Mobile wireless communications device having frequency selective grounding and related method
View Patent ↗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.
1. A mobile wireless communications device comprising:
a housing comprising a front and an electrically conductive side wall extending from the front;
at least one circuit board carried by the housing and defining a ground plane surrounded by the electrically conductive side wall;
an antenna carried by the at least one circuit board; and
a frequency selective grounding circuit coupled at a grounding location between the ground plane and the electrically conductive side wall at a location where current changes direction.
2. The mobile wireless communications device according to claim 1 , wherein the frequency selective ground circuit defines a harmonic trap at a specific range of frequencies.
3. The mobile wireless communications device according to claim 1 , wherein the frequency selective grounding circuit comprises a series resonator.
4. The mobile wireless communications device according to claim 1 , wherein the frequency selective grounding circuit comprises a parallel resonator.
5. The mobile wireless communications device according to claim 1 , wherein the frequency selective grounding circuit has a programmable frequency response.
6. The mobile wireless communications device according to claim 1 , wherein the frequency selective grounding circuit comprises a variable matching device.
7. The mobile wireless communications device according to claim 1 , wherein the antenna comprises a planar inverted F antenna.
8. The mobile wireless communications device according to claim 1 , wherein the at least one circuit board comprises a wireless communication circuit.
9. The mobile wireless communications device according to claim 1 , wherein the at least one circuit board comprises a cellular communication circuit.
10. The mobile wireless communications device according to claim 1 , and further comprising a display and user input device both carried by the housing and coupled to the at least one circuit board.
11. A mobile wireless communications device comprising:
a housing comprising a front and an electrically conductive side wall extending from the front;
at least one circuit board carried by the housing and defining a ground plane surrounded by the electrically conductive side wall;
an antenna carried by the at least one circuit board; and
a variable matching device coupled at a location between the ground plane and the electrically conductive side wall at a location where current changes direction.
12. The mobile wireless communications device according to claim 11 , wherein the variable matching device is configured to change impedance at a grounding location.
13. The mobile wireless communications device according to claim 11 , wherein the antenna comprises a planar inverted F antenna.
14. The mobile wireless communications device according to claim 11 , wherein the at least one circuit board comprises a wireless communication circuit.
15. The mobile wireless communications device according to claim 11 , wherein the at least one circuit board comprises a cellular communication circuit.
16. The mobile wireless communications device according to claim 11 , and further comprising a display and user input device both carried by the housing and coupled to the at least one circuit board.
17. A method for making a mobile wireless communications device comprising:
positioning at least one circuit board within a housing and defining a ground plane surrounded by an electrically conductive side wall of the housing, and with an antenna carried by the at least one circuit board; and
coupling a frequency selective grounding circuit at a grounding location between the ground plane and the electrically conductive side wall at a location where current changes direction.
18. The method according to claim 17 , wherein the frequency selective ground circuit defines a harmonic trap at a specific range of frequencies.
19. The method according to claim 17 , wherein the frequency selective grounding circuit comprises a series resonator.
20. The method according to claim 17 , wherein the frequency selective grounding circuit comprises a parallel resonator.
21. The method according to claim 17 , wherein the frequency selective grounding circuit has a programmable frequency response, and further comprising programming the programmable frequency response.
22. The method according to claim 17 , wherein the frequency selective grounding circuit comprises a variable matching device.
23. The method according to claim 17 , wherein the antenna comprises a planar inverted F antenna.
24. The method according to claim 17 , wherein the at least one circuit board comprises a cellular communication circuit.