Flat panel-configured electronically steerable phased array antenna having spatially distributed array of fanned dipole sub-arrays controlled by triode-configured field emission control devices

• US 5,835,062 A
• Filed: 11/01/1996
• Issued: 11/10/1998
• Est. Priority Date: 11/01/1996
• Status: Expired due to Term

• Current Assignee: Benhov GmbH, LLC (Intellectual Ventures LLC)
• Original Assignee: Harris Corporation (L3Harris Technologies, Inc.)
• Inventors: Kanaly, David B., Heckaman, Douglas E.
• Primary Examiner(s): Le, Hoanganh T.
• Application Number:
  US08/742,474
• Time in Patent Office: 739 Days
• Field of Search: 343/700 MS, 343/701, 343/840, 343/872, 343/786, 343/909, 343/753
• US Class Current: 343/700.0MS
• CPC Class Codes: H01Q 1/26 with electric discharge tube
• CPC Class Codes: H01Q 3/46 Active lenses or reflecting arrays
• CPC Class Codes: H01Q 9/065 Microstrip dipole antennas patch antenna H01Q9/0407

Abstract

A flat panel-configured electronically steered phased array antenna includes a planar distribution of densely nested microstrip dipole sub-arrays, arranged and controlled in a manner similar to microstrip `reflect-array` antenna elements. The resultant phase of a circularly polarized wave for a reflect-array fan-out distribution of dipole antenna elements is controlled by an associated plurality of triode-configured field emission devices. Each dipole element sub-array is plated to a resistive sub-layer on an interior surface of a flat first millimeter wave transmissive panel member of an evacuated flat panel type support structure. Mounted to a similar resistive layer on the interior surface of a second, flat panel member is a microstrip conductive layer partially overlapped around its periphery by respective fan-configured microstrip dipole antenna elements plated on the first panel member. Arranged between overlapping regions and overlapping portions of the respective dipole antenna elements are a plurality of elements, that form cathode and control gates of plural triode-configured field emission devices, the anodes of which are dipoles formed on the first plate member. These elements select a desired dipole pair within each subarray and control the current therein.

Claims

1. A phased array antenna comprising a plurality of spatially distributed radiation elements and an arrangement of field emission devices electrically coupled with said plurality of spatially distributed radiation elements, a respective one of said field emission devices having a first electrode coupled in circuit with one of said radiation elements, a second electrode coupled in circuit with a second electrode of another of said field emission devices, said another of said field emission devices having a first electrode thereof coupled in circuit with another of said radiation elements, and wherein each of said one and another of said field emission devices has a selectively controllable current flow path therethrough between first and second electrodes thereof, so as to control electrical coupling therethrough between said one and said another of said radiation elements.

2. A phased array antenna according to claim 1, wherein selected field emission devices are electrically coupled with selected sets of said radiation elements.

3. A phased array antenna according to claim 2, wherein selected field emission devices are electrically coupled with selected pairs of said radiation elements.

4. A phased array antenna according to claim 3, wherein said plurality of spatially distributed radiation elements comprises spatially distributed sets of radiation elements, each set of radiation elements comprising a sub-array of radiation elements spatially distributed in a regular geometric pattern.

5. A phased array antenna according to claim 4, wherein radiation elements of a respective sub-array comprise dipole elements spatially distributed in a regular geometric pattern about a center conductor element, and wherein respective pairs of arrays of said field emission devices are distributed in a diametrically opposed manner around the perimeter of said center conductor element, so as to provide an electrically controlled conductive path between respective pairs of said dipole elements.

6. A phased array antenna according to claim 5, further including an evacuated hermetically sealed structure within which said plurality of spatially distributed radiation elements and said arrangement of field emission devices are supported, and wherein said hermetically sealed structure comprises a first generally flat panel member that is generally transparent to electromagnetic waves having a half-wavelength corresponding to an overall effective electrical length of an electrically connected pair of said dipole elements, and a second generally flat panel member spaced apart from and hermetically sealed with said first generally flat panel member.

7. A phased array antenna according to claim 6, wherein said radiation elements are supported upon an interior surface of said first generally flat panel member, and wherein said arrangement of field emission devices is supported upon an interior surface of said second generally flat panel member.

8. A phased array antenna according to claim 7, wherein said second generally flat panel member is generally transparent to electromagnetic waves having said wavelength.

9. A phased array antenna according to claim 7, wherein said second generally flat panel member has a thickness corresponding to an integral number times one-quarter of said wavelength.

10. A phased array antenna according to claim 1, further including a hermetically sealed structure within which said plurality of spatially distributed radiation elements and said arrangement of field emission devices are supported.

11. A phased array antenna according to claim 10, wherein said hermetically sealed structure comprises a first generally flat panel member that is generally transparent to electromagnetic waves having a wavelength associated with a resonance frequency of said radiation elements, and a second generally flat panel member spaced apart from and hermetically sealed with said first generally flat panel member.

12. A phased array antenna according to claim 10, further comprising a radiating horn element attached with said hermetically sealed structure.

13. A phased array antenna according to claim 10, further comprising antenna pattern control circuitry coupled to said plurality of spatially distributed radiation elements.

14. A phased array antenna according to claim 1, wherein each of said field emission devices comprises a field emission triode device having a control electrode coupled to receive a control input for controlling current flow between first and second electrodes of said each field emission device.

15. A phased array antenna comprising a flat panel structure including first and second plate members that are effectively transparent to radiation in a frequency band of operation of said phased array antenna, said first and second plate members being spaced apart from and hermetically sealed with one another, so as to form a thin evacuated space between interior faces of said first and second plate members, a dipole array formed on the interior face of said first plate member, said dipole array being comprised of a generally planar distribution of microstrip dipole sub-arrays, each dipole sub-array comprising a plurality of microstrip dipole antenna elements spaced apart from one another and extending radially outwardly from a sub-array feed location, so as to form spaced apart pairs of diametrically opposed dipole elements within a respective sub-array, a microstrip conductive layer formed on the interior face of said second plate member so as to be partially overlapped, in projection, around its periphery by respective ones of said dipole antenna elements formed on said first plate member, and a plurality of elements, that form respective cathode and control gates of a plurality of triode-configured field emission devices, the anodes of which correspond to dipole elements formed on the interior face of said first plate member, said devices being disposed upon said microstrip conductive layer on the interior face of said second plate member.

16. A phased array antenna according to claim 15, wherein a respective triode-configured field emission device comprises a conically shaped electron-emitting cathode element mounted to said microstrip conductive layer on said interior face of said second panel member, and a gate electrode having an iris adjacent to and concentric with an apex portion of said conically shaped electron-emitting cathode element and operative to control an electron beam emitted by said cathode element and collected by an associated anode dipole element, thereby controlling a current flow path between a diametrically opposed pair of dipole elements and said microstrip conductive layer.

17. A phased array antenna according to claim 15, wherein said first plate member comprises a low millimeter wave loss dielectric material, having a thickness corresponding to an integral number of one-half the wavelength of a sub-array dipole resonance frequency, so as to be effectively transparent to incoming electromagnetic waves in a millimeter band of operation of said antenna.

18. A phased array antenna according to claim 15, wherein an exterior surface of said first plate member is coated with one or more auxiliary transformer layers.

19. A phased array antenna according to claim 15, wherein said second plate member has a thickness corresponding to an integral number N times one-quarter the wavelength of a sub-array dipole resonance frequency, so that said second plate member is operative as a half-wavelength reflector of waves incident upon an exterior surface of the first plate and travelling therethrough to be incident upon said second plate member.

20. A phased array antenna according to claim 15, wherein an exterior surface of said second plate is coated with a thin metal layer, which functions electrically as a ground plane.

21. A phased array antenna according to claim 15, wherein said second plate member has a thickness corresponding to an integral number N times one-half the wavelength of a sub-array dipole resonance frequency, so that said second plate member is operative as a half-wavelength transmitter of waves incident upon an exterior surface thereof and travelling therethrough to be incident upon said first plate member.

22. A phased array antenna according to claim 15, wherein an exterior surface of said second plate member is coated with one or more auxiliary transformer layers.

23. A phased array antenna according to claim 15, further including a first thin resistive film formed on the interior face of said first plate member and being connected to a DC power supply of a first polarity, so as to provide a current source sub-layer for said field emission devices, anodes for which correspond to radial dipole elements of said sub-arrays mounted upon said first thin resistive film.

24. A phased array antenna according to claim 23, further including a second thin resistive film formed on the interior face of said second plate member and being connected to a DC power supply of a second polarity, so as to provide a current sink sub-layer for said field emission devices, cathodes for which correspond to said microstrip conductor mounted a peripheral portion of said second thin resistive film.

25. A phased array antenna according to claim 24, wherein a respective triode-configured field emission device comprises a conically shaped electron-emitting cathode element mounted to said microstrip conductive layer on said second thin resistive layer formed on said interior face of said second plate member, and a gate electrode having an iris adjacent to and concentric with an apex portion of said conically shaped electron-emitting cathode element and operative to control an electron beam emitted by said cathode element and collected by an associated anode dipole element on said first thin resistive layer on said first plate member, thereby controlling a current flow path between a diametrically opposed pair of dipole elements and said microstrip conductive layer, said gate electrode being formed on a dielectric layer adjacent to an apex portion of a cathode element, and a resistive trace coupling said gate electrode to an external control circuit at a peripheral region of said flat panel structure. The resistive traces have sufficiently low electrical resistance to allow DC current to be supplied to a turned-on triode-configured field emission device, but sufficiently high to provide low attenuation to millimeter waves incident upon the antenna, and wherein the voltage on the control grid traces controls the electron beam emitted by the cathode elements and collected by the anode dipole elements, thereby controlling the current flow path between diametrically opposed pair of dipole elements and the cathode conductor and which of the diametrically opposed anode dipole pairs of the sub-arrays are selected.

26. A phased array antenna according to claim 15, wherein said flat panel structure is affixed to a mounting ring structure backed by a rear cover panel, and further including a section of waveguide which extends from a waveguide feed horn supported adjacent to an exterior face of said first plate member to a transceiver module, that is mounted to a second end of said section of waveguide supported adjacent to an exterior face of said second plate member, such that the transceiver module is positioned directly adjacent to said rear cover panel, and further including beam pattern control circuits mounted around the periphery of said flat panel structure, and wherein said control gates of said plurality of triode-configured field emission devices are coupled to said beam pattern control circuits.

27. A phased array antenna according to claim 15, wherein said flat panel structure is affixed to a front surface portion of a mounting ring structure, and further including a feed horn mounted to a rear surface of said mounting ring structure, so that said feed horn faces an exterior face of said second plate member, and is arranged to be coupled to a transceiver module supported adjacent thereto, and further including beam pattern control circuits mounted around the periphery of said flat panel structure, and wherein said control gates of said plurality of triode-configured field emission devices are coupled to said beam pattern control circuits.

28. A method of electronically steering an antenna pattern comprising the steps of:

(a) providing a phased array antenna of a plurality of spatially distributed radiation reflector elements;

(b) coupling a radiating horn element to said plurality of spatially distributed reflector radiation elements; and

(c) controlling the operation of selected ones of said plurality of spatially distributed radiation reflector elements by controlling conductivity through field emission devices and thereby defining and steering an antenna pattern associated with said plurality of spatially distributed radiation reflector elements, a respective one of said field emission devices having a first electrode coupled in circuit with one of said radiation reflector elements, a second electrode coupled in circuit with a second electrode of another of said field emission devices, said another of said field emission devices having a first electrode thereof coupled in circuit with another of said radiation reflector elements, and wherein each of said one and another of said field emission devices has a selectively controllable current flow path between first and second electrodes thereof, so as to control electrical coupling therethrough between said one and said another of said radiation reflector elements.

29. A method according to claim 28, wherein radiation reflector elements of a respective sub-array of said plurality of spatially distributed radiation reflector elements provided in step (a) comprise dipole elements spatially distributed in a regular geometric pattern about a center conductor element, respective pairs of arrays of said field emission devices are distributed in a diametrically opposed manner around the perimeter of said center conductor element, so as to provide an electrically controlled conductive path between respective pairs of said dipole elements.

30. A method according to claim 28, wherein each of said field emission devices comprises a field emission triode device having a control electrode coupled to receive a control input for controlling current flow between first and second electrodes thereof and step (c) comprises controlling current flow through said field emission triode devices, and thereby controlling the operation of selected ones of said plurality of spatially distributed radiation reflector elements.

31. A method according to claim 30, wherein said dipole elements and said field emission triode devices are housed in an evacuated hermetically sealed structure including generally flat plate members generally transparent to electromagnetic waves at the operating band of said antenna.

32. A method according to claim 31, wherein said dipole elements are supported upon an interior surface of a first generally flat plate member, and wherein said field emission, triode devices are supported upon an interior surface of a second generally flat plate member.

33. A phased array antenna comprising a plurality of spatially distributed radiation elements and an arrangement of triode-configured field emission devices electrically coupled with said plurality of spatially distributed radiation elements, and wherein selected arrays of said triode-configured field emission devices are electrically coupled with selected sets of said radiation elements.

34. A phased array antenna according to claim 33, wherein selected arrays of said triode-configured field emission devices are electrically coupled with selected pairs of said radiation elements.

35. A phased array antenna according to claim 34, wherein said plurality of spatially distributed radiation elements comprises spatially distributed sets of radiation elements, each set of radiation elements comprising a sub-array of radiation elements spatially distributed in a regular geometric pattern.

36. A phased array antenna according to claim 35, wherein radiation elements of a respective sub-array comprise dipole elements spatially distributed in a regular geometric pattern about a center conductor element, and wherein respective pairs of arrays of said field emission devices are distributed in a diametrically opposed manner around the perimeter of said center conductor element, so as to provide an electrically controlled conductive path between respective pairs of said dipole elements.