ELLIPTICAL-TO-RECTANGULAR WAVEGUIDE TRANSITION

• US 3,818,383 A
• Filed: 02/27/1973
• Issued: 06/18/1974
• Est. Priority Date: 02/27/1973
• Status: Expired due to Term

• Current Assignee: Frank R. Willis
• Original Assignee: Frank R. Willis
• Inventors: Willis, Frank R.
• Primary Examiner(s): Gensler, Paul L.
• Application Number:
  US05/336,195
• Time in Patent Office: 476 Days
• Field of Search: 333/21R,21A,34,98R
• US Class Current: 333/21.00R
• CPC Class Codes: H01P 5/082 Transitions between hollow waveguides of different shape, e.g. between a rectangular and a circular waveguide

Abstract

An elliptical-to-rectangular waveguide transition has a passage of the cross-sectional shape formed by concave top and bottom walls of generally elliptical form and side walls of no concavity. The curvature of the top and bottom walls varies continuously along the length to produce matching to the shapes at the respective ends. The side walls are those of the rectangular end at that point and diminish to zero height at the elliptical end. Non-linear tapering of cross-sectional dimensions is employed to minimize reflections at the ends.

Claims

1. In a waveguide transition for dominant-mode transmission of the type having a passage rectangular at one end, generally elliptical at the other end, and of continuously varying crosssection between said ends, the improvement wherein the crosssection at any point between the ends has concave top and bottom walls and straight side walls the concave curvature of said top and bottom walls extending continuously from one of said side walls to the other, the top and bottom walls each having concave curvature continuously increasing from straightness at the rectangular end to the form of semi-ellipses forming the elliptical end with the longitudinal configuration of the transition formed by said top and bottom walls in the E-plane forming a smoothly continuous curve represented by an equation which has a second derivative that changes sign along the length of the transition, and which has a first derivative that is zero at both ends of the transition so that there are no angular discontinuities at the ends of said top and bottom walls, the side walls being tapered in height and having their top and bottom edges meeting at the elliptical end.

2. The transition of claim 1 wherein the rectangular and elliptical ends of said passage have different transverse dimensions, and the longitudinal configuration of the transition formed by said side walls in the H-plane forms a smoothly continuous curve represented by an equation which has a first derivative that is zero at the rectangular end of the transition so that there are no angular discontinuities at the rectangular ends of said side walls.

3. The transition of claim 1 wherein the distance X of each sidewall from the centerline at any longitudinal point is substantially equal to a - (a - A/2) cos (( pi /2) (z/L)) where a is half the major axis of the elliptical end, A is the width of the rectangular end, z is the distance of the point from the rectangular end, and L is the total length.

4. The transition of claim 1 wherein the top and bottom walls are of the cross-sectional general form of segments of ellipses tapering in eccentricity along the length of the transition.

5. The transition of claim 4 wherein the passage at any distance z from the rectangular end has an E-plane dimension 2D substantially in accordance with D (B/2) cos2 ( pi z/2L) + b sin2 ( pi z/2L) where L is the total length of the transition, B is the E-plane dimension of the rectangular end and b is half the E-plane dimension of the elliptical end.

6. The transition of claim 5 wherein the passage at any distance z from the rectangular end has top and bottom walls which are substantially segments of the ellipse (x2/C2) + (y2/D2) 1 where C a/sin ( pi z/2 L) '"'"''"'"''"'"''"'"'a'"'"''"'"''"'"''"'"' being half the H-plane dimension of the elliptical end, and D (B/2) cos2 ( pi z/2 L) + b sin2 ( pi z/2 L)

7. The transition of claim 6 wherein the spacing 2X between the side walls and any distance z from the rectangular end is substantially equal to twice the quantity a - (a - A/2) cos ( pi /2) (z/L) , '"'"''"'"''"'"''"'"'A'"'"''"'"''"'"''"'"' being the H-plane dimension of the rectangular end.

8. In a waveguide transition for dominant-mode transmission of the type having a passage rectangular at one end, generally elliptical at the other end, and of continuously varying cross-section between said ends, the improvement wherein the cross-section at any point between the ends has concave top and bottom walls and convex side walls, the concave curvature of said top and bottom walls extending continuously from one of said side walls to the other, the top and bottom walls each having concave curvature continuously increasing from straightness at the rectangular end to the form of semi-ellipses forming the elliptical end with the longitudinal configuration of the transition formed by said top and bottom walls in the E-plane forming a smoothly continuous curve represented by an equation which has a second derivative that changes sign along the length of the transition, and which has a first derivative that is zero at both ends of the transition so that there are no angular discontinuities at the ends of said top and bottom walls, the side walls being tapered in height and having their top and bottom edges meeting at the elliptical end.

9. The transition of claim 8 wherein the rectangular and elliptical ends of said passage have different transverse dimensions, and the longitudinal configuration of the transition formed by said side walls in the H-plane forms a smoothly continuous curve represented by an equation which has a first derivative that is zero at the rectangular end of the transition so that there are no angular discontinuities at the rectangular ends of said side walls.