Coax-to-radial transition

• US 3,942,130 A
• Filed: 12/30/1974
• Issued: 03/02/1976
• Est. Priority Date: 12/30/1974
• Status: Expired due to Term

• Current Assignee: Hughes Aircraft Company (Rtx Corporation)
• Original Assignee: Hughes Aircraft Company (Rtx Corporation)
• Inventors: Harp, Robert S.
• Primary Examiner(s): Gensler, Paul L.
• Application Number:
  US05/537,820
• Time in Patent Office: 428 Days
• Field of Search: 333/6, 333/9, 333/24 R, 333/33-35, 333/21 R, 333/95 R, 333/96, 333/22 R, 333/97 R, 333/98 R, 330/4.9, 330/34, 330/53, 331/56, 331/101, 343/754, 343/771
• US Class Current: 330/287
• CPC Class Codes: H01P 5/08 for linking dissimilar lines or devices H01P1/16, H01P5/04 take precedence; linking lines of the same kind but with different dimensions H01P5/02

Abstract

A transmission line transition for coupling together a coaxial transmission line and a parallel plane radial transmission line, the transition including upper and lower circular plates having conforming inner curved surfaces spaced from each other to define an air dielectric transmission line comprising, in succession, a coaxial air line section, a transition air line section, and a radial air line section.

Claims

1. A transmission line transition for coupling together a coaxial transmission line and a parallel plane radial transmission line, comprising:

a lower circular plate having an upper surface of revolution generated by a smooth curve segment concave with respect to an axis of revolution and rotated about said axis, one end of said curve segment being relatively closely spaced from said axis while the other end of said curve segment being approximately parallel to a line perpendicular to said axis;

an upper circular plate having a lower surface of revolution conforming to the shape of said upper surface of said lower circular plate; and

separation means disposed between said upper and lower surfaces of revolution for maintaining a desired uniform separation distance between said surfaces and thereby defining successively a coaxial air line section, a smooth transition air line section, and a radial air line section coextensive with said plates.

2. The transition according to claim 1, also comprising coax coupling means including a coaxial terminal connector mounted on said upper circular plate coaxial with said axis, an inner conductor of said connector being electrically connected to said lower circular plate at the portion of said surface of revolution generated by said one end of said curve line segment, and an outer conductor thereof being electrically connected to said upper circular plate for electromagnetically coupling energy from said coaxial terminal connector to said coaxial air line section.

3. The transition according to claim 1, wherein said curved segment has a constant radius.

4. The transition according to claim 3, wherein said plates have a diameter of approximately 8 inches and said constant radius is approximately 2 inches.

5. The transition according to claim 3, wherein said curve segment is a circular quadrant.

6. The transition according to claim 1, also comprising a power absorbing structure disposed symmetrically about said axis in said radial air line section.

7. The transition according to claim 1, wherein said spacing means includes a conductive annular ring disposed adjacent the outer periphery of said circular plates.

8. The transition according to claim 7, wherein said annular ring has a width of approximately 1 inch and has a length dimension of approximately 0.080 inch.

9. The transition according to claim 7, also comprising negative resistance means including a plurality of negative resistance elements disposed symmetrically about said axis in said radial air line section spaced from the inner peripheral edge of said conductive annular ring.

10. The transition according to claim 9, also comprising mode filter means including radially extending grooves in said upper surface in said radial air line section symmetrically between said negative resistance elements, said grooves being partially filled with an energy-absorbing lossy material.

11. The transition according to claim 10, wherein said grooves are approximately one-quarter wavelength deep with respect to the wavelength of electromagnetic energy propagating in said air line sections.

12. The transition according to claim 9, also comprising impedance matching means including an annular ridge depending from said lower surface in said radial air line section upstream of said negative resistance elements for matching the impedance of said radial air line section to said negative resistance elements.

13. The transition according to claim 12, wherein said ridge is spaced from said negative resistance elements by approximately one-quarter wavelength.

14. The transition according to claim 9, wherein said negative resistance elements are IMPATT diodes and further comprising means associated with said plates for introducing to said diodes an operating bias voltage potential.

15. The transition according to claim 9, wherein said negative resistance elements are GUNN diodes, and further comprising means associated with said plates for introducing to said diodes an operating bias voltage potential.