Tri-band antenna for digital multimedia broadcast (DMB) applications

• US 7,113,135 B2
• Filed: 06/08/2004
• Issued: 09/26/2006
• Est. Priority Date: 06/08/2004
• Status: Active Grant

• Current Assignee: SkyCross Co., Ltd.
• Original Assignee: SkyCross, Inc.
• Inventors: Caimi, Frank M., Jo, Young-Min
• Primary Examiner(s): Lee, Wilson
• Assistant Examiner(s): Ho, Binh Van
• Application Number:
  US10/863,809
• Publication Number:
  US 20050270238A1
• Time in Patent Office: 840 Days
• Field of Search: 343/702
• US Class Current: 343/702
• CPC Class Codes: H01Q 1/242 specially adapted for hand-held use
• CPC Class Codes: H01Q 1/243 with built-in antennas
• CPC Class Codes: H01Q 5/371 Branching current paths
• CPC Class Codes: H01Q 9/0414 in a stacked or folded configuration
• 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 9/30 with feed to end of elongated active element, e.g. unipole H01Q9/44 takes precedence
• CPC Class Codes: H01Q 9/40 Element having extended radiating surface

Abstract

A radio frequency transmitting and receiving apparatus comprising an antenna further comprising a plurality of antenna segments. Each segment exhibits a different electrical length and certain of the segments are capacitively coupled to establish a resonant frequency for each segment. In one embodiment, the certain segments comprise a plurality of concentric arcuate conductive elements connected to a signal terminal and a ground plane.

Claims

1. An antenna for receiving radio frequency signals, comprising:

a first resonant segment comprising first and second connected conductive strips a width of the first conductive strip bifurcated along a partial length thereof to form a first and a second bifurcated segment;

the first bifurcated segment extending from a plane of the first conductive strip and forming a second resonant segment;

the second bifurcated segment extending from the plane of the first conductive segment and forming a third resonant segment; and

wherein the first segment is resonant at a first frequency, the second segment is resonant at a second frequency and the third segment is resonant at a third frequency.

2. The antenna of claim 1 wherein the first frequency is lower than the second frequency and the second frequency is lower than the third frequency.

3. The antenna of claim 1 wherein the third resonant frequency is responsive to a distance between the first and the third resonant segments and a length of the third segment.

4. The antenna of claim 1 wherein the first resonant segment comprises the first and the second conductive strips and a bridging segment connecting the first and the second conductive strips, the first and the second conductive strips each comprising a curved conductive strip, the curved conductive strips substantially concentric and spaced-apart by a distance, and wherein the first resonant frequency is responsive to the distance and a length of the first resonant segment.

5. The antenna of claim 1 further comprising a signal terminal proximate an end of the first resonant segment.

6. The antenna of claim 5 wherein a length of the first segment comprises a distance between the signal terminal and an open end of the first segment, and a length of the third segment comprises a distance between the signal terminal and an open end of the third segment.

7. The antenna of claim 5 wherein a length of the second segment comprises a distance between a point spaced apart from the signal terminal and an open end of the second segment.

8. The antenna of claim 1 further comprising a conductive plate extending from a partial length of the first resonant segment.

9. The antenna of claim 1 further comprising a ground plane disposed proximate the first, the second and the third segments, wherein the second segment is conductively connected to the ground plane.

10. The antenna of claim 9 wherein the second segment comprises a reversed C-shaped segment, an upper leg of the shaped segment extending from a point spaced apart from a signal terminal proximate an end of the first resonant segment, and a lower leg of the shaped segment conductively connected to the ground plane.

11. The antenna of claim 1 wherein a parasitic capacitor is formed between each of the first, the second and the third segments, and wherein one or more of the first frequency, the second frequency and the third frequency are responsive to the parasitic capacitors.

12. The antenna of claim 11 wherein an electrical length of one or more of the first, the second and the third segments is responsive to the parasitic capacitors.

13. The antenna of claim 1 wherein the first, the second and the third segments are spaced apart forming parasitic capacitors between pairs of segments, and wherein one or more of the first frequency, the second frequency and the third frequency are responsive to the parasitic capacitors.

14. An antenna, comprising:

a first resonant element comprising a first conductive strip having a first width and shaped to form a boundary defining an interior region and an exterior region;

a second resonant element comprising a second conductive strip extending into the exterior region and further comprising an extension of a first portion of the first width from the first conductive strip;

a third resonant element comprising a third conductive strip extending through an opening defined in the boundary into the interior region and further comprising an extension of a second portion of the first width from the first conductive strip; and

wherein a plane of each of the second and the third conductive strips is different from a plane of the first conductive strip.

15. The antenna of claim 14 wherein a first antenna resonant frequency is responsive to an electrical length of the first element and capacitive coupling of the first element to the second and the third elements, and wherein a second antenna resonant frequency is responsive to an electrical length of the second element and capacitive coupling of the second element to the first and the third elements, and wherein a third antenna resonant frequency is responsive to an electrical length of the third element and capacitive coupling of the third element to the first and the second elements.

16. The antenna of claim 14 wherein the first resonant element comprises a laterally-facing U-shaped structure further comprising two substantially horizontal leg sections and a substantially vertical bridging section that together define an opening in the U-shaped structure, and wherein the third resonant element extends through the opening into the interior region.

17. The antenna of claim 14 wherein the first, second and third resonant elements are conductively connected and capacitively coupled.

18. The antenna of claim 14 further comprising a signal terminal for supplying a signal when the antenna is operative in a receiving mode.

19. The antenna of claim 18 wherein the first and the third resonant elements are conductively connected at the signal terminal.

20. The antenna of claim 14 wherein the second resonant element is conductively connected to the first resonant element spaced apart from the signal terminal.

21. The antenna of claim 14 wherein the second resonant element is conductively connected to a ground.

22. The antenna of claim 14 wherein the antenna is disposed over a ground plane to which the second resonant element is conductively connected.

23. The antenna of claim 14 wherein a resonant frequency of each of the first, the second and the third elements is responsive to an effective electrical length of the first, the second and the third elements, respectively.

24. A communications device for receiving radio frequency signals, comprising

a substrate having a ground region disposed thereon;

a plurality of device components disposed within an interior region of the communications device and defining a space envelope within the interior region;

an antenna shaped to fit within the space envelope, the antenna comprising;

a first resonant element shaped according to the space envelope to form a boundary defining an interior region and an exterior region;

a second resonant element disposed in the exterior region;

a third resonant element disposed in the interior region; and

wherein a first resonant frequency is responsive to an electrical length of the first element and capacitive coupling of the first element to the second and the third elements, and wherein a second antenna resonant frequency is responsive to an electrical length of the second element and capacitive coupling of the second element to the first and the third elements, and wherein a third antenna resonant frequency is responsive to an electrical length of the third element and capacitive coupling of the third element to the first and the second elements.

25. The antenna of claim 24 wherein the first resonant frequency is lower than the second resonant frequency and the second resonant frequency is lower than the third resonant frequency.

26. The antenna of claim 24 wherein the second resonant element is conductively connected to the ground region.

27. The antenna of claim 24 further comprising a signal terminal for supplying a signal to electronics components mounted on the substrate when the antenna is operative in a receiving mode.

28. The antenna of claim 27 wherein the first and the third resonant elements are conductively connected at the signal terminal.

29. The antenna of claim 24 wherein the second resonant element is conductively connected to the first resonant element proximate the signal terminal.

30. The antenna of claim 24 wherein the first resonant element comprises two concentric spaced-apart arcuate conductive elements conductively joined by a bridging element conductively connected between a first end of each of the arcuate conductive elements and forming an opening at a second end of each of the arcuate elements, and wherein a shape of the arcuate elements is responsive to a shape of the space envelope.

31. The antenna of claim 30 wherein the spaced-apart arcuate conductive elements define a gap therebetween, and wherein the third resonant element extends through the opening and is disposed within the gap and concentric with the arcuate conductive elements.