Coaxial continuous transverse stub element device antenna array and filter

• US 6,201,509 B1
• Filed: 11/05/1999
• Issued: 03/13/2001
• Est. Priority Date: 11/05/1999
• Status: Expired due to Term

• Current Assignee: University of Utah (State of Utah)
• Original Assignee: University of Utah Research Foundation (State of Utah)
• Inventors: Zhang, Zhijun, Yun, Zhengqing, Iskander, Magdy F.
• Primary Examiner(s): Wong, Don
• Assistant Examiner(s): NGUYEN, HOANG V
• Application Number:
  US09/434,886
• Time in Patent Office: 494 Days
• Field of Search: H01/Q 1.300, H01/Q.904, H01/Q.112, 343/785, 343/787, 343/790, 343/791, 343/792, 343/890
• US Class Current: 343/791
• CPC Class Codes: H01Q 21/10 Collinear arrangements of substantially straight elongated conductive units
• CPC Class Codes: H01Q 9/0407 Substantially flat resonant element parallel to ground plane, e.g. patch antenna dipole H01Q9/285; monopole H01Q9/40

Abstract

A continuous transverse stub element array structure which forms a coaxial geometry formed from a plurality of cylindrical segments, wherein each of the cylindrical segments has a rim at a top end and a bottom end, wherein each rim extends transversely away from the cylindrical segment relative to a longitudinal axis thereof to thereby form a stub element, wherein the individual cylindrical transverse stub elements are aligned end-to-end to thereby form a coaxial cable structure which surrounds a central core material. The series of these stubs form reactive or radiating elements for microwave, millimeter-wave, and quasi-optical filters and antennas. Purely reactive elements are formed by leaving the conductive coating on the terminus of the stub elements, whereas radiating elements are formed when stub elements of moderate radius are opened to free space. For tunability, each of the plurality of cylindrical segments and the central axis materials are coated with a conductive material which is ferro-electrical or liquid crystal in nature. The individual stub elements are separated from each other by air gaps or an appropriate material.

Claims

1. An antenna array structure formed from a plurality of continuous transverse stub elements in a coaxial relationship, said array structure comprising:

a plurality of cylindrical segments, wherein each of the plurality of cylindrical segments has a rim at a top end and at a bottom end, wherein each rim extends transversely away from the cylindrical segment relative to a longitudinal axis, wherein the plurality of cylindrical segments are longitudinally separated from each other, and wherein the plurality of cylindrical segments are comprised of at least a dielectric material;

a core element parallel to the longitudinal axis and around which the plurality of cylindrical segments are disposed to thereby form a coaxial relationship therewith;

wherein the plurality of cylindrical segments and the core element are coated with a thin and continuous conductive layer of material, and wherein a transverse stub element is formed from immediately adjacent cylindrical segments; and

a coupling end which is electrically coupled to a first cylindrical segment of the plurality of cylindrical segments, and to the core element, to thereby provide a feed for received and transmitted signals.

2. The array structure as defined in claim 1 wherein immediately adjacent rims of each transverse stub element are electrically isolated from each other to thereby form an open circuit, resulting in the transverse stub element functioning as a radiating element of an antenna.

3. The array structure as defined in claim 2 wherein immediately adjacent rims of each transverse stub element are electrically coupled to each other to thereby form a short circuit, resulting in the transverse stub element functioning as a non-radiating element of a filter and matching network designs.

4. The array structure as defined in claim 3 wherein the array structure further comprises a matched couplet formed from a radiating transverse stub element which is immediately adjacent to a non-radiating stub element, wherein a plurality of matched couplets are linked in series so as to form a coaxial relationship.

5. The array structure as defined in claim 4 wherein a diameter of the plurality of radiating elements is equal, wherein a diameter of the plurality of non-radiating elements is equal, and wherein the diameter of the plurality of radiating elements is not the same as the diameter of the plurality of non-radiating element.

6. The array structure as defined in claim 1 wherein the plurality of cylindrical segments are approximately equal in length along the longitudinal axis, and approximately equal in diameter.

7. The array structure as defined in claim 1 wherein the plurality of cylindrical segments are variable in length along the longitudinal axis, and variable in diameter.

8. The array structure as defined in claim 1 wherein each rim of the plurality of cylindrical segments are generally circular and approximately equal in diameter.

9. The array structure as defined in claim 1 wherein the rims which form the transverse stub element are characterized as not being identical.

10. The array structure as defined in claim 9 wherein the rims are formed by selecting structural features which are selected from the group of structural features including slope, diameter, continuity, separation from an immediately adjacent rim, thickness, inclination of radiation surface, cross section, distribution of the transverse stub elements, shape of the rim in a plane which is transverse to the longitudinal axis, and the addition of other structures to the rims.

11. The array structure as defined in claim 10 wherein the slope of the rim is selected from the group of slopes including tapering, step-wise segmented, and any combination thereof.

12. The array structure as defined in claim 10 wherein the shape of the rim in a plane which is transverse to the longitudinal axis is selected from the group of shapes including circular, oval, polygonal, and sectorial.

13. The array structure as defined in claim 1 wherein the core element is larger in circumference at predetermined locations to thereby modify impedance matching and radiation characteristics.

14. The array structure as defined in claim 1 wherein the core element further comprises at least two different but conductive materials which are in electrical contact with each other.

15. The array structure as defined in claim 1 wherein the core element further comprises a plurality of protuberances which extend transversely with respect to the longitudinal axis.

16. The array structure as defined in claim 1 wherein a gap between each of the plurality of cylindrical segments is open to air.

17. The array structure as defined in claim 16 wherein the material disposed in the gap between the plurality of cylindrical segments is selected from the group of materials including TEFLON™

, low density foam, rexolite, polyethylene, stycast, lexan and other materials of similar electrical properties which provide structural integrity to the array structure.

18. The array structure as defined in claim 16 wherein the material disposed in the gap between the plurality of cylindrical segments is comprised of a plurality of layers to thereby improve features including tunability, beam steering and losses.

19. The array structure as defined in claim 1 wherein a material is disposed in a gap between each of the plurality of cylindrical segments so as to fill the gap.

20. The array structure as defined in claim 1 wherein the thin and continuous conductive layer is comprised of a ferro-electric material.

21. The array structure as defined in claim 20 wherein the ferro-electric material is selected from Barium Strontium Titanium Oxide.

22. The array structure as defined in claim 1 wherein the thin and continuous conductive layer is comprised of a liquid crystal material.

23. The array structure as defined in claim 1 wherein the thin and continuous conductive layer of material is applied as a thin film of relatively uniform thickness.

24. The array structure as defined in claim 23 wherein the thin and continuous conductive layer of material is further comprised of a plurality of relatively thin and continuous conductive layers of material.

25. The array structure as defined in claim 1 wherein a thickness of the thin and continuous conductive layer of material is determined as a function of desired tuning capabilities and loss characteristics of the array structure.

26. The array structure as defined in claim 25 wherein the desired tuning capabilities are achieved as a function of applied biasing voltage to the thin and continuous conductive layer of material.

27. An array structure formed from a single and continuous transverse stub element which is formed around a center conductor in a coaxial arrangement, said array structure comprising:

at least two cylindrical segments, wherein the at least two cylindrical segments include at least two helical rims which extend transversely away from the at least two cylindrical segment relative to a longitudinal axis, wherein the at least two cylindrical segments are separated by a predetermined amount, wherein the at least two cylindrical segments are comprised of a dielectric material, and wherein the at least two cylindrical segments define a single array element;

a core element around which the at least two cylindrical segments are disposed to thereby form the coaxial relationship;

wherein the at least two cylindrical segments and the core element are coated with a thin and continuous conductive layer of material, and wherein the stub elements are formed from immediately adjacent rims of the at least two cylindrical segments; and

a coupling end which is electrically coupled to the at least two cylindrical segments and to the core element, to thereby provide a feed for received and transmitted signals.

28. A method for providing an omnidirectional array structure formed from a plurality of continuous transverse stub elements in a coaxial relationship, said method comprising the steps of:

(1) forming the plurality of continuous transverse stub elements, wherein a single transverse stub element is formed at a junction of two immediately adjacent but separate spool-shaped segments, wherein each of the plurality of continuous transverse stub elements is comprised of a dielectric material;

(2) forming a core element around which the plurality of continuous transverse stub elements are disposed to thereby form a coaxial relationship;

(3) coating the plurality of continuous transverse stub elements and the core element with a thin and continuous conductive layer of material; and

(4) providing a coupling end which is electrically coupled to a first transverse stub element and to the core element, to thereby provide a feed for receiving and transmitting signals.

29. The method as defined in claim 28 wherein the method further comprises the step of forming a radiating element of an antenna by electrically isolating immediately adjacent rims of each transverse stub element to thereby form an open circuit.

30. The method as defined in claim 29 wherein the method further comprises the step of forming non-radiating element by electrically coupling immediately adjacent rims of each transverse stub element to thereby form a filter and matching network designs.

31. The method as defined in claim 30 wherein the method further comprises the steps of:

(1) coupling a radiating element together with a non-radiating element to thereby form a stub element matched couplet; and

(2) linking in series a plurality of the stub element matched couplets.

32. The method as defined in claim 31 wherein the method further comprises suppressing coupler-radiator reflections through destructive interference of radiating and non-radiating stub element matched couplets.

33. The method as defined in claim 31 wherein the method further comprises scanning broadside by using the radiating and non-radiating stub element matched couplets.

34. The method as defined in claim 31 wherein the method further comprises the step of modifying bandwidth characteristics of the array structure by selectively modifying structural features of the continuous transverse stub elements.

35. The method as defined in claim 34 wherein the method further comprises the step of modifying at least one rim of the continuous transverse stub elements, wherein the modifications include altering a slope, diameter, continuity, separation from an immediately adjacent rim, thickness, inclination of radiation surface, cross section, distribution of the transverse stub elements, shape of the rim in a plane which is transverse to the longitudinal axis, and the addition of other structures to the rims.

36. The method as defined in claim 35 wherein the method further comprises the step of modifying a shape of the rim in a plane which is transverse to the longitudinal axis to thereby control an azimuth of a radiation pattern of each continuous transverse stub element.