Unbalanced antenna

• US 7,180,466 B2
• Filed: 10/15/2003
• Issued: 02/20/2007
• Est. Priority Date: 10/23/2002
• Status: Expired due to Fees

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Kuroda, Shinichi
• Primary Examiner(s): Ho; Tan
• Application Number:
  US10/498,518
• Publication Number:
  US 20060214869A1
• Time in Patent Office: 1,224 Days
• Field of Search: 343/700.MS, 343/702, 343/846, 343/848, 343/773
• US Class Current: 343/846
• 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 that are provided with a predetermined gap therebetween, wherein the ground conductor comprises:

a predetermined part functioning as a pole for forming a near electromagnetic-field distribution together with the radiation conductor opposed to the ground conductor and a predetermined part for contributing to impedance matching.

2. An unbalanced antenna according to claim 1,

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

wherein a predetermined part of the ground conductor includes a conductor having low conductivity, the predetermined part being 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

wherein at least one part of an external conductor of a substantially coaxial feed line connected to a feed section 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.

6. 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.

7. An unbalanced antenna comprising a radiation conductor and a ground conductor that are provided with a predetermined gap therebetween,

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.

8. An unbalanced antenna according to claim 7,

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.

9. An unbalanced antenna according to claim 7,

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

10. An unbalanced antenna according to claim 9, wherein the conductivity of the electric resistor, the electric resistor being near the feed section, is set to a low level, and wherein the conductivity of the electric resistor, the electric resistor being near the end, is set to a high level.

11. An unbalanced antenna comprising:

a single-layered dielectric substrate having two electrode surfaces, that is, upper-layer and lower-layer electrode surfaces;

a plate-like radiation electrode and a transmission-line electrode connected to the radiation electrode that are formed on one of surfaces of the single-layered dielectric substrate;

a ground electrode formed near a predetermined part of the other surface of the single-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 sub-ground electrode; and

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

12. An unbalanced antenna according to claim 11,

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

13. An unbalanced antenna according to claim 11,

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

14. An unbalanced antenna according to claim 11,

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

15. An unbalanced antenna comprising:

a single-layered dielectric substrate having two electrode surfaces, that is, upper-layer and lower-layer electrode surfaces;

a plate-like radiation electrode and a transmission-line electrode connected to the radiation electrode that are formed on one of surfaces of the single-layered dielectric substrate;

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

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

16. An unbalanced antenna according to claim 15,

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

17. An unbalanced antenna according to claim 15,

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

18. An unbalanced antenna according to claim 15,

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

19. An unbalanced antenna comprising:

a multi-layered dielectric substrate having three electrode surfaces, that is, upper-layer, intermediate-layer, and lower-layer electrode surfaces;

a plate-like radiation electrode and a transmission-line electrode connected to the radiation electrode that are 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 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 for electrically connecting 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.

20. An unbalanced antenna according to claim 19, 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.

21. An unbalanced antenna according to claim 19, further comprising:

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

22. An unbalanced antenna according to claim 19,

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

23. An unbalanced antenna according to claim 19,

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

24. An unbalanced antenna according to claim 19,

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

25. An unbalanced antenna comprising:

an insulator having opposing end faces;

a radiation electrode formed on a surface of a substantially cone-shaped indentation formed on one of end faces of the insulator, or formed in the indentation, so as to fill the entire indentation;

a radiation-electrode extension portion formed by extending the radiation electrode from an approximate apex of the indentation so that the radiation-electrode extension portion reaches the other end face opposed to the end face of the insulator;

a ground electrode formed on the other end face of the insulator, so as to enclose the radiation-electrode extension portion;

at least one circumferential slit portion formed by peeling off a predetermined periphery part of the ground electrode;

an electric resistor embedded in the circumferential slit portion; and

an electric-signal feed section provided between the radiation-electrode extension portion and the ground electrode.

26. An unbalanced antenna according to claim 25, wherein the size of the ground electrode is substantially the same as that of the base of the indentation.

27. An unbalanced antenna according to claim 25, wherein the ground electrode has a step, where the circumferential slit portion constitutes an edge of the step.