Dual band antenna pair with high isolation

Patent metadata

Field	Value
Publication number	US-9437935-B2
Application number	US-201313779697-A
Country	US
Kind code	B2
Filing date	Feb 27, 2013
Priority date	Feb 27, 2013
Publication date	Sep 6, 2016
Grant date	Sep 6, 2016

Abstract

A dual band printed antenna pair operates simultaneously at both WLAN frequency bands (2.4 GHz/5 GHz). The antenna pair provides high isolation between both antennas while having an efficient over the air performance. The antenna pair achieve greater than 20 dB isolation at 2.4 GHz and 5 GHz band, while having antennas positioned in close proximity. The high isolation is accomplished using an orthogonal antenna configuration (exploiting orthogonal polarization) and a parasitic element to further enhance isolation at 2.4 GHz. The antenna pair and parasitic element are printed on a Printed Circuit Board (PCB) adding relatively little cost to the Radio Frequency (RF) interface. The PCB is then fixed on top of a metal chassis with the antenna keep out area overhanging a corner of the metal chassis to enhance performance.

First claim

What is claimed is:

1. An apparatus comprising:
a ground plane on a first side of a substrate;
a first planar metallic antenna on a second side of the substrate;
a second planar metallic antenna on the second side of the substrate, wherein the first planar metallic antenna and the second planar metallic antenna are configured to have orthogonal polarization; and
a planar metallic parasitic element disposed between the first and second planar metallic antennas on the second side of the substrate and configured to provide electrical isolation between the first and second planar metallic antennas, wherein the planar metallic parasitic element is in the same plane as the first planar metallic antenna and the second planar metallic antenna, said same plane being parallel to the ground plane, the planar metallic parasitic element is electrically connected to the ground plane.

2. The apparatus of claim 1 , wherein the first planar metallic antenna comprises a first feed point and the second planar metallic antenna comprises a second feed point, wherein the planar metallic parasitic element is configured to generate a first electric isolation field at the first feed point when the second planar metallic antenna is transmitting within a certain frequency range and is configured to generate a second electric isolation field at the second feed point when the first planar metallic antenna is transmitting within the certain frequency range.

3. The apparatus of claim 1 , wherein the first planar metallic antenna and the second planar metallic antenna are Planar inverted F-antennas (PIFA).

4. The apparatus of claim 3 , wherein the planar metallic parasitic element is formed in the shape of a capital letter L.

5. The apparatus of claim 1 , further comprising a metal chassis on which the substrate is mounted, the substrate having a first overhanging side extending beyond a first edge of the metal chassis, the substrate having a second overhanging side extending beyond a second edge of the metal chassis, wherein the first overhanging side of the substrate is adjacent to the second overhanging side of the substrate, wherein neither the first planar metallic antenna nor the second planar metallic antenna reside over metal.

6. The apparatus of claim 5 , wherein the first overhanging side of the substrate and the second overhanging side of the substrate form a 90 degree corner.

7. The apparatus of claim 1 , wherein the substrate comprises a printed circuit board.

8. A method of operating a multi-band wireless wide area network antenna apparatus, the method comprising:
transmitting a first signal at a first frequency in a first range of frequencies from a first planar metallic antenna, the first planar metallic antenna resides on a first side of a substrate, the substrate has a ground plane on a second side;
transmitting a second signal at a second frequency in a second range of frequencies from a second planar metallic antenna while transmitting from the first planar metallic antenna, the second planar metallic antenna resides on the first side of the substrate, the second signal transmitting orthogonal polarization to the first signal; and
generating currents through a planar metallic parasitic element that resides on the first side of the substrate between the first planar metallic antenna and the second planar metallic antenna, the currents generated in response to the first signal, the currents causing the planar metallic parasitic element to create an electric field that provides electrical isolation between the first and second planar metallic antennas, wherein the planar metallic parasitic element is in the same plane as the first planar metallic antenna and the second planar metallic antenna, said same plane being parallel to the ground plane, the planar metallic parasitic element is electrically connected to the ground plane.

9. The method of claim 8 , wherein the first planar metallic antenna comprises a first feed point and the second planar metallic antenna comprises a second feed point, the generating the currents through the planar metallic parasitic element comprises generating the electric isolation field at the second feed point when the first planar metallic antenna is transmitting within a certain frequency range.

10. The method of claim 9 , further comprising:
generating currents through the planar metallic parasitic element when the second planar metallic antenna is transmitting within the certain frequency range to cause an isolation field at the first feed point.

11. The method of claim 8 , wherein the first planar metallic antenna comprises a first feed point and the second planar metallic antenna comprises a second feed point, the generating the currents through the planar metallic parasitic element causes an electric field that combines destructively with an electric field of the first planar metallic antenna to minimize a resultant electric field in the second feed point.

12. The method of claim 11 , further comprising:
generating currents through the planar metallic parasitic element when the second planar metallic antenna is transmitting the second signal to cause an isolation field at the first feed point.

13. The method of claim 12 , wherein the first range of frequencies include frequencies between 2.41 GHz and 2.48 GHz and the second range of frequencies between 5.17 GHz and 5.82 GHz.

14. The method of claim 8 , wherein the substrate is mounted on a metal chassis, the substrate having a first overhanging side extending beyond a first edge of the metal chassis, the substrate having a second overhanging side extending beyond a second edge of the metal chassis, wherein the first overhanging side of the substrate is adjacent to the second overhanging side of the substrate, wherein neither the first planar metallic antenna nor the second planar metallic antenna reside over metal.

15. An apparatus comprising:
a printed circuit board having a first major side and a second major side;
a ground plane on the first major side of the printed circuit board;
a first metallic microstrip antenna on the second major side of the printed circuit board, the first metallic microstrip antenna configured to radiate a first signal in a first range of frequencies;
a second metallic microstrip antenna on the second major side of the printed circuit board, the second metallic microstrip antenna configured to radiate a second signal in a second range of frequencies, the second signal radiates orthogonal to the first signal; and
a planar metallic parasitic element disposed between the first and second metallic microstrip antennas on the second side of the printed circuit board and configured to provide electrical isolation between the first and second metallic microstrip antennas, wherein the planar metallic parasitic element is in the same plane as the first metallic microstrip antenna and the second metallic microstrip antenna, said same plane being parallel to the ground plane, the planar metallic parasitic element is electrically connected to the ground plane.

16. The apparatus of claim 15 , wherein the first metallic microstrip antenna comprises a first feed point, wherein the second metallic microstrip antenna comprises a second feed point, wherein the planar metallic parasitic element is configured to:
generate an electrical isolation field at the second feed point in response to the first metallic microstrip antenna radiating the first signal.

17. The apparatus of claim 16 , wherein the planar metallic parasitic element is further configured to:
generate an electrical isolation fi

Assignees

• Microsoft Corp
• Microsoft Technology Licensing Llc

Inventors

• Deluis Javier R
• Mahanfar Alireza
• Shewan Benjamin
• Casebolt Mark
• Reents Jeff

Classifications

• H01Q21/24

  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 title

• H01Q1/521

  reducing the coupling between adjacent antennas · CPC title

• H01Q21/28 Primary

  Combinations of substantially independent non-interacting antenna units or systems {(multiple beam H01Q25/00)} · CPC title