Antenna system using capacitively coupled compound loop antennas with antenna isolation provision

• US 9,496,614 B2
• Filed: 04/15/2014
• Issued: 11/15/2016
• Est. Priority Date: 04/15/2014
• Status: Active Grant

• Current Assignee: DockOn AG
• Original Assignee: DockOn AG
• Inventors: Bringuier, Jonathan Neil, Orsi, Ryan James, Foster, Matthew Robert
• Primary Examiner(s): Nguyen, Hoang V
• Assistant Examiner(s): TRAN, HAI V
• Application Number:
  US14/253,678
• Publication Number:
  US 20150295311A1
• Time in Patent Office: 945 Days
• Field of Search: 343/729, 343/700.MS, 343/702
• US Class Current: 1/1
• CPC Class Codes: H01Q 1/521 reducing the coupling between adjacent antennas
• CPC Class Codes: H01Q 21/30 Combinations of separate antenna units operating in different wavebands and connected to a common feeder system
• CPC Class Codes: H01Q 5/307 Individual or coupled radiating elements, each element being fed in an unspecified way
• CPC Class Codes: H01Q 5/371 Branching current paths
• 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 9/0407 Substantially flat resonant element parallel to ground plane, e.g. patch antenna dipole H01Q9/285; monopole H01Q9/40

Abstract

An antenna system is provided, including a first antenna, a second antenna, a ground plane, and a resonant isolator coupled to the first and second antennas. Each of the antennas is configured to be a capacitively-coupled compound loop antenna, and the resonant isolator is configured to provide isolation between the two antennas at resonance. The two antennas may be symmetrical or asymmetrical and include a first element that emits a magnetic field and a second element that generates an electrical field that is orthogonal to the magnetic field. The radiating element of the second element may be capacitively coupled to the remainder of the second element. The resonate isolator may be comprised of a single conductive element or two conductive elements that are capacitively coupled.

Claims

1. An antenna system, comprising:

a first layer including at least a pair of antennas having a first antenna and a second antenna, the first layer further including a first ground plane; and

a second layer including a resonant isolator and a second ground plane, the resonant isolator being a conductive element that is placed on or within the second layer separate from the second ground plane, the resonant isolator having a first end portion and a second end portion, the resonant isolator being configured to electromagnetically isolate the first antenna from the second antenna at a resonance, the first end portion being coupled to the first antenna by a first via and the second end portion being coupled to the second antenna by a second via, the first via and the second via being formed vertical to the first layer and the second layer and separated from the first and second ground planes; and

wherein each of the first antenna and the second antenna include;

a first element that is coupled to a current feed point at a first end point and is shorted to the first ground plane at a second end point, the first element emitting a magnetic field; and

a second element that is coupled to the first element at an electrical length of substantially 90 degrees or an odd multiple of substantially 90 degrees from the feed point, the second element generating an electrical field substantially orthogonal to the magnetic field.

2. The antenna system of claim 1, wherein the first element comprises a first section, a second section and a gap formed between the first section and the second section, and wherein the first section and the second section are capacitively coupled through the gap.

3. The antenna system of claim 1, wherein the second element comprises a first section, a second section and a gap formed between the first section and the second section, and wherein the first section and the second section are capacitively coupled through the gap.

4. The antenna system of claim 1, wherein the resonant isolator has an electrical length of substantially 90 degrees or an odd multiple of substantially 90 degrees that generates a forward wave and a reflective wave having a phase offset resulting in an open circuit at resonance when the forward and backward waves are combined and thereby providing isolation between the first antenna and the second antenna.

5. The antenna system of claim 1, wherein the resonant isolator has an electrical length that provides one of a substantially 90 degree phase delay or an odd multiple of a substantially 90 degree phase delay between the first antenna and the second antenna.

6. The antenna system of claim 1, wherein the first via is coupled to the current feed point of the first antenna where a current value is maximum and the second via is coupled to the current feed point of the second antenna where the current value is maximum.

7. The antenna system of claim 1, wherein the first layer includes N pairs of antennas and the second layer includes N resonant isolators, wherein one resonant isolator among the N resonant isolators corresponds to each pair of antennas among the N pairs of antennas.

8. The antenna system of claim 1, wherein the antenna system is a multi-band antenna system and the resonant isolator is configured to isolate the first antenna from the second antenna at each resonance of the multi-band antenna system.

9. The antenna system of claim 1, wherein the resonant isolator includes a conductive line coupling the first end portion to the second end portion.

10. The antenna system of claim 1, wherein the resonant isolator includes a gap formed between the first end portion and the second end portion, and wherein the first end portion and the second end portion are capacitively coupled through the gap.

11. An antenna system comprising:

a first pair of antennas including a first antenna and a second antenna;

a ground plane; and

a resonant isolator having a first end portion coupled to the first antenna and a second end portion coupled to the second antenna, the resonant isolator being a conductive element placed separately from the ground plane, the resonant isolate being configured to electromagnetically isolate the first antenna from the second antenna at resonance,

wherein each of the first antenna and the second antenna comprises;

a first element that is coupled to a current feed point at a first end point and is shorted to the ground plane at a second end point, the first element emitting a magnetic field;

a second element that is coupled to the first element at an electrical length of substantially 90°

or an odd multiple of substantially 90 degrees from the feed point, the second element generating an electrical field substantially orthogonal to the magnetic field.

12. The antenna system of claim 11, wherein the first element comprises a first section, a second section and a gap formed between the first section and the second section, and wherein the first section and the second section are capacitively coupled through the gap.

13. The antenna system of claim 11, wherein the second element comprises a first section, a second section and a gap formed between the first section and the second section, and wherein the first section and the second section are capacitively coupled through the gap.

14. The antenna system of claim 11, wherein the resonant isolator has an electrical length of substantially 90 degrees or an odd multiple of substantially 90 degrees that generates a forward wave and a reflective wave having a phase offset resulting in an open circuit at resonance when the forward and backward waves are combined and thereby providing isolation between the first antenna and the second antenna.

15. The antenna system of claim 11, wherein the resonant isolator has an electrical length that provides one of a substantially 90 degree phase delay or an odd multiple of a substantially 90 degree phase delay between the first antenna and the second antenna.

16. The antenna system of claim 11, wherein the first end portion is coupled to the first antenna at the current feed point of the first antenna where a current value is maximum and the second end portion is coupled to the current feed point of the second antenna where the current value is maximum.

17. The antenna system of claim 11, wherein the resonant isolator includes a conductive line coupling the first end portion to the second end portion.

18. The antenna system of claim 11, wherein the resonant isolator includes a gap formed between the first end portion and the second end portion, and wherein the first end portion and the second end portion are capacitively coupled through the gap.

19. The antenna system of claim 11, wherein the first element is a loop element and the second element is a radiating monopole element.

20. The antenna system of claim 19, wherein the radiating element operates at a first frequency, and wherein first element further includes a second radiating element operating at a second frequency substantially different from the first frequency.

21. The antenna system of claim 11, further comprising N pairs of antennas and N resonant isolators, wherein one resonant isolator among the N resonant isolators corresponds to each pair of antennas among the N pairs of antennas.

22. The antenna system of claim 11, wherein the antenna system is a multi-band antenna system and the resonant isolator is configured to isolate the first antenna from the second antenna at each resonance of the multi-band antenna system.