedance adjustment element connected to the transmission line at an end on an opposite side to the end of the transmission line connected to the linear conductor and a second impedance adjustment element which is connected to the first impedance adjustment element at an end on an opposite side to the end of the first impedance adjustment element connected to the transmission line and an end of which on an opposite side to the end connected to the first impedance adjustment element is grounded, a connection part between the first impedance adjustment element and the second impedance adjustment element receiving a power feed.

2. The antenna apparatus according to claim 1, wherein:

a range of a use frequency used for transmission or reception in the antenna apparatus is determined;

an electric length of the antenna linear element is equal to a length of ¼

of a wavelength corresponding to a predetermined frequency within the range of the use frequency;

when the antenna linear element and the transmission line are viewed as a single load circuit, within the range of the use frequency, a real part of an impedance of the single load circuit is equal to or smaller than a characteristic impedance of the transmission line, and also an imaginary part of the impedance of the single load circuit is smaller than 0; and

within the range of the use frequency, a real part of an admittance of the single load circuit is equal to or smaller than a reciprocal of the characteristic impedance of the transmission line.

3. The antenna apparatus according to claim 1, wherein:

a range of a use frequency used for transmission or reception in the antenna apparatus is determined;

the transmission line is provided in such a manner that an impedance of the antenna linear element moves to a predetermined area on a Smith chart within the range of the use frequency;

the first impedance adjustment element adjusts the moved impedance to have a predetermined impedance value within a predetermined range; and

the second impedance adjustment element adjusts the adjusted impedance to a center on the Smith chart.

4. The antenna apparatus according to claim 1, wherein an extending direction of the linear conductor is inverted in mid-course, and the linear conductor has an outward linear element extending from the first end to an inverted position of the extending direction and an inward linear element extending from the inverted position to the second end while being in parallel to the outward linear element.

5. The antenna apparatus according to claim 4, wherein a line width of the inward linear element of the antenna linear element is wider than a line width of the outward linear element.

6. The antenna apparatus according to claim 1, wherein a line length of the transmission line is shorter than ¼

of a wavelength corresponding to a use frequency used for transmission or reception in the antenna apparatus.

7. The antenna apparatus according to claim 1, wherein the first impedance adjustment element and the second impedance adjustment element are inductance elements.

8. The antenna apparatus according to claim 7, wherein the matching circuit includes a variable capacitor connected in series to the first impedance adjustment element.

9. The antenna apparatus according to claim 8, wherein the variable capacitor is one of a varactor diode and an MEMS variable capacitor fabricated through MEMS (Micro Electro Mechanical Systems).

10. The antenna apparatus according to claim 1, wherein:

the ground conductor, the transmission line, and the antenna linear element are provided on a dielectric substrate;

the ground conductor is provided on a surface on an opposite side to a surface of the dielectric substrate where the transmission line is provided;

the transmission line forms a microstrip line together with the ground conductor; and

the second end of the antenna linear element is connected to the ground conductor via a via conductor penetrating through the dielectric substrate.

11. The antenna apparatus according to claim 1, wherein:

the ground conductor, the transmission line, and the antenna linear element are provided on a dielectric substrate;

the ground conductor is provided on a same surface as a surface of the dielectric substrate where the transmission line is provided; and

the transmission line forms a coplanar line together with the ground conductor.

12. The antenna apparatus according to claim 1, wherein:

the ground conductor, the transmission line, and the antenna linear element are provided on a dielectric substrate;

the ground conductor is provided on both surfaces of the dielectric substrate; and

the transmission line is a strip line provided in an inner part of the dielectric substrate.

13. A wireless communication apparatus comprising:

the antenna apparatus as claimed in claim 1;

a transmission/reception circuit connected to the antenna apparatus; and

a signal processing apparatus connected to the transmission/reception circuit and configured to process a signal to be transmitted or a received signal.