MICROWAVE OSCILLATOR WITH MULTIPLE GUNN DIODES IN A CAVITY RESONATOR

• US 3,737,802 A
• Filed: 11/12/1971
• Issued: 06/05/1973
• Est. Priority Date: 11/12/1971
• Status: Expired due to Term

• Current Assignee: Kenneth Nobuo Kawakami
• Original Assignee: Kenneth Nobuo Kawakami
• Inventors: Kawakami, Kenneth Nobuo
• Primary Examiner(s): Lake, Roy
• Assistant Examiner(s): Grimm, Siegfried H.
• Application Number:
  US05/198,287
• Time in Patent Office: 571 Days
• Field of Search: 331/55,56,96,97,17R,17G,17T
• US Class Current: 331/96
• CPC Class Codes: H03B 9/143 using more than one solid state device

Abstract

A solid state oscillator of a novel and inexpensive construction incorporates a plurality of microwave energy generating diodes, suitably Gunn diodes, for providing output powers in excess of that obtainable from a single diode. More particularly, the oscillator includes a rectangular waveguide type transmission line with a short circuit termination at one end. One or more pairs of diodes are located within the hollow of the waveguide; each diode of a given pair is geometrically arranged to be coupled between opposite ends of a cylindrical metal post and a respective top wall and bottom wall of the waveguide. A bias source is applied to the diodes by connection through a side wall to the metal post and to the waveguide. Microwave energy output coupling means, such as a waveguide, is connected to the open end of the waveguide.

Claims

1. A solid state oscillator comprising:

means forming a hollow rectangular waveguide passage, said waveguide passage being bordered by opposed top and bottom walls and opposed right and left side walls, said walls being of electrically conductive material and electrically in common;

a terminating back wall for terminating said waveguide passage to microwave energy;

first and second Gunn diodes located in said passage spaced from said back wall, each of said Gunn diodes containing a first terminal of a first polarity and a second terminal of a second polarity;

a post of electrically conductive material located in said passage spaced from said walls, said post having a predetermined height between its first and second ends less than the distance between said top and bottom walls of said waveguide passage and a maximum thickness dimension no more than one-quarter of the distance between said right and left side walls;

said first Gunn diode positioned at said first end of said post having its first terminal electrically in common with said first end of said post and having its second terminal electrically in common with said top waLl of said waveguide passage;

said second Gunn diode positioned at said second end of said post and having its first terminal electrically in common with said second end of said post and having its second terminal electrically in common with said bottom wall of said waveguide passage;

whereby said corresponding first terminals of each diode are electrically in common and said corresponding second terminals of each diode are electrically in common;

said first diode, said second diode, and said post being aligned substantially along a common axis to form a mechanical series arrangement, said common axis oriented substantially parallel to said side walls and perpendicular to said top and bottom walls and located at a predetermined position along the length of said waveguide passage spaced from said terminating back wall;

a third and fourth Gunn diode located in said passage spaced from said back wall, each of said third and fourth Gunn diode having a first terminal of a first polarity and a second terminal of a second polarity;

a second post of electrically conductive material spaced from said first post, said second post having a predetermined height between its first and second ends less than the distance between said top and bottom walls and a maximum thickness no more than one-quarter the distance between said right and left side walls;

said third Gunn diode positioned at said first end of said second post having its first terminal electrically in common with said first end of said second post and having its second polarity terminal electrically in common with said top wall of said waveguide passage;

said fourth Gunn diode positioned at the second end of said second post and having its first terminal electrically in common with said second end of said second post and having its second terminal electrically in common with said bottom wall of said waveguide passage;

said third and fourth Gunn diodes and said second post being aligned substantially along a common axis to form a mechanical series arrangement, said common axis oriented substantially parallel to said side walls and perpendicular to said top and bottom walls and located at the same predetermined position along the length of said passage as said common axis of said first mechanical series arrangement;

microwave energy coupling means connected to an end of said waveguide passage spaced from said diodes and remote from said back wall for coupling microwave energy to a load;

a source of bias voltage for said diodes, said bias source having a first output terminal of a first polarity and a second output terminal of a second polarity;

first electrically conductive means connecting said second output terminal of said source electrically in common with said waveguide walls, and second electrical conductor means connecting said first output terminal to said post; and

third electrical conductor means connecting said second post electrically in common with said first output terminal of said bias source;

whereby all four diodes generate microwave frequency energy of the same frequency and phase.

2. The invention as defined in claim 1 further comprising means for selectively positioning said back wall for changing the length of said passage.

3. The invention as defined in claim 2 further comprising a first minute opening in a side wall adjacent said first post and a second minute opening in a side wall adjacent said second post, said openings located in substantially a common plane with said common axes of said mechanical series arrangements and approximately midway between said top and bottom walls;

and wherein said second electrical conductor means includes a substantially straight portion which extends between said first opening and said first post and wherein said third electrical conductor means includes a straight portion which extends between said second opening and said second post;

whereby coupling of microwave energy from said passage to said bias supply is minimized.

4. The invention as defined in claim 1 further comprising first and second electrically conductive screw means, said first screw means coupled to said top wall and at an end abutting said second terminal of said first Gunn diode, and said second screw means coupled to said bottom wall and an end abutting said second terminal of said second Gunn diode, for placing said first terminals electrically in common with said walls and compressively supporting said mechanical series arrangement between said top and bottom walls.

5. The invention as defined in claim 2 further comprising two pairs of screws of electrically conductive material, each pair comprising a first screw coupled through a top wall and a second screw coupled through a bottom wall with the ends of said first and second screws abutting respectively second terminals of said diodes of a mechanical series arrangement to place said second terminals electrically in common and compressively maintain such mechanical series arrangement between said top and bottom walls.

6. A solid state microwave oscillator for generating microwave energy, said oscillator comprising:

a hollow metal waveguide having inner walls of electrically conductive material which border and define a passage of a predetermined height and width;

a terminating metal wall for closing said passage;

first and second microwave energy generating diodes located in said passage, each of said diodes containing a positive polarity terminal and a negative polarity terminal;

a post of electrically conductive material located in said passage and spaced from said inner walls;

said first diode positioned at a first end of said post and having its positive polarity terminal electrically in common with said post;

said second diode positioned at a second end of said post and having its positive polarity terminal electrically in common with said post;

said diodes and post thereby forming an elongated mechanical series structure;

said mechanical series structure being positioned at a predetermined position within and along the length of said passage spaced from said terminating metal wall; and

said negative polarity terminal of each respective one of said diodes being placed electrically in contact with a respective corresponding one of two opposed inner wall portions of said inner walls bordering said passage to support said structure therebetween and place said negative polarity diode terminals electrically in common through said inner walls;

third and fourth microwave energy generating diodes located in said passage, each of said diodes containing a positive polarity terminal and a negative polarity terminal;

a second post of electrically conductive material located in said passage and spaced from said inner walls and from said first post;

said third diode positioned at a first end of said second post and having its positive polarity terminal electrically in common with said second post and said fourth diode positioned at a second end of said second post and having its positive polarity terminal electrically in common with said second post to form a second elongated mechanical series structure;

said second mechanical series structure being positioned at the same predetermined position along the length of said waveguide passage as said first mechanical series structure and spaced from said first mechanical series structure along the width of said passage and oriented parallel to said first mechanical series structure; and

said negative polarity terminal of each respective one of said third and fourth diodes being placed electrically in contact with a respective corresponding one of two additional opposed inner wall portions of said inner walls bordering said passage to support said second mechanical series structure therebetween and to place said negative polarity diode terminals electrically in common through said inner walls;

microwave energy output means located at an enD of said passage remote from said terminating metal wall for coupling microwave energy to a load;

bias source means for said diodes, said bias source means having a positive polarity terminal and a negative polarity terminal;

first electrical conductor means for connecting said negative polarity terminal of said source in circuit with said waveguide walls;

second electrical conductor means for connecting said positive polarity terminal of said source to said post; and

third electrical conductor means for connecting said second post electrically in common with said first post, whereby each of said microwave energy generating diodes provides microwave frequency energy of the same frequency and in phase.

7. The invention as defined in claim 6 further comprising means for adjusting the position of said terminating metal wall along the length of said waveguide whereby the length of said passage may be varied.

8. The invention as defined in claim 6 wherein said microwave energy generating diodes comprise Gunn diodes.

9. The invention as defined in claim 6 further comprising an elongated dielectric member of dielectric material located between said diodes and said terminating metal wall and extending into said waveguide passage, and means to change the depth of extension of said member into said waveguide passage, whereby the oscillator frequency may be changed.

10. The invention as defined in claim 6 wherein said micro-wave energy output means comprises an open end of said passage, said open end being remote from said terminating metal wall.

11. The invention as defined in claim 6 further comprising in combinatinon tuning means coupled to said microwave energy output means for adjusting the voltage standing wave ratio of said oscillator output.

12. The invention as defined in claim 11 wherein said tuning means comprises a paddle.

13. The invention as defined in claim 11 wherein said tuning means comprises a tuned iris window.

14. The invention as defined in claim 6 further comprising:

first and second screw means of electrically conductive material, each said first and second screw means extending through a tapped opening in a corresponding one of said two opposed inner wall portions and having their ends in contact with a corresponding one of said negative terminals of said first and second diodes to ensure compressively supporting said mechanical series structure between said opposed wall portions and an electrical path between said negative terminals through said inner walls; and

third and fourth screw means of electrically conductive material, each said third and fourth screw means extending through a tapped opening in a corresponding one of said two additional opposed inner wall portions and having their ends in contact with a corresponding one of said negative terminals of said third and fourth diodes to ensure compressively supporting said second mechanical series structure between said additional opposed wall portions and an electrical path between all negative terminals through said inner walls.

15. The invention as defined in claim 10 wherein each of said post and said second post is of a predetermined length of less than the distance between said opposed inner wall portions of said passage and of a thickness dimension no more than one-quarter of the width of said waveguide passage.

16. The invention as defined in claim 15 wherein one of said posts is spaced from one adjacent inner wall by a predetermined distance, D, and wherein the other one of said posts is spaced from a second adjacent inner wall, opposite to said one adjacent wall, by the same predetermined distance, D.

17. The invention as defined in claim 6 wherein one of said posts is spaced from one adjacent inner wall by a predetermined distance, D, and wherein the other of said posts is spaced from a second adjacent inner wall, opposite to said one adjacent wall, by the same predetermined distance, D.

18. A solid state oscilLator comprising:

means forming a hollow rectangular waveguide passage, said passage being bordered by electrically conductive top, bottom, right side and left side walls;

a back wall to terminate said passage to microwave energy;

a plurality of Gunn diodes located in said passage, said plurality comprising a quantity 2N, where N is an even integer, and forming N diode pairs;

each said Gunn diode containing a first terminal of a first polarity and a second terminal of a second polarity;

an even numbered plurality of posts of electrically conductive material, said plurality of posts corresponding in number to one-half said quantity of diodes, (2N/2), and arranged to form N/2 pairs of posts and said posts being located in said passage spaced from each other and from said top, bottom, right side and left side walls and any one post of each pair of posts being spaced from said back wall by the same distance as the other post of said same pair of posts; and

with any one post of each pair of posts being spaced from the one of the said side walls most adjacent thereto by the same distance as the other post of said pair of posts is spaced from the other one of the said side wall most adjacent thereto;

said diodes of each pair of Gunn diodes in said plurality being, located at opposite ends of a corresponding one of said plurality of posts, each of said diodes of said pair having its first terminal electrically in common with the adjacent end of a corresponding post to form a plurality of mechanical series structures, said mechanical series structures being located in said passage spaced from said terminating back wall and from one another and each being supported in between said top and bottom walls;

said second polarity terminal of each diode being in contact electrically with said adjacent passage wall, whereby all of said second polarity terminals of said diodes are placed electrically in common;

a source of bias voltages for said diodes, said bias source having a first polarity output terminal and a second polarity output terminal;

means connecting said second polarity output terminal of said bias source electrically in common with said walls, and means placing said first polarity terminal of said bias source electrically in common with each of said plurality of posts.

19. The invention as defined in claim 18 further comprising means for positioning said back wall for changing the length of said passage.

20. The invention as defined in claim 19 wherein each said mechanical series structure is aligned substantially parallel with said side walls.

21. The invention as defined in claim 18 further comprising a plurality of electrically conductive screw means, said plurality corresponding in number to the number of Gunn diodes;

a corresponding plurality of tapped passages located in opposed walls of said waveguide aligned with the axis of a corresponding mechanical series structure;

each pair of screw means being located in opposed openings and having their ends in contact with said diodes whereby each said mechanical series structure is compressively supported in between said opposed walls and the second polarity terminal of each diode is thereby placed electrically in common with said walls.

22. The invention as defined in claim 18 wherein N comprises 2.

23. The invention as defined in claim 27 wherein the quantity N comprises 2.