Multi-band monopole planar antennas configured to facilitate improved radio frequency (RF) isolation in multiple-input multiple-output (MIMO) antenna arrangement

• US 10,096,909 B2
• Filed: 03/30/2017
• Issued: 10/09/2018
• Est. Priority Date: 11/03/2014
• Status: Active Grant

• Current Assignee: Corning Optical Communications LLC (Corning Incorporated)
• Original Assignee: Corning Optical Communications Wireless Ltd. (Corning Incorporated)
• Inventors: Schwartzman, Ronen, Tzur, Yuval
• Primary Examiner(s): WILLIAMS, HOWARD L
• Application Number:
  US15/473,977
• Publication Number:
  US 20170207548A1
• Time in Patent Office: 558 Days
• Field of Search: None
• 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 1/523 between antennas of an array
• 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 5/30 Arrangements for providing operation on different wavebands
• CPC Class Codes: H01Q 5/364 Creating multiple current paths
• CPC Class Codes: H01Q 9/36 with top loading
• CPC Class Codes: H01Q 9/40 Element having extended radiating surface

Abstract

Embodiments disclosed include multi-band monopole planar antennas configured to facilitate radio frequency (RF) isolation in multiple-input multiple-output (MIMO) antenna arrangement. In one aspect, a multi-band monopole planar antenna is provided and configured to generate a slant 45° radiation polarization in the lower frequency band. As a result, sufficient RF isolation may be achieved in the lower frequency band when a plurality of dual-band monopole planar antennas is placed in the MIMO arrangement. In another aspect, the multi-band monopole planar antenna is configured not to support certain unused RF bands, thus facilitating height reduction in the multi-band monopole planar antenna. By configuring the dual-band monopole planar antenna to generate the slant-45 radiation polarization in the lower frequency band, a plurality of the multi-band monopole planar antennas may be placed in close proximity to each other to support MIMO operation without compromising RF performance.

Claims

1. A dual-band monopole planar antenna, comprising:

a semi-elliptical shaped conductive disc having a symmetrical center axis;

a slot disposed in the semi-elliptical shaped conductive disc along a longitudinal axis substantially perpendicular to the symmetrical center axis to separate the semi-elliptical shaped conductive disc into a first conductive disc section and a second conductive disc section;

a conductive delay line having a first end feed point and a second end feed point disposed in the slot, wherein the first end feed point is conductively coupled to the first conductive disc section and the second end feed point is conductively coupled to the second conductive disc section; and

a disc feed point disposed in the first conductive disc section, wherein the disc feed point is configured to receive an electrical current from an electrical current source;

wherein the conductive delay line is configured to receive the electrical current from the first conductive disc section at the first end feed point and provide the electrical current to the second conductive disc section at the second end feed point;

wherein the first conductive disc section is configured to radiate electromagnetic energy on a first radio frequency (RF) band with a first radiation polarization in response to receiving the electrical current from the disc feed point; and

wherein the second conductive disc section is configured to radiate electromagnetic energy on a second RF band having lower frequency than the first RF band with a second radiation polarization different from the first radiation polarization in response to receiving the electrical current from the second end feed point of the conductive delay line.

2. The dual-band monopole planar antenna of claim 1, wherein a respective surface area of the first conductive disc section determines an impedance bandwidth for the first RF band.

3. The dual-band monopole planar antenna of claim 2, wherein a respective surface area of the second conductive disc section determines a respective impedance bandwidth for the second RF band.

4. The dual-band monopole planar antenna of claim 3, wherein a respective length of the conductive delay line is measured between the first end feed point and the second end feed point, wherein the respective length of the conductive delay line determines a lower RF boundary of the second RF band.

5. The dual-band monopole planar antenna of claim 4, wherein the conductive delay line is disposed horizontally along the longitudinal axis.

6. The dual-band monopole planar antenna of claim 4, wherein the first radiation polarization is a vertical radiation polarization.

7. The dual-band monopole planar antenna of claim 4, wherein the second radiation polarization is an approximate slant 45°

(slant-45) radiation polarization.

8. The dual-band monopole planar antenna of claim 4, wherein:

the first RF band is between approximately 1700 megahertz (MHz) and 2700 MHz; and

the second RF band is between approximately 698 MHz and 894 MHz.

9. A dual-band antenna element, comprising:

a first dual-band monopole planar antenna mounted on a first substrate; and

a second dual-band monopole planar antenna mounted on a second substrate;

wherein the first dual-band monopole planar antenna and the second dual-band monopole planar antenna each comprises;

a respective semi-elliptical shaped conductive disc having a respective symmetrical center axis;

a respective slot disposed in the respective semi-elliptical shaped conductive disc along a respective longitudinal axis substantially perpendicular to the respective symmetrical center axis to separate the respective semi-elliptical shaped conductive disc into a respective first conductive disc section and a respective second conductive disc section;

a respective conductive delay line having a respective first end feed point and a respective second end feed point disposed in the respective slot, wherein the respective first end feed point is conductively coupled to the respective first conductive disc section and the respective second end feed point is conductively coupled to the respective second conductive disc section; and

a respective disc feed point disposed in the respective first conductive disc section, wherein the respective disc feed point is configured to receive an electrical current from an electrical current source;

wherein the first substrate comprises a first slot opening disposed along the respective symmetrical center axis of the first dual-band monopole planar antenna;

wherein the second substrate comprises a second slot opening disposed along the respective symmetrical center axis of the second dual-band monopole planar antenna;

wherein the second slot opening of the second substrate receives the first substrate within the first slot opening to dispose the second dual-band monopole planar antenna substantially perpendicular to the first dual-band monopole planar antenna;

wherein the first dual-band monopole planar antenna and the second dual-band monopole planar antenna are electrically coupled along an intersection of the first substrate and the second substrate;

wherein the respective disc feed point of the first dual-band monopole planar antenna and the respective disc feed point of the second dual-band monopole planar antenna are electrically coupled to provide a common feed point for the dual-band antenna element; and

wherein the first dual-band monopole planar antenna and the second dual-band monopole planar antenna are configured to each generate a cylinder-shaped slant 45°

(slant-45) total electric field when the electrical current is received at the common feed point.

10. The dual-band antenna element of claim 9, wherein the first substrate and the second substrate are each comprised of circuit boards.

11. The dual-band antenna element of claim 10, further comprising an electrical feeding line coupled to the common feed point.

12. The dual-band antenna element of claim 11, further comprising a circular-shaped conductive disc electrically coupled to the first dual-band monopole planar antenna and the second dual-band monopole planar antenna on an opposite end from the common feed point, wherein the circular-shaped conductive disc is substantially perpendicular to the respective symmetrical center axis of the first dual-band monopole planar antenna and the second dual-band monopole planar antenna.

13. The dual-band antenna element of claim 9, wherein:

the respective conductive delay line in the first dual-band monopole planar antenna and the second dual-band monopole planar antenna is configured to receive the electrical current from the respective first conductive disc section at the respective first end feed point and provide the electrical current to the respective second conductive disc section at the respective second end feed point;

the respective first conductive disc section in the first dual-band monopole planar antenna and the second dual-band monopole planar antenna is configured to radiate electromagnetic energy on a first radio frequency (RF) band with a vertical radiation polarization in response to receiving the electrical current from the respective disc feed point; and

the respective second conductive disc section in the first dual-band monopole planar antenna and the second dual-band monopole planar antenna is configured to radiate electromagnetic energy on a second RF band lower than the first RF band with a slant-45 radiation polarization in response to receiving the electrical current from the respective second end feed point of the respective conductive delay line.

14. A multiple-input multiple-output (MIMO) antenna, comprising:

a planar mounting surface;

a first dual-band antenna element disposed on the planar mounting surface, wherein the first dual-band antenna element comprises at least one first dual-band monopole planar antenna having a first symmetrical center axis substantially perpendicular to the planar mounting surface and a first longitudinal axis substantially perpendicular to the first symmetrical center axis; and

a second dual-band antenna element disposed on the planar mounting surface, wherein the second dual-band antenna element comprises at least one second dual-band monopole planar antenna having a second symmetrical center axis substantially perpendicular to the planar mounting surface and a second longitudinal axis substantially perpendicular to the second symmetrical center axis;

wherein the second dual-band antenna element is disposed on the planar mounting surface such that the second longitudinal axis is substantially aligned with the first longitudinal axis in the first dual-band antenna element.

15. The MIMO antenna of claim 14, wherein the planar mounting surface is a conductive substrate.

16. The MIMO antenna of claim 15, wherein the at least one first dual-band monopole planar antenna and the at least one second dual-band monopole planar antenna each further comprise:

a respective semi-elliptical shaped conductive disc having a respective symmetrical center axis;

a respective slot disposed in the respective semi-elliptical shaped conductive disc along a respective longitudinal axis substantially perpendicular to the respective symmetrical center axis to separate the respective semi-elliptical shaped conductive disc into a respective first conductive disc section and a respective second conductive disc section;

a respective conductive delay line having a respective first end feed point and a respective second end feed point disposed in the respective slot, wherein the respective first end feed point is conductively coupled to the respective first conductive disc section and the respective second end feed point is conductively coupled to the respective second conductive disc section; and

a respective disc feed point disposed in the respective first conductive disc section, wherein the respective disc feed point is configured to receive an electrical current from an electrical current source.

17. The MIMO antenna according of claim 16, wherein:

the respective conductive delay line in the at least one first dual-band monopole planar antenna and the at least one second dual-band monopole planar antenna is configured to receive the electrical current from the respective first conductive disc section at the respective first end feed point and provide electrical current to the respective second conductive disc section at the respective second end feed point;

the respective first conductive disc section in the at least one first dual-band monopole planar antenna and the at least one second dual-band monopole planar antenna is configured to radiate electromagnetic energy on a first radio frequency (RF) band with a vertical radiation polarization in response to receiving the electrical current from the respective disc feed point; and

the respective second conductive disc section in the at least one first dual-band monopole planar antenna and the at least one second dual-band monopole planar antenna is configured to radiate electromagnetic energy on a second RF band lower than the first RF band with a slant-45 radiation polarization in response to receiving the electrical current from the respective second end feed point of the respective conductive delay line.

18. The MIMO antenna of claim 14, wherein:

the first dual-band antenna element is mounted on a first circuit board; and

the second dual-band antenna element is mounted on a second circuit board electrically decoupled from the first circuit board.

19. The MIMO antenna of claim 18, wherein:

the first circuit board comprises a first electrical feeding line coupled to a first common feed point exposed by the first dual-band antenna element; and

the second circuit board comprises a second electrical feeding line coupled to a second common feed point exposed by the second dual-band antenna element.

20. The MIMO antenna of claim 18, wherein the first dual-band antenna element and the second dual-band antenna element are electrically decoupled from each other.