Multiple antenna assembly utilizing electro band gap isolation structures

• US 8,816,921 B2
• Filed: 04/27/2011
• Issued: 08/26/2014
• Est. Priority Date: 04/27/2011
• Status: Expired due to Fees

• Current Assignee: Blackberry Limited
• Original Assignee: Blackberry Limited
• Inventors: Ayatollahi, Mina
• Primary Examiner(s): TRAIL, ALLYSON NEEL
• Application Number:
  US13/095,256
• Publication Number:
  US 20120274522A1
• Time in Patent Office: 1,217 Days
• Field of Search: 343/745, 343/702, 343/601
• US Class Current: 343/745
• CPC Class Codes: H01Q 1/243 with built-in antennas
• CPC Class Codes: H01Q 1/521 reducing the coupling between adjacent antennas
• CPC Class Codes: H01Q 13/10 Resonant slot antennas
• CPC Class Codes: H01Q 17/00 Devices for absorbing waves radiated from an antenna; Combinations of such devices with active antenna elements or systems
• CPC Class Codes: H01Q 17/007 with means for controlling the absorption

Abstract

A multiple antenna assembly with high isolation between the antennas is disclosed. The assembly includes a dielectric substrate with a ground plane and first and second antennas thereon. One or more metal-dielectric isolation structures are on the substrate at locations at which an electric current is present that has a current density greater than a predefined threshold. Each metal-dielectric isolation structure resonates at a given frequency that inhibits mutual signal coupling between the first and second antennas. Various configurations, such as concentric ring patterns, for the metal-dielectric isolation structures are disclosed. A device can be provided to dynamically tune the given frequency of the metal-dielectric isolation structures to correspond to radio frequency signals emitted by the first and second antennas.

Claims

1. An antenna assembly for a wireless communication device comprising:

a substrate of dielectric material and having a first surface and a second surface on opposite sides of the substrate;

a ground plane formed by a layer of electrically conductive material on the first surface;

a first radiating element disposed on the substrate;

a second radiating element disposed on the substrate and spaced apart from the first radiating element; and

at least one metal-dielectric isolation structure supported on the substrate between the first and second radiating elements at positions only at which an electric current is present that has a current density greater than a predefined threshold, wherein each metal-dielectric isolation structure resonates at a given frequency that inhibits mutual signal coupling between the first and second radiating elements.

2. The antenna assembly as recited in claim 1 wherein each at least one metal-dielectric isolation structure comprises a pattern of slots in the layer of electrically conductive material.

3. The antenna assembly as recited in claim 1 wherein each at least one metal-dielectric isolation structure comprises a pattern of metal on the second surface of the substrate.

4. The antenna assembly as recited in claim 1 wherein each at least one metal-dielectric isolation structure comprises a pair of concentric rings each having a gap.

5. The antenna assembly as recited in claim 4 wherein the gap of one ring is diametrically opposite to the gap of the other ring and is oriented 180°

with respect to the gap of the other ring.

6. The antenna assembly as recited in claim 4 wherein the pair of concentric rings are either circular or rectilinear.

7. The antenna assembly as recited in claim 4 further comprising a switch for selectively creating an electrical path between the pair of concentric rings that alters the given frequency of the at least one metal-dielectric structure.

8. The antenna assembly as recited in claim 1 wherein each at least one metal-dielectric isolation structure comprises a rectilinear ring within which is an element shaped like a Jerusalem cross.

9. The antenna assembly as recited in claim 1 wherein the predefined threshold is half of a maximum current density occurring at any place between the first and second radiating element.

10. The antenna assembly as recited in claim 1 further comprising a device for dynamically varying the given frequency of the at least one metal-dielectric isolation structure.

11. The antenna assembly as recited in claim 10, wherein the device for dynamically varying the given frequency of the at least one metal dielectric structure is a variable tuning circuit comprising a capacitor.

12. The antenna assembly as recited in claim 1, wherein the at least one metal-dielectric structure comprises a switch.

13. The antenna assembly as recited in claim 1 further comprising a layer of liquid crystal polymer on the substrate adjacent to the at least one metal-dielectric isolation structure for dynamically varying the given frequency at which the at least one metal-dielectric isolation structure resonates.

14. The antenna assembly as recited in claim 1 wherein there are a plurality of metal-dielectric isolation structures;

and further comprising a separate inductive-capacitive lumped element network between adjacent ones of the plurality of metal-dielectric isolation structures for dynamically varying the given frequency.

15. An antenna assembly for a wireless communication device comprising:

a substrate of dielectric material and having a first surface and a second surface on opposite sides of the substrate;

a ground plane formed by a layer of electrically conductive material on the first surface;

a first radiating element disposed on the substrate;

a second radiating element disposed on the substrate and spaced apart from the first radiating element; and

a plurality of metal-dielectric isolation structures forming a non-periodic array on the substrate, wherein each metal-dielectric isolation structure resonates at a given frequency that inhibits mutual signal coupling between the first and second radiating elements.

16. The antenna assembly as recited in claim 15 wherein each of the plurality of metal-dielectric isolation structures on the substrate are at a location where an electric current is present that has a current density greater than a predefined threshold.

17. The antenna assembly as recited in claim 16 wherein the predefined threshold is half of a maximum current density occurring at any place between the first and second radiating elements.

18. The antenna assembly as recited in claim 15 wherein each at least one metal-dielectric isolation structure comprises a pair of either circular or rectilinear concentric rings, each having a gap.

19. The antenna assembly as recited in claim 18 wherein the gap of one ring is diametrically opposite to the gap of the other ring and is oriented 180°

with respect to the gap of the other ring.

20. The antenna assembly as recited in claim 18 further comprising a switch for selectively creating an electrical path between the pair of concentric rings that alters the given frequency of the at least one metal-dielectric structure.

21. The antenna assembly as recited in claim 15 wherein each at least one metal-dielectric isolation structure comprises a rectilinear ring within which is an element shaped like a Jerusalem cross.

22. The antenna assembly as recited in claim 15 further comprising a device for varying the given frequency of the at least one metal-dielectric isolation structure.

23. The antenna assembly as recited in claim 15 further comprising a layer of liquid crystal polymer on the substrate adjacent to the at least one metal-dielectric isolation structure for dynamically varying the given frequency at which the at least one metal-dielectric isolation structure resonates.

24. The antenna assembly as recited in claim 15 wherein there are a plurality of metal-dielectric isolation structures;

and further comprising a separate inductive-capacitive lumped element network between adjacent ones of the plurality of metal-dielectric isolation structures for dynamically varying the given frequency.