Hermetically sealed waffle-wall configured assembly including sidewall and cover radiating elements and a base-sealed waveguide window

• US 5,218,373 A
• Filed: 10/01/1990
• Issued: 06/08/1993
• Est. Priority Date: 10/01/1990
• Status: Expired due to Term

• Current Assignee: Harris Corporation (L3Harris Technologies, Inc.)
• Original Assignee: Harris Corporation (L3Harris Technologies, Inc.)
• Inventors: Vought, Ronald, Heckaman, Douglas
• Primary Examiner(s): Hille, Rolf
• Assistant Examiner(s): BROWN, PETER T
• Application Number:
  US07/590,813
• Time in Patent Office: 981 Days
• Field of Search: 343/700 MS, 343/872, 343/873, 343/878, 343/879, 343/778, 343/786, 343/772, 343/782-785, 343/846, 343/847, 174/51, 174/52.3, 174/52.4, 361/392, 361/394-396, 361/399, 361/424, 333/246, 333/247, 343/778, 343/786, 343/772, 343/782-785, 343/846, 343/847
• US Class Current: 343/786
• CPC Class Codes: H01Q 1/405 Radome integrated radiating elements
• CPC Class Codes: H01Q 13/04 Biconical horns biconical dipoles comprising two conical surfaces having collinear axes and adjacent apices and fed by a two-conductor transmission line H01Q9/28
• CPC Class Codes: H01Q 15/006 Selective devices having photonic band gap materials or materials of which the material properties are frequency dependent, e.g. perforated substrates, high-impedance surfaces

Abstract

Directed millimeter wave radiation from internal elements of a microwave circuit through the housing cover, housing base, and side walls of a hermetically-sealed MMIC integrated subsystem assembly uses a waffle-wall array of conductive posts as a band rejection filter to provide walls which guide the radiated waves through a hermetically sealed window in the housing base for waveguide propagation or to a dielectric side wall or cover to radiate energy therethrough. For a waveguide launch, the launch probe is printed on a TEM mode microstrip transmission line substrate and is located over or on a dielectric window formed at the end of an air filled waveguide. A waveguide-like mode of propagation is launched perpendicular to the microstrip substrate and the energy is transmitted through the dielectric window into the air dielectric waveguide which extends through the housing base. Side wall mounted antennas use radiating elements placed near the side walls of the subsystem assembly and are surrounded on their remaining sides by the conductive post structure. The launched waves propagate toward the dielectric side wall to radiate outwardly from the subsystem assembly. For radiating energy through the subsystem assembly cover, a launch probe is located under a dielectric aperture in the hermetically-sealed cover.

Claims

1. An assembly for waveguide launching microwave transmissions, comprising:

a housing base having a first opening formed through said housing base;

a substrate formed atop said housing base and having a second opening extending therethrough, said first and second openings substantially overlapping;

a housing cover enclosing said substrate and forming a cavity between said substrate and said housing cover, wherein said housing base and housing cover are hermetically sealed at their edges;

a launch substrate having top and bottom surface arranged in said second opening in the plane of said substrate and having dimensions less than those of said second opening to form an air gap between said launch substrate and said substrate;

a waveguide having side walls extending at one end through said first opening, said sidewalls being hermetically sealed at their one end to said launch substrate'"'"'s bottom surface;

a first radiating element arranged on said top surface of said launch substrate for launching the microwave transmissions;

a periodic array of conductive posts arranged perpendicularly to the plane of said substrate and launch substrate; and

a microstrip ground plane arranged perpendicularly to said conductive posts, wherein said conductive posts extend between said housing cover and substrate to provide an RF ground connection from said microstrip ground plane to said housing cover.

2. An assembly according to claim 1, further comprising:

a microstrip transmission line fabricated on said substrate;

a ribbon bond coupled at one end to said microstrip transmission line and at its other end to said first radiating element, said ribbon bond being formed across said air gap.

3. An assembly according to claim 2, further including at least one other radiating element arranged orthogonally to the first radiating element on said launch substrate.

4. An assembly according to claim 2, wherein said launch substrate is a dielectric launch substrate.

5. An assembly according to claim 4, wherein said dielectric launch substrate is formed from a ceramic composition.

6. An assembly according to claim 4, wherein said dielectric launch substrate is formed from a glass composition.

7. An assembly according to claim 1, wherein said hermetic seal between said launch substrate'"'"'s bottom surface and the waveguide side walls is a solder seal.

8. An assembly according to claim 1, wherein said waveguide is circular.

9. An assembly according to claim 1, wherein said waveguide is rectangular.

10. An assembly according to claim 1, wherein said periodic array provides isolation and backshorting for said first radiating element.

11. An assembly for waveguide launching microwave transmissions, comprising:

a housing base including a first opening formed therethrough having inner side walls;

a substrate made of an organic material, having top and bottom surfaces, located atop said housing base;

a housing cover attached to said housing base and hermetically enclosing said substrate;

a first waveguide section, having a low thermal coefficient of expansion and an outer surface, inserted in said first opening in the housing base, said first waveguide section having one end spaced apart from said bottom surface of the substrate, said first waveguide section having a transformer section located at its other end away from said substrate;

a choke joint for coupling the first waveguide section to the housing base for absorbing differentials in thermal coefficients of expansion;

a radiating element aligned over said first waveguide section;

a two-dimensional array of conductive posts extending substantially perpendicularly to said top surface and said housing cover,

a microstrip ground plane arranged perpendicular to said conductive posts, wherein said conductive posts provide an RF ground from said microstrip ground plane to said housing cover, a number of said conductive posts surrounding said radiating element; and

wherein said choke joint comprises;

an eyelet having inner and outer surfaces and including a flange section, said inner surface of said eyelet compression sealed against the outer surface of said first waveguide section, said flange section being hermetically sealed to a lower end of said housing base; and

a first space formed between said outer surface of said eyelet and said inner side walls of the opening in the housing base.

12. An assembly according to claim 11, further comprising:

a second waveguide section larger than said first waveguide section and hermetically sealed at one open end to said flange section; and

wherein the transformer section of said first waveguide section extends into the open end of said second waveguide section for impedance matching between the first and second waveguide sections.

13. An assembly according to claim 12, wherein said first waveguide section is a quartz waveguide and said second waveguide section is an air dielectric waveguide.

14. An assembly for waveguide launching microwave transmissions, comprising:

a housing base including a first opening formed therethrough having inner side walls;

a substrate made of an organic material, having top and bottom surface, located atop said housing base;

a housing cover attached to said housing base and hermetically enclosing said substrate;

a first waveguide section, having a low thermal coefficient of expansion and an outer surface, inserted into said first opening in the housing base, said first waveguide section having one end spaced apart from said bottom surface of the substrate, said first waveguide section having a transformer section located at its other end away from said substrate;

a choke joint for coupling the first waveguide section to the housing base for absorbing differentials in thermal coefficients of expansion;

a radiating element aligned over said first waveguide section;

a two-dimensional array of conductive posts extending substantially perpendicularly to and between said top surface and said housing cover;

a microstrip ground plane arranged perpendicular to said conductive posts, wherein said conductive posts provide an RF ground from said microstrip ground plane to said housing cover, a number of said conductive posts surrounding said radiating element; and

a second opening formed in said substrate substantially overlapping said first opening in said housing base wherein the radiating element is printed on the one end of the first waveguide section extending through said first opening; and

a ribbon bond coupling said radiating element with the top surface of said substrate.

15. An assembly according to claim 14, wherein said choke joint comprises:

an eyelet having inner and outer surfaces and including a flange section, said inner surface of said eyelet compression sealed against the outer surface of said waveguide section, said flange section being hermetically sealed to a lower end of said housing base; and

a first space formed between said outer surface of said eyelet and said inner side walls of the opening in the housing base.

16. An assembly according to claim 15, further comprising:

a second waveguide section larger than said first waveguide section and hermetically sealed at one open end to said flange section; and

wherein the transformer section of said first waveguide section extends into the open end of said second waveguide section for impedance matching between the first and second waveguide sections.

17. An assembly according to claim 16, wherein said first waveguide section is a quartz waveguide and said second waveguide section is an air dielectric waveguide.

18. An assembly for waveguide launching microwave transmissions, comprising:

a housing base having a thermal coefficient of expansion;

an opening formed through said housing base having inner side walls;

a microstrip substrate, having top and bottom surfaces, located atop said housing base;

a housing cover attached to said housing base enclosing said microstrip substrate, said housing cover being hermetically sealed to the housing base;

a first waveguide section, having a thermal coefficient of expansion substantially similar to that of said housing base, said first waveguide section having one end extending into said opening in the housing base up to said bottom surface of the microstrip substrate and forming a transformer section at the other end away from said microstrip substrate;

a waveguide seal compression sealed on its inner surface to the outside of said first waveguide section and on its outer surface being soldered to said inner side walls of the housing base;

a radiating element located over said first waveguide section; and

a periodic array of conductive posts extending substantially perpendicular to and between said top surface and said housing cover,

a microstrip ground plane arranged perpendicular to said conductive posts, wherein said conductive posts provide an RF ground from said microstrip ground plane to said housing cover, a number of said conductive posts surrounding said radiating element; and

a second waveguide section larger than said first waveguide section and hermetically sealed at one open end to said waveguide seal and housing base; and

wherein the transformer section of said first waveguide section extends into the open end of said second waveguide section for impedance matching between the first and second waveguide sections.

19. An assembly according to claim 18, wherein said first waveguide section is a quartz waveguide and said second waveguide section is an air dielectric waveguide.

20. An assembly for waveguide launching microwave transmissions, comprising:

a housing base having a thermal coefficient of expansion;

an opening formed through said housing base having inner side walls;

a microstrip substrate, having top and bottom surfaces, located atop said housing base;

a housing cover attached to said housing base and enclosing said microstrip substrate, said housing cover being hermetically sealed to the housing base;

a first waveguide section, having a thermal coefficient of expansion substantially similar to that for said housing base, extending at one end into said opening in the housing base up to said bottom surface of the microstrip substrate and forming a transformer section at the other end;

wherein said first waveguide section is a ceramic waveguide having a metallized outer surface soldered directly to the inner side walls of said opening in the housing base;

a radiating element located over said first waveguide section; and

a periodic array of conductive posts arranged to extend substantially perpendicular to and between said top surface and said housing cover, a number of said posts surrounding said radiating element.

21. An assembly according to claim 20, further comprising:

a second waveguide section larger than said first waveguide section and hermetically sealed at one open end to said metallized outer surface and housing base;

wherein the transformer section of said first waveguide section extends into the open end of said second waveguide section for impedance matching between the first and second waveguide sections.

22. An assembly according to claim 21, wherein said second waveguide section is an air dielectric waveguide.

23. A structure for radiating waveguide mode transmissions from a ceramic side wall having top and bottom surfaces in an assembly, comprising:

a housing cover sealed at its edges to the top surface of the ceramic side wall;

a housing base sealed at its edges to the bottom surface of the ceramic side wall;

a substrate located atop of said housing base;

a plurality of conductive posts forming a periodic array, said plurality of posts each being arranged substantially perpendicular to and between said housing cover and substrate;

a radiating element extending upward from said substrate and unobstructively located near the ceramic side wall in front of one of said conductive posts; and

wherein a number of said conductive posts including said one conductive post reject waveguide mode transmissions not radiated toward the ceramic side wall.

24. A structure according to claim 23, wherein said ceramic side wall includes corners and wherein said radiating element is located near one of said corners of said ceramic side wall.

25. A structure according to claim 23, wherein the ceramic side wall includes a bulge portion extending outward from the assembly in the vicinity of said radiating element for impedance matching.

26. A structure according to claim 23, wherein said radiating element is spaced approximately 1/4 wavelength in front of said one conductive post.

27. A structure according to claim 23, further comprising:

an absorption film covering portions of the ceramic side wall exterior of the assembly away from said radiating element for attenuating spurious waveguide mode transmissions within the ceramic side wall.

28. A structure according to claim 23 wherein said radiating element is surrounded by a dielectric sleeve support bonded to said substrate.

29. A structure according to claim 23, further comprising:

a multi-sectional dielectric guide transformer extending along said substrate from said radiating element to the ceramic side wall.

30. A method for radiating microwave transmissions from a ceramic side wall, having an interior and an exterior, of a hermetically sealed assembly including a housing base, housing cover, microstrip ground plane, and substrate, said substrate being located on top of said housing base between said housing base and housing cover, the method comprising the steps of:

providing a periodic two-dimensional matrix of conductive posts extending between the housing cover and substrate to provide an RF connection between the microstrip ground plane and said housing cover; and

arranging a substantially vertical radiating element on the substrate, said radiating element being located between the ceramic side wall and one conductive post of said periodic two-dimensional matrix along a line perpendicular to the ceramic side wall running through the one conductive post, said one conductive post reflecting and directing microwave transmissions launched from the radiating element toward the ceramic side wall along said perpendicular line; and

forming an impedance matching bulge along said perpendicular line on the exterior of said ceramic side wall.

31. A structure for radiating microwave transmissions, comprising:

a dielectric housing cover having an inner metallization layer;

an aperture formed in said inner metallization layer;

a housing base hermetically sealed to the housing cover and forming a ground plane;

a substrate located atop said housing base;

a plurality of conductive posts arranged in a two-dimensional matrix array forming a ground current coupling between said inner metallization layer and said ground plane;

a dielectric puck inserted into an opening in said substrate and housing base between a number of the plurality of conductive posts forming said matrix and underneath said aperture in said inner metallization layer; and

a radiating element formed on said dielectric puck for launching microwave transmissions perpendicular to said substrate and through said aperture and dielectric housing cover.

32. A structure according to claim 31, wherein said aperture is formed by etching away a portion of said inner metallization layer.

33. A structure according to claim 32, further comprising a second dielectric puck arranged between said radiating element and said housing cover.

34. A structure for radiating microwave transmissions from an assembly, comprising:

a metal housing cover forming a top shield;

a housing base hermetically sealed to said housing cover forming a ground plane;

a substrate located atop said housing base;

a plurality of conductive posts arranged in a two dimensional matrix forming a ground current coupling between said top shield and said ground plane;

a dielectric puck inserted into an opening in said substrate and housing base between a number of said plurality of conductive posts forming said matrix of conductive posts;

an aperture formed in said housing cover over said dielectric puck;

a radiating element formed on said dielectric puck for launching microwave transmissions perpendicular to said substrate; and

a dielectric window formed in said aperture for allowing transmission of said launched microwave transmissions through said housing cover.

35. A structure according to claim 34, wherein said metal housing cover has a thermal coefficient of expansion different from that of said dielectric window and further comprising:

a choke joint for coupling the dielectric window to said metal housing cover to absorb the differential thermal coefficients of expansion.