DISTRIBUTED MULTIBAND ANTENNA AND METHODS

• US 20110260939A1
• Filed: 04/21/2010
• Published: 10/27/2011
• Est. Priority Date: 04/21/2010
• Status: Active Grant

• Current Assignee: Cantor Fitzgerald Securities (Cantor Fitzgerald, L.P.)
• Original Assignee: Cantor Fitzgerald Securities (Cantor Fitzgerald, L.P.)
• Inventors: Annamaa, Petteri, Raappana, Ari, Korva, Heikki
• Granted Patent: US 9,406,998 B2
• Time in Patent Office: Days
• US Class Current: 343/725
• CPC Class Codes: H01Q 1/243 with built-in 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 5/357 using a single feed point
• CPC Class Codes: H01Q 5/378 Combination of fed elements with parasitic elements
• 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 9/42 with folded element, the folded parts being spaced apart a small fraction of the operating wavelength

Abstract

A distributed multiband antenna intended for radio devices, and methods for designing manufacturing the same. In one embodiment, a planar inverted-F antenna (PIFA) configured to operate in a high-frequency band, and a matched monopole configured to operate in a low-frequency band, are used within a handheld mobile device (e.g., cellular telephone). The two antennas are placed on substantially opposing regions of the portable device. The use of a separate low-frequency antenna element facilitates frequency-specific antenna matching, and therefore improves the overall performance of the multiband antenna. The use of high-band PIFA reduces antenna volume, and enables a smaller device housing structure while also reducing signal losses in the high frequency band. These attributes also advantageously facilitate compliance with specific absorption rate (SAR) tests; e.g., in the immediate proximity of hand and head “phantoms” as mandated under CTIA regulations. Matching of the low-frequency band monopole antenna is further described.

Claims

1. A multiband antenna assembly having lower and an upper operating frequency bands, said assembly for use in a mobile radio device, said assembly comprising:

a ground plane having a first and a second substantially opposing edges;

a monopole antenna configured to operate in a first frequency band and being disposed proximate to said first edge;

a planar inverted-F antenna (PIFA) configured to operate in a second frequency band and being disposed proximate to said second edge; and

a feed apparatus configured to feed said monopole antenna and said PIFA elements;

wherein said monopole antenna further comprises;

a radiator element formed in a plane substantially perpendicular to said ground plane;

a non-conductive slot formed within said radiator element; and

a matching circuit comprising;

a feed point;

a ground;

a stripline coupled from said ground to said feed point;

a tuning capacitor coupled to said ground and said stripline; and

a feed pad coupled to said stripline via an inductor;

wherein said feed pad is further coupled to said radiator element; and

wherein said PIFA further comprises;

a first planar radiator formed substantially parallel to said ground plane;

a parasitic planar radiator formed substantially coplanar to said first planar radiator;

a non-conductive slot formed inside within said first planar element;

a first feed point coupled from said first planar radiator element to said feed apparatus;

a ground point coupled from first planar radiator element to said ground plane; and

a parasitic feed point coupled from said parasitic feed point to said ground plane.

2. The antenna assembly of claim 1, wherein center frequency of said lower frequency band is below 1600 MHz and center frequency of said upper frequency band is above 1700 MHz.

3. The antenna assembly of claim 2, wherein center said lower frequency band further comprises a global system for mobile communications (GSM) 900 band and said upper frequency band comprises GSM1800 band.

4. The antenna assembly of claim 3, wherein said lower frequency band comprises a global positioning system (GPS) band and said upper frequency band comprises GSM1900 frequency band.

5. Antenna apparatus, comprising:

a ground plane having a first and a second substantially opposing ends;

a first antenna element operable in a first frequency band and disposed proximate to said first end;

a matching circuit coupled to said first antenna element;

a second antenna element configured to operate in an second frequency band and disposed proximate to said second end; and

feed apparatus operably coupled to said first and said second antenna elements.

6. The apparatus of claim 5, wherein said first antenna element comprises a monopole antenna structure, and said first band is lower in frequency than said second band.

7. The apparatus of claim 6, wherein said matching circuit further comprises:

a feed point;

a ground;

a stripline coupled from said ground to said feed point; and

a feed pad coupled to said stripline via a coupling circuit.

8. The apparatus of claim 7, wherein said monopole antenna further comprises:

a capacitive element coupled between said ground and said stripline; and

a radiator element formed in a plane substantially perpendicular to said ground plane;

wherein said feed pad is further coupled to said radiator element.

9. The apparatus of claim 5, wherein said second antenna element comprises a planar inverted-F antenna (PIFA) structure.

10. The apparatus of claim 9, wherein said PIFA further comprises:

a first planar radiator formed substantially parallel to said ground plane;

a parasitic planar radiator formed substantially coplanar to said first planar radiator;

a non-conductive slot formed inside within said first planar element;

a first feed point coupled from said first planar radiator element to said feed apparatus;

a ground point coupled to first planar radiator element and said ground plane; and

a parasitic feed point coupled to said parasitic feed point and said ground plane.

11. The apparatus of claim 5, wherein a center frequency of said first frequency is below 1600 MHz, and a center frequency of said second frequency band is above 1700 MHz.

12. The apparatus of claim 11, wherein center said first frequency band comprises a Global System for Mobile Communications (GSM) 900 band, and said second frequency band comprises a GSM1800 band.

13. The apparatus of claim 5, wherein said first frequency band comprises a Global Positioning System (GPS) band, and said second frequency band comprises a WLAN frequency band of approximately 2.4 GHz.

14. The apparatus of claim 5, wherein said first and said second antenna comprise substantially different antenna types.

32. The assembly of claim 7, wherein said coupling element comprises an inductive circuit.

33. The assembly of claim 8, wherein said capacitive element is configured to effect tuning of antenna resonance to a first frequency band.

15. A mobile communications device having multiband antenna apparatus contained substantially therein, the device comprising:

an exterior housing;

a substrate disposed substantially within the housing;

a ground plane having a first and a second substantially opposing ends, at least a portion of the ground plane disposed on the substrate;

a first antenna element operable in a first frequency band and disposed proximate to said first end;

a matching circuit coupled to said first antenna element;

a second antenna element configured to operate in an second frequency band and disposed proximate to said second end;

feed apparatus operably coupled to said first and said second antenna elements; and

at least one radio frequency transceiver in operative communication with said feed apparatus.

16. The apparatus of claim 15, wherein said first antenna element comprises a monopole antenna structure, and said first band is lower in frequency than said second band.

17. The apparatus of claim 16, wherein said exterior housing is of the candy-bar type.

18. The apparatus of claim 16, wherein said exterior housing is of the flip-open type.

19. The apparatus of claim 15, wherein said first antenna element comprises a monopole-type antenna, and said second antenna element comprises a PIFA.

20. The apparatus of claim 19, wherein said monopole-type antenna is disposed substantially proximate to a microphone-bearing end of said device, and said PIFA is disposed substantially proximate to a speaker- or earpiece-bearing end of said device.

21. The apparatus of claim 15, wherein a center frequency of said first frequency is below 1600 MHz, and a center frequency of said second frequency band is above 1700 MHz.

22. The apparatus of claim 21, wherein center said first frequency band comprises a Global System for Mobile Communications (GSM) 900 band, and said second frequency band comprises a GSM1800 band.

23. The apparatus of claim 15, wherein said first frequency band comprises a Global Positioning System (GPS) band, and said second frequency band comprises a WLAN frequency band of approximately 2.4 GHz.

24. The apparatus of claim 16, wherein said first and said second antenna comprise substantially different antenna types.

25. A method of operating multi-band antenna assembly, the antenna comprising first, second, and third antenna radiating elements, and at least first, second, and third feed points, the method comprising:

selectively electrically coupling said first feed point to said first radiating element via a first circuit;

or

selectively electrically coupling said second feed point to said second radiating element via a second circuit; and

said third feed point to said third radiating element via a third circuit;

wherein the first and second circuits effect the antenna assembly to operate in a first frequency band; and

wherein the third circuit effect the antenna assembly to operate in a second frequency band.

26. The method of claim 25 further comprising the step of electrically matching the third radiating element to the second frequency band.

27. The method of claim 26, wherein matching comprises providing stripline configured to tune antenna resonance to the second frequency band.

28. The method of claim 25 further comprising the step of electrically isolating the first and the second radiating elements from the third radiating element.

29. An antenna assembly comprising:

a ground plane;

a matching circuit comprising;

a feed;

a ground;

a stripline coupled from said ground to said feed point;

a feed pad coupled to said stripline via a coupling element; and

a radiator element formed in a plane substantially perpendicular to said ground plane;

wherein said feed pad is further coupled to said radiator element.

30. The assembly of claim 29, wherein said matching circuit further comprises a capacitive element coupled from said ground to said stripline and configured to effect tuning of antenna resonance to a first frequency band.

31. The assembly of claim 29, wherein said coupling element comprises an inductive circuit.

34. A reduced-size mobile radio device operable in a lower and an upper frequency bands, said device comprising an exterior housing and a multiband antenna assembly, said antenna assembly comprising a rectangular ground plane having first and second substantially opposing regions, said mobile radio device being configured according to the method comprising:

placing a first antenna element configured to resonate in the upper frequency band proximate to a said first region; and

placing a second antenna element configured to resonate in the lower frequency band proximate to said second region;

wherein said first antenna element comprises a planar inverted-F antenna (PIFA); and

wherein the act of placing the first antenna element effects reduction of the exterior housing size in at least one dimension.