Mobile wireless communications device having frequency selective grounding and related method

• US 8,417,300 B2
• Filed: 04/10/2012
• Issued: 04/09/2013
• Est. Priority Date: 08/26/2010
• Status: Active Grant

• Current Assignee: Malikie Innovations Limited (Key Patent Innovations Limited)
• Original Assignee: Blackberry Limited
• Inventors: Wong, Joshua Kwan Ho, Cooke, Adrian Matthew
• Primary Examiner(s): Bost, Dwayne
• Assistant Examiner(s): Johnson, Gerald
• Application Number:
  US13/442,968
• Publication Number:
  US 20120195011A1
• Time in Patent Office: 364 Days
• Field of Search: 455/575.1, 361/56, 361/752, 361/753
• US Class Current: 455/575.1
• CPC Class Codes: H01Q 1/243 with built-in antennas
• CPC Class Codes: H01Q 1/52 Means for reducing coupling between antennas; Means for reducing coupling between an antenna and another structure absorbing means H01Q17/00
• CPC Class Codes: H01Q 9/0421 with a shorting wall or a shorting pin at one end of the element H01Q9/0414 takes precedence
• CPC Class Codes: H01Q 9/0442 with particular tuning means
• CPC Class Codes: H04M 1/0277 for a printed circuit board assembly
• CPC Class Codes: Y10T 29/49128 Assembling formed circuit to base

Abstract

A mobile wireless communications device includes a portable housing having a metallic front housing forming a peripheral sidewall as a metallic ring. A circuit board is carried by the portable housing and forms a chassis ground plane. A wireless communications circuit is carried by a circuit board. An antenna circuit is carried by a circuit board and connected to the wireless communications circuit. A frequency selective grounding circuit is positioned at a selected grounding location at the chassis ground plane and metallic front housing and forms a harmonic trap that responds to a specific range of frequencies.

Claims

1. A mobile wireless communications device comprising:

a housing having a metallic side wall;

at least one circuit board carried by the housing and forming a chassis ground plane wherein the metallic side wall surrounds the circuit board;

a wireless communication circuit carried by a circuit board;

an antenna circuit carried by a circuit board and connected to the wireless communication circuit; and

a frequency selective grounding circuit positioned at a selected grounding location between the chassis grounding plane and the metallic side wall at a location where current changes direction and forming a harmonic trap that responds to a specific range of frequencies.

2. The mobile wireless communications device according to claim 1, wherein said frequency selective grounding circuit comprises at least one of a series resonator and parallel resonator having a value depending on bandwidth requirements.

3. The mobile wireless communications device according to claim 1, wherein said frequency selective grounding circuit has a programmable frequency response for grounding.

4. The mobile wireless communications device according to claim 3, wherein said frequency selective grounding circuit comprises a variable matching device.

5. The mobile wireless communications device according to claim 1, wherein said antenna circuit comprises a planar inverted F antenna circuit.

6. The mobile wireless communications device according to claim 1, wherein said wireless communication circuit comprises a cellular communication circuit.

7. The mobile wireless communications device according to claim 1, and further comprising a display and user input device both carried by the housing and connected to said wireless communication circuit.

8. A mobile wireless communications device comprising:

a housing having a metallic side wall;

at least one circuit board carried by the portable housing and forming a chassis ground plane wherein the metallic side wall surrounds the circuit board;

a wireless communication circuit carried by a circuit board;

an antenna circuit carried by a circuit board and connected to the wireless communication circuit; and

a frequency selective grounding circuit positioned at a selected grounding location between the chassis ground plane and the metallic side wall at a location where current changes direction and forming a harmonic trap that responds to a specific range of frequencies, wherein the frequency selective grounding circuit comprises a variable matching device.

9. The mobile wireless communications device according to claim 8, wherein said variable matching device is configured to change impedance at a grounding location.

10. The mobile wireless communications device according to claim 8, wherein said antenna circuit comprises a planar inverted F antenna circuit.

11. The mobile wireless communications device according to claim 8, wherein said wireless communication circuit comprises a cellular communication circuit.

12. The mobile wireless communications device according to claim 8, and further comprising a display and user input device both carried by the housing and connected to said wireless communication circuit.

13. A method of operating a mobile wireless communications device, wherein the device comprises a housing having a metallic side wall and at least one circuit board carried by the housing and forming a chassis ground plane wherein the metallic side wall surrounds the circuit board, a wireless communication circuit carried by a circuit board, and an antenna circuit carried by a circuit board and connected to the wireless communication circuit, the method comprising:

forming harmonic traps by positioning a frequency selective grounding circuit between a selected grounding location at the chassis grounding plane and the metallic side wall at a location where current changes direction that responds to a specific range of frequencies.

14. The method according to claim 13, wherein the frequency selective grounding circuit comprises at least one of a series resonator and parallel resonator having a value depending on bandwidth requirements.

15. The method according to claim 13, wherein the frequency selective grounding circuit has a programmable frequency response for grounding.

16. The method according to claim 13, wherein the frequency selective grounding circuit comprises a variable matching device.