Reconfigurable interleaved phased array antenna

• US 6,388,631 B1
• Filed: 03/19/2001
• Issued: 05/14/2002
• Est. Priority Date: 03/19/2001
• Status: Expired due to Term

• Current Assignee: Raytheon Company (Rtx Corporation), HRL Laboratories LLC (The Boeing Co.)
• Original Assignee: Raytheon Company (Rtx Corporation), HRL Laboratories LLC (The Boeing Co.)
• Inventors: Schaffner, James H., Livingston, Stan W., Lee, Jar J., Loo, Robert Y.
• Primary Examiner(s): Ho, Tan
• Application Number:
  US09/811,934
• Time in Patent Office: 421 Days
• Field of Search: 343/767, 343/770, 343/853, 343/771, 343/876, 343/872, 342/373, 342/374, 342/375
• US Class Current: 343/767
• CPC Class Codes: H01Q 13/10 Resonant slot antennas
• CPC Class Codes: H01Q 21/064 using horn or slot aerials slotted waveguides arrays H01Q21/005
• CPC Class Codes: H01Q 21/22 Antenna units of the array energised non-uniformly in amplitude or phase, e.g. tapered array or binomial array
• CPC Class Codes: H01Q 3/24 varying the orientation by switching energy from one active radiating element to another, e.g. for beam switching

Abstract

A reconfigurable wide band phased array antenna for generating multiple antenna beams for multiple transmit and receive functions. The antenna array comprises multiple long non-resonant TEM slot antenna apertures with RF MEMS switches disposed within the slots. The RF MEMS switches are positioned directly within the feed lines across the slots to directly control the coupling of RF energy to the slots. Multiple RF MEMS switches are used within each slot, which allows multiple transmit/receive functions and/or multiple frequencies to be supported by each slot. The frequency coverage provided by the slot antenna has a greater than 10:1 frequency range.

Claims

1. An array antenna for radiating RF energy comprising:

a plurality of non-resonant slot apertures, each non-resonant slot aperture having a first side and a second side and an opening between the first side and the second side;

a plurality of antenna feeds, one or more antenna feeds of the plurality of antenna feeds located on the first side or the second side of each non-resonant slot aperture;

a plurality of switches deployed immediately adjacent to the each one of the plurality of non-resonant slot apertures, each switch of the plurality of switches connected to at least one antenna feed and controllable to selectively couple RF energy from at least one antenna feed located on one side of an adjacent slot aperture across the opening of the adjacent non-resonant slot aperture to the other side of the adjacent non-resonant slot aperture.

2. An array antenna according to claim 1, wherein the plurality of switches comprises a plurality of RF MEMS switches.

3. An array antenna according to claim 2, the array antenna having a shortest operating wavelength and a longest operating wavelength and wherein the plurality of non-resonant slot apertures comprises:

a metal layer having an upper side and a lower side and having one or more slots, each slot comprising an opening in the metal layer having a length longer than the longest operating wavelength and a width less than the shortest operating wavelength; and

a substrate layer having a top side and a bottom side, the substrate layer comprising substrate material disposed on the upper side of the metal layer, wherein the bottom side of the substrate layer is adjacent the metal layer and the antenna feeds are positioned on the top side of the substrate layer; and

one or more vias projecting from the top side of the substrate layer to the bottom side of the substrate layer and in electrical contact with the metal layer.

4. An array antenna according to claim 3 wherein the plurality of RF MEMS switches are disposed on the substrate layer, the RF MEMS switches being positioned above the openings in the metal layer and controllable to selectively electrically connect or disconnect at least one antenna feed located on one side of the corresponding slot aperture to at least one via of the one or more vias.

5. An array antenna according to claim 3 wherein the substrate layer has a plurality of slots, each slot in the plurality of slots being positioned adjacent to and generally above the openings in the metal layer and having a length and width generally equal to the openings in the metal layer and the plurality of RF MEMS switches being disposed at or directly above the openings in the metal layer, the RF MEMS switches being controllable to selectively electrically connect or disconnect at least one antenna feed located on one side of the corresponding slot aperture to at least one via of the one or more vias.

6. An array antenna according to claim 3 further comprising a radome disposed on the lower side of the metal layer.

7. An array antenna according to claim 6 wherein the radome comprises a plurality of dielectric layers, the dielectric layers each having a dielectric constant and a width, the dielectric constant and width of each layer varying from the layer adjacent to the metal layer to a layer adjacent free space to match an impedance of the nonresonant slot apertures to an impedance of free space.

8. An array antenna according to claim 6 further comprising an absorber disposed above the top side of the substrate layer.

9. An array antenna according to claim 8 wherein the absorber comprises a metalized back plate.

10. An array antenna according to claim 2, wherein each RF MEMS switch in the plurality of RF MEMS switches comprises a cantilevered single pole single throw RF MEMS switch.

11. An array antenna according to claim 1, wherein the non-resonant slot apertures are disposed in a planar array and each non-resonant slot aperture has a longitudinal orientation, the longitudinal orientation of each slot aperture being generally parallel to the longitudinal orientation of every other slot aperture.

12. A phased array antenna according to claim 1, wherein the switches in the plurality of switches being selectively controllable to form antenna beams with different shapes.

13. A method of radiating and receiving RF energy with an antenna array having a shortest operating wavelength and a longest operating wavelength, the method comprising the steps of:

providing a plurality of non-resonant slot apertures;

providing a plurality of switches, one or more of said switches being disposed in proximity to each non-resonant slot aperture, each of said switches having a first position coupling RF energy to the aperture in proximity to the switch and having a second position isolating RF energy from the aperture in proximity to the switch;

switching a portion of the plurality of switches to the first position;

switching the remaining switches to the second position;

applying RF energy to the switches.

14. The method according to claim 13, wherein said switches are RF MEMS switches.

15. The method according to claim 14, wherein the plurality of non-resonant slot apertures comprise openings in a metal layer, the metal layer having an upper side and a lower side, and each opening having a length longer than the longest operating wavelength and a width less than the shortest operating wavelength.

16. The method according to claim 15 wherein a substrate layer is disposed on the upper side of the metal layer, the substrate layer having a top side and a bottom side, the bottom side of the substrate layer is disposed adjacent the upper side of the metal layer and the substrate layer has a plurality of electrically-conductive vias projecting from the top side of the substrate layer to the bottom side of the substrate layer, the electrically-conductive vias being in electrical contact with the metal layer.

17. The method according to claim 16 wherein the plurality of RF MEMS switches are disposed on the substrate layer, the RF MEMS switches being positioned above the openings in the metal layer and controllable to selectively couple RF energy to or isolate RF energy from the vias.

18. The method according to claim 16 wherein the substrate layer has a plurality of slots, each slot in the plurality of slots positioned generally above the openings in the metal layer and the plurality of RF MEMS switches are disposed above the openings in the metal layer, the RF MEMS switches controllable to selectively couple RF energy to or isolate RF energy from the vias.

19. The method according to claim 16 wherein the non-resonant slot apertures have an impedance and the metal layer has a radome disposed on the lower side of the metal layer, the radome comprising multiple dielectric layers, the width and dielectric constants of each dielectric layer of the multiple dielectric layers chosen to match the impedance of the non-resonant slot apertures to free space.

20. The method according to claim 16 wherein an absorber is disposed above the top side of the substrate layer, the absorber comprising a metalized back plate.

21. A beam-steered antenna array comprising:

a plurality of non-resonant slot apertures, each non-resonant slot aperture having a first side and a second side and an opening between the first side and the second side;

a plurality of groups of switches, each group of switches comprising a plurality of switches deployed immediately adjacent to the slot apertures, the switches controllable to selectively couple RF energy at different points across the opening of each non-resonant slot aperture;

a plurality of beamformers, each beamformer connected to a separate group of switches in the plurality of groups of switches; and

an RF switch selectively controllable to couple RF energy to a selected one of beamformers in the plurality of beamformers.

22. A beam-steered antenna array according to claim 21 wherein said non-resonant slot apertures are arranged as a planar array.

23. A beam-steered antenna array according to claim 21 wherein each switch in said plurality of switches is an RF MEMS switch, the RF MEMS switches being deployed at different points immediately above the openings in the non-resonant slot apertures.

24. A beam-steered antenna array according to claim 21 wherein the switches are controlled to form antenna beams with selectable shapes.

25. A beam-steered antenna array according to claim 21 wherein the antenna array has a shortest operating wavelength and each switch in each group of switches is disposed within one-tenth of the shortest operating wavelength of a switch from each of the other groups of switches.

26. A method of antenna beamforming , comprising the steps of:

providing a plurality of non-resonant slot apertures in an antenna array;

providing a plurality of groups of switches, each group of switches comprising a plurality of switches deployed at different positions immediately adjacent the non-resonant slot apertures, each of said switches having a first position coupling RF energy to the aperture in proximity to the switch and having a second position isolating RF energy from the aperture in proximity to the switch;

providing a plurality of beamformers, each beamformer connected to a separate group of switches in the plurality of groups of switches;

coupling RF energy to a selected one of the beamformers in the group of beamformers;

switching the switches in the group of switches connected to the selected beamformer to either the first position or the second position; and

switching the remaining switches to the second position.

27. The method of antenna beamforming according to claim 26 wherein the antenna array has a shortest operating wavelength and each switch in each group of switches is disposed within one-tenth of the shortest operating wavelength of a switch from each of the other groups of switches.

28. The method of antenna beamforming according to claim 26 wherein the switches are controlled to form antenna beams with selectable shapes.

29. A phased array antenna system having a shortest operating wavelength and a longest operating wavelength, the phased array system supporting multiple transmit/receive functions, the phased array antenna system comprising:

a plurality of transmit/receive modules, each transmit/receive module coupled to RF hardware providing one or more of the multiple transmit/receive functions, each transmit/receive module having one or more channels, each channel being coupled out of the transmit/receive module at one or more transmit/receive ports;

one or more non-resonant slot apertures, each slot aperture having a first side and a second side and an opening between the first side and the second side;

a plurality of antenna feeds, one or more antenna feeds of the plurality of antenna feeds located on a first side or a second side of a corresponding one of the slot apertures, each antenna feed coupled to one transmit/receive port of the one or more transmit/receive ports on one transmit/receive module of the plurality of transmit/receive modules; and

a plurality of switches disposed immediately adjacent to the non-resonant slot apertures, each switch of the plurality of switches connected to one antenna feed and controllable to selectively couple RF energy from the antenna feed located on one side of the corresponding slot aperture across the opening of the corresponding non-resonant slot aperture to the other side of the corresponding slot aperture.

30. The phased array antenna system according to claim 29 wherein each transmit/receive port of each transmit/receive module is coupled to one or more antenna feeds and at least one of the switches deployed immediately adjacent one non-resonant slot aperture and connected to one transmit/receive port of each transmit/receive module is disposed within a distance of one-tenth of the shortest operating wavelength to at least one of the switches connected to each other transmit/receive port of the transmit/receive module and deployed immediately adjacent the same non-resonant slot aperture.

31. A phased array antenna system according to claim 30, wherein the plurality of switches comprises a plurality of RF MEMS switches and wherein the one or more non-resonant slot apertures comprises:

a metal layer having an upper side and a lower side and having one or more slots, each slot comprising an opening in the metal layer having a length longer than the longest operating wavelength and a width less than the shortest operating wavelength; and

a substrate layer having a top side and a bottom side, the substrate layer comprising substrate material disposed on the upper side of the metal layer, wherein the bottom side of the substrate layer is adjacent the metal layer and the antenna feeds are positioned on the top side of the substrate layer; and

one or more vias projecting from the top side of the substrate layer to the bottom side of the substrate layer and in electrical contact with the metal layer.

32. A phased array antenna system according to claim 31 wherein the plurality of RF MEMS switches are disposed on the substrate layer, the RF MEMS switches being positioned above the openings in the metal layer and controllable to selectively electrically connect or disconnect at least one antenna feed located on one side of the corresponding non-resonant slot aperture to at least one via of the one or more vias.

33. A phased array antenna system according to claim 31 wherein the substrate has a plurality of slots, each slot in the plurality of slots positioned generally above the openings in the metal layer and the plurality of RF MEMS switches are disposed above the openings in the metal layer, the RF MEMS switches controllable to selectively electrically connect or disconnect at least one antenna feed located on one side of the corresponding slot aperture to at least one via of the one or more vias.

34. A phased array antenna system according to claim 29, wherein the plurality of switches comprises a plurality of RF MEMS switches.

35. A phased array antenna system according to claim 29 further comprising a radome having a plurality of dielectric layers, the dielectric layers each having a dielectric constant and a width, the dielectric constant and width of each layer chosen to provide impedance matching between the non-resonant slot apertures and free space.

36. A phased array antenna according to claim 29, wherein the non-resonant slot apertures are disposed in a planar array and each non-resonant slot aperture has a longitudinal orientation, the longitudinal orientation of each slot aperture being generally parallel to the longitudinal orientation of every other slot aperture.