Loop antenna assembly for telecommunication devices

• US 6,236,368 B1
• Filed: 04/22/1999
• Issued: 05/22/2001
• Est. Priority Date: 09/10/1997
• Status: Expired due to Term

• Current Assignee: Tyco Electronics Logistics AG (TE Connectivity Limited)
• Original Assignee: Rangestar International Corp
• Inventors: Johson, Greg
• Primary Examiner(s): Le, Hoanganh
• Assistant Examiner(s): Alemu, Ephrem
• Application Number:
  US09/296,231
• Time in Patent Office: 761 Days
• Field of Search: 343/702, 343/866, 343/741, 343/700.MS, 343/855
• US Class Current: 343/702
• CPC Class Codes: H01Q 1/243 with built-in antennas
• CPC Class Codes: H01Q 7/00 Loop antennas with a substantially uniform current distribution around the loop and having a directional radiation pattern in a plane perpendicular to the plane of the loop

Abstract

A loop directive antenna having improved front-to-back ratio and gain for given input power levels assembly for a hand-held radio frequency transceiver, such as a cellular telephone or PCS device operating in the 800-900 or 1850-1990 MHz. frequency ranges, respectively, is provided by the present invention. The loop directive antenna assembly consists of a main loop antenna conductor disposed upon a dielectric element. The main loop antenna conductor and dielectric element are maintained a predetermined distance away from a ground plane, which may be the circuit board or other conductive element. The main loop antenna conductor may include a variety of feedpoint orientations to provide alternative polarizations of the transmitted signal. The ground plane may be a portion of the printed circuit board of the device, a conductive part of the device housing, the battery pack of the device, or a separate conductive panel.

Claims

1. An antenna assembly for a hand-held radio frequency transceiver having a signal conductor and a ground conductor, said antenna assembly comprising:

a conductive ground plane element;

a dielectric substrate element having a first surface, said first surface maintained a predetermined distance away from the conductive ground plane element; and

a loop element disposed upon the first surface of the dielectric substrate element, said loop element having first and second ends disposed generally opposite each other, the signal conductor of the transceiver being coupled proximate said first end, and the ground conductor being coupled proximate said second end, said loop element having a plurality of side elements each having an associated width presented on the dielectric substrate, and wherein the widths of at least a pair of said plurality of side elements are substantially different.

2. The antenna assembly according to claim 1 wherein at least a portion of the ground plane element is defined by either a printed circuit board or a battery pack or a conductive panel of the transceiver.

3. The antenna assembly according to claim 1 wherein the dielectric substrate element has a dielectric constant of between 1 and 10.

4. The antenna assembly according to claim 3 wherein the dielectric substrate element has a dielectric constant between approximately 9 and 10.

5. The antenna assembly according to claim 1 wherein the loop element is generally square in shape having a top side, a bottom side, a right side, and a left side, and said top side and said bottom side having equal widths, and said right side and said left side having equal widths.

6. The antenna assembly according to claim 5 wherein the top side width and right side width are related by a ratio of approximately 2:

1.

7. The antenna assembly according to claim 1 wherein the loop element has a length of approximately one wavelength of a frequency selected within an operating range of frequencies of the transceiver.

8. The antenna assembly according to claim 1 wherein the dielectric substrate element is substantially planar in form.

9. The antenna assembly according to claim 1 wherein the antenna assembly is disposed near a top portion of the transceiver during use.

10. The antenna assembly according to claim 1 wherein the predetermined distance of the first surface of the dielectric substrate element to the ground plane element is approximately between 0.05 to 0.30 times a wavelength of a frequency selected within an operating range of frequencies of the transceiver.

11. The antenna assembly according to claim 1 wherein the dielectric substrate element is disposed upon at least a portion of the conductive ground plane element.

12. A portable radio frequency communication device comprising:

an electrical apparatus having a signal conductor and an associated ground conductor and a ground plane element;

a loop element having generally opposite ends disposed relative to the ground plane element, said loop element being electrically coupled at one end to the signal conductor and at the other end to the ground conductor, said loop element having a plurality of side elements, each of said side elements having an associated width, and at least a pair of said plurality of side elements having different widths; and

a dielectric substrate element disposed between the loop element and at least a portion of the ground plane element.

13. The portable radio frequency communication device according to claim 12 wherein the loop element is disposed upon the dielectric substrate element.

14. The portable radio frequency communication device according to claim 12 wherein the dielectric substrate element is substantially planar in form.

15. The portable radio frequency communication device according to claim 12 further comprising:

a parasitic element disposed away from the active loop conductor element and operatively coupled to the loop element.

16. A radio frequency communication device, said communication device comprising:

a printed circuit board having a radio frequency circuit having a signal conductor and an associated ground conductor and a ground plane;

a loop radiating element having a first end and a second end, said loop radiating element being operatively coupled to the signal conductor proximate the first end and to the ground conductor proximate the second end, said loop radiating element having a length between the first end and the second end, said radiating loop element having a plurality of side elements each having an associated width, and wherein the widths of at least a pair of said plurality of side elements are different; and

a dielectric substrate element disposed between the loop radiating element and at least a portion of the ground plane.

17. The communication device according to claim 16 wherein the loop radiating element is disposed upon the dielectric substrate element.

18. The communication device according to claim 16 wherein the dielectric substrate element is substantially planar in form.

19. The communication device according to claim 16 wherein the dielectric substrate element has a dielectric constant of between 9 and 10.

20. The radio frequency communication device according to claim 16 further comprising:

a parasitic element disposed away from the loop radiating element and being operatively coupled to the conductive loop radiating element.

21. A transceiver comprising:

a radio frequency circuit;

a coax feedline having a first and second end and a predetermined diameter, each end having an associated first and second conductor, said fist and second conductor of the first end being operatively coupled to the radio frequency circuit;

a conductive ground plane circuit;

a dielectric substrate element having a first surface, said first surface maintained a predetermined distance away from the conductive ground plane element, said dielectric substrate having an aperture sized in relation to the predetermined diameter to pass both the first and second conductors of the second end of the coax feedline; and

a loop element disposed upon the first surface of the dielectric substrate element, said loop element having opposed first and second ends and an area intermediate said first and second ends, said intermediate area containing the aperture of the dielectric substrate, said first and second ends of the loop being respectively coupled to the first and second conductors associated with the second end of the coax feedline, said loop element having a plurality of side elements each having an associated width presented on the dielectric substrate, and wherein the widths of at least a pair of said plurality of side elements are different.

22. The antenna assembly according to claim 21 wherein the loop element includes a plurality of side elements, and at least a pair of said plurality of side elements having different widths.

23. The antenna assembly according to claim 21 wherein the ground plane element is defined at least in part by the radio frequency circuit.

24. A conformal antenna assembly for a radio frequency communication device providing a signal conductor and an associated ground conductor and having a housing, said housing having a formed surface, said conformal antenna assembly comprising:

a ground plane element;

a dielectric substrate element having a conformed surface disposed between the ground plane element and the formed surface of the housing and being related to the formed surface of the housing, and

a loop radiating element disposed upon the conformed surface of the dielectric substrate element, said loop radiating element defining a pair of ends and being coupled proximate one end to the signal conductor, and being coupled proximate the other end to the ground conductor, said loop radiating element having a plurality of side elements each having an associated width presented on the dielectric substrate, and wherein the widths of at least a pair of said plurality of side elements a different.

25. The conformal antenna assembly of claim 24 wherein the formed surface of the communication device and the conformed surface of the dielectric substrate element are both approximately cylindrical in profile.

26. The conformal antenna assembly of claim 24 wherein the ground plane element is defined at least in part by a printed circuit board or a battery pack or a conductive panel of the communication device.