UNBALANCED ANTENNA

• US 20070176828A1
• Filed: 12/26/2006
• Published: 08/02/2007
• Est. Priority Date: 10/23/2002
• Status: Active Grant

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: KURODA, Shinichi
• Granted Patent: US 7,515,114 B2
• Time in Patent Office: Days
• US Class Current: 343/700.MS
• 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 1/48 Earthing means; Earth screens; Counterpoises
• CPC Class Codes: H01Q 17/001 for modifying the directional characteristic of an aerial
• CPC Class Codes: H01Q 9/0407 Substantially flat resonant element parallel to ground plane, e.g. patch antenna dipole H01Q9/285; monopole H01Q9/40
• 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 9/38 with counterpoise with counterpoise comprising elongated elements coplanar with the active element H01Q9/44
• CPC Class Codes: H01Q 9/40 Element having extended radiating surface

Abstract

An unbalanced antenna having a radiation conductor and a ground conductor provided with a predetermined gap therebetween is provided. At least a predetermined part of the ground conductor, the predetermined part being opposed to the radiation conductor, is left so that it keeps functioning as a pole for forming a near electromagnetic-field distribution together with the radiation conductor opposed to the ground conductor. Further, a part of the reduced ground conductor, the part being near an end at a predetermined distance from the feed section, includes a conductor having low conductivity for obtaining impedance matching. Where the ground conductor is significantly reduced, mode mismatch inevitably occurs. Therefore, at least one part of an external conductor of a coaxial feed line connected to the feed section is covered by a current absorber, so as to forcefully reduce a leakage current. Subsequently, the ground conductor can be reduced and the antenna characteristic can be maintained.

Claims

1. An unbalanced antenna comprising:

a radiation conductor; and

a ground conductor disposed with a predetermined gap relative to the radiation conductor, wherein the ground conductor further includes

a first predetermined part configured to function as a pole for forming a near electromagnetic-field distribution together with the radiation conductor opposed to the ground conductor, and

a second predetermined part for contributing to impedance matching.

2. An unbalanced antenna according to claim 1, wherein:

the ground conductor is reduced in size relative to a size of the radiation conductor except at least a predetermined part substantially opposed to the radiation conductor, and

the ground conductor includes a portion having low conductivity near an end at a predetermined distance from a feed section.

3. An unbalanced antenna according to claim 1,

wherein the ground conductor further has a predetermined part contributing to mode matching by reducing a leakage current generated from a feed section.

4. An unbalanced antenna according to claim 1, wherein:

feeding is achieved via a substantially coaxial transmission line, and

at least one part of an external conductor of the substantially coaxial feed line is connected to a feed section and is covered by a current absorber.

5. An unbalanced antenna according to claim 1,

wherein, conductivity of the ground conductor is reduced continuously or in stages along a direction from a part near the feed section to an end.

10. An unbalanced antenna according to claim 1, wherein a Sperrtopf tube or a current blocking system analogous thereto is provided on an external conductor of a substantially coaxial transmission line connected to the feed section of the unbalanced antenna.

6. An unbalanced antenna comprising:

a radiation conductor; and

a ground conductor disposed with a predetermined gap relative to the radiation conductor, wherein

the ground conductor is reduced in size except at least a predetermined part substantially opposed to the radiation conductor and divided into a plurality of parts according to a distance from a feed section, and wherein electric resistors are connected between the divided ground conductors.

7. An unbalanced antenna according to claim 6,

wherein a predetermined part of an external conductor of a substantially coaxial transmission line connected to the feed section of the unbalanced antenna is covered by a current absorber.

8. An unbalanced antenna according to claim 6,

wherein at least an electric resistor having a suitable resistivity is respectively provided between the divided ground conductors.

9. An unbalanced antenna according to claim 8, wherein:

the conductivity of the electric resistor near the feed section is set to a low level, and

the conductivity of the electric resistor near the end is set to a high level.

11. An unbalanced antenna according to claim 6, wherein a Sperrtopf tube or a current blocking system analogous thereto is provided on an external conductor of a substantially coaxial transmission line connected to the feed section of the unbalanced antenna.

12. An unbalanced antenna comprising:

a dielectric substrate having an upper-layer electrode surface and a lower-layer electrode surface;

a substantially planar radiation electrode;

a transmission-line electrode connected to the radiation electrode, said radiation electrode and said transmission-line electrode being formed on the upper-layer surface or the lower-layer surface of the dielectric substrate;

a ground electrode formed near a predetermined part of a surface of the dielectric substrate that does not have the radiation electrode disposed thereon, and being opposed to the transmission-line electrode;

at least one sub-ground electrode disposed adjacent to the ground electrode;

an electric resistor connected between the ground electrode and the at least one sub-ground electrode; and

an electric-signal feed path provided between the transmission-line electrode and the ground electrode.

17. An unbalanced antenna according to claim 12,

wherein an entire breadth of the ground electrode including the sub-ground electrode is set so as to be substantially the same as that of the radiation electrode.

20. An unbalanced antenna according to claim 12,

wherein the electric resistor is formed by using a chip-type resistor.

23. An unbalanced antenna according to claim 12,

wherein a plurality of the sub-ground electrodes is provided end to end, so as to be adjacent to one another.

13. An unbalanced antenna comprising:

a dielectric substrate having an upper-layer electrode surface and a lower-layer electrode surface;

a substantially planar radiation electrode;

a transmission-line electrode connected to the radiation electrode, said radiation electrode and said transmission-line electrode being formed on the upper-layer surface or the lower-layer surface of the dielectric substrate;

a ground electrode that is flush with the radiation electrode and the transmission-line electrode and is divided so as to sandwich the transmission-line electrode;

at least one sub-ground electrode disposed adjacent to the ground electrode;

an electric resistor connected between the ground electrode and the at least one sub-ground electrode; and

an electric-signal feed path provided between the transmission-line electrode and the ground electrode.

18. An unbalanced antenna according to claim 13,

wherein an entire breadth of the ground electrode including the sub-ground electrode is set so as to be substantially the same as that of the radiation electrode.

21. An unbalanced antenna according to claim 13,

wherein the electric resistor is formed by using a chip-type resistor.

24. An unbalanced antenna according to claim 13,

wherein a plurality of the sub-ground electrodes is provided end to end, so as to be adjacent to one another.

14. An unbalanced antenna comprising:

a multi-layered dielectric substrate having three electrode surfaces, including an upper-layer, an intermediate-layer, and a lower-layer electrode surface;

a substantially planar radiation electrode and a transmission-line electrode connected to the radiation electrode that is formed on the intermediate-layer surface of the multi-layered dielectric substrate;

a ground electrode formed near a predetermined part of the lower-layer surface of the multi-layered dielectric substrate, the predetermined part being opposed to the transmission-line electrode;

at least one sub-ground electrode provided, so as to be adjacent to the ground electrode;

an electric resistor connected between the ground electrode and the at least one sub-ground electrode;

an opposed ground electrode formed near a predetermined part of the upper-layer surface of the multi-layered dielectric substrate, the predetermined part being opposed to the transmission-line electrode;

two or more inter-ground-electrode connection sections configured to electrically connect the ground electrode to the opposed ground electrode; and

an electric-signal feed path formed between the transmission-line electrode and the ground electrode, and/or the transmission-line electrode and the opposed ground electrode.

15. An unbalanced antenna according to claim 14, wherein the inter-ground-electrode connection sections are provided on both sides of the transmission-line electrode provided on the intermediate-layer surface of the multi-layered dielectric substrate, so as to sandwich the multi-layered dielectric substrate.

16. An unbalanced antenna according to claim 14, further comprising:

a current absorber covering a predetermined part of a periphery of the ground electrode and the opposed ground electrode.

19. An unbalanced antenna according to claim 14,

wherein an entire breadth of the ground electrode including the sub-ground electrode is set so as to be substantially the same as that of the radiation electrode.

22. An unbalanced antenna according to claim 14,

wherein the electric resistor is formed by using a chip-type resistor.

25. An unbalanced antenna according to claim 14,

wherein a plurality of the sub-ground electrodes is provided end to end, so as to be adjacent to one another.