Multimode coupling system including a funnel-shaped multimode coupler

• US 4,030,048 A
• Filed: 07/06/1976
• Issued: 06/14/1977
• Est. Priority Date: 07/06/1976
• Status: Expired due to Term

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: RCA Corporation (General Electric Company)
• Inventors: Foldes, Peter
• Primary Examiner(s): Gensler, Paul L.
• Application Number:
  US05/702,402
• Time in Patent Office: 343 Days
• Field of Search: 333/21 R, 333/21 A, 333/6, 333/9, 343/786, 343/852, 343/16 M, 343/100 PE
• US Class Current: 333/135
• CPC Class Codes: H01P 1/16 for mode selection, e.g. mode suppression or mode promotion; for mode conversion
• CPC Class Codes: H01P 1/2131 with combining or separating polarisations

Abstract

A multimode coupling system for coupling symmetrical waveguide mode signals and two or more tracking asymmetrical waveguide mode signals includes a funnel-shaped coupler with a plurality of coupling apertures located in the side wall thereof. A first four of these side wall apertures lie in a first common plane at a given distance from the small aperture end of the coupler. A second four of these apertures lie in a second common plane a second given distance from the small aperture end of the coupler. A first coupling circuit is provided between the first group of side wall apertures and an asymmetrical mode terminal, and a second coupling circuit is provided between the second four apertures in the second plane and a second asymmetrical mode terminal. Each coupling circuit includes a separate filter for each aperture, with the filters coupled to the first four side wall apertures adapted to pass signals at a first frequency band and with the filters coupled to the second four side wall apertures adapted to pass signals at a second frequency band.

Claims

1. A multimode coupling system for coupling symmetrical waveguide mode signals at one frequency band and asymmetrical waveguide mode signals at another frequency band comprising:

a generally funnel-shaped hollow coupler with the small aperture end adapted to pass said symmetrical mode signals and reflect asymmetrical mode signals and the large aperture end adapted to be coupled to free space,

an asymmetrical mode signal terminal,

first and second sidewall coupling apertures in the tapering side wall of said coupler with said first and second side wall coupling apertures at diametrically opposite surfaces of said coupler and in a given plane orthogonal to the axis of the coupler a given distance from the small aperture end of said coupler,

third and fourth side wall coupling apertures in the tapering side wall of said coupler with said third and fourth side wall coupling apertures at diametrically opposite surfaces of said coupler equally spaced from said first and second side wall apertures and in said first given plane at said first given distance from the small aperture end of said coupler, and

coupling means including a filter-polarizer coupled between each of said first, second, third and fourth sidewall apertures and said asymmetrical mode signal terminal characterized by a response to signals at said terminal for coupling equal portions of the signal energy at the terminal to said first, second, third and fourth apertures with the phase of the coupled signals at the first and third apertures being advanced 90°

relative to the phase of the signals at the second and fourth apertures,

said filter-polarizers characterized by a response to signals applied thereto at the terminal end thereof for exciting an elliptical polarized wave into the coupler, said given distance from said small aperture end of said coupler being selected together with the elliptical polarization characteristic of the filters to achieve a maximum coupling of asymmetric waveguide mode signal at a wanted polarization different from said elliptically polarized wave excited by the filter-polarizers.

2. The combination claimed in claim 1 wherein said wanted polarization is circular polarization and said given distance is such that the major axis of the excited elliptically-polarized waves and the major axis of the elliptically polarized wave reflected from the small aperture end at large aperture end is orthogonal in space and quadrature in phase.

3. The combination of claim 1 wherein said filter-polarizers are each square waveguide sections adapted to propagate signals in two orthogonal TE₁₀ modes with means for exciting and adjusting the relative magnitudes of two orthogonal TE₁₀ modes.

4. The combination of claim 1 wherein said filter-polarizer includes a crossed-slot aperture.

5. A multimode coupling system for coupling symmetrical waveguide mode signals at one frequency band and asymmetrical waveguide mode signals at a second and third frequency band comprising:

a generally funnel-shaped hollow coupler with the small aperture end adapted to pass signals in said symmetrical mode and reflect said signals in said asymmetrical mode and a large aperture end adapted to be coupled to free space,

first and second asymmetrical mode signal terminals,

a first set of four sidewall coupling apertures in the tapering sidewall of said coupler with said first set of sidewall apertures equally spaced from each other and in a first plane orthogonal to the axis of the coupler with said plane a first given distance from the small aperture end of said coupler,

a second set of four sidewall coupling apertures in the tapering sidewall of said coupler with said second set of sidewall coupling apertures equally spaced from each other in a second plane orthogonal to the axis of the coupler with said second plane a second given distance from the small aperture end of said coupler,

means including a first filter-polarizer adapted to pass signals at said second frequency band coupled between each of said first set of sidewall apertures and the first of said asymmetrical mode signal terminals characterized by a response to signals at said second frequency band at said first terminal to excite first elliptically polarized waves at said second frequency in said coupler, and

means including a second filter-polarizer adapted to pass signals at said third frequency band coupled between each of said second set of sidewall apertures and the second of said asymmetrical mode terminals characterized by a response to signals at said third frequency band at said second terminal to excite second elliptically polarized waves at said third frequency in said coupler.

6. The combination of claim 5 wherein said first and second given distances are unequal.

7. The combination of claim 5 wherein said first given distance is selected to achieve maximum coupling of asymmetrical waveguide mode signals at said second frequency band at a wanted polarization different from said first elliptically polarized waves and said second given distance is selected to achieve maximum coupling of an asymmetrical waveguide mode signals at said third frequency band at a wanted polarization different from said second elliptically polarized wave.

8. The combination of claim 7 wherein said wanted polarization is circular polarization.