Multiplexer/demultiplexer structures and methods

• US 6,201,949 B1
• Filed: 05/22/1998
• Issued: 03/13/2001
• Est. Priority Date: 05/22/1998
• Status: Expired due to Term

• Current Assignee: Com DEV International Limited (Honeywell International Inc.)
• Original Assignee: The Boeing Co.
• Inventors: Kich, Rolf, Gray, Devon J.
• Primary Examiner(s): LEE, BENNY T
• Application Number:
  US09/083,456
• Time in Patent Office: 1,026 Days
• Field of Search: 333/126, 333/129, 333/135, 455/13.1, 455/13.3, 455/12.1, 370/281, 370/295, 370/316, 370/319
• US Class Current: 455/12.1
• CPC Class Codes: H04B 7/18519 Operations control, administration or maintenance

Abstract

A multiplexer/demultiplexer structure is provided which multiplexes multiple channel signals through a common tee of a tee/manifold mulitplexer arrangement. This multiplexing significantly reduces the number of tees required for a given number of multiplexed channels. Accordingly, mulitplexer/demulitplexer design time is reduced and fabricated multiplexers/demultiplexers are lighter, smaller and less expensive. The tee multiplexing is facilitated with multiple access apertures that are isolated by a septum. The septum forms reduced-height waveguides which define a path length between apertures that is sufficient to significantly reduce higher-order modes and, therefore, apeture interactions.

Claims

1. A multiplexer/demultiplexer, comprising:

a primary waveguide;

a secondary waveguide joined to said primary waveguide and providing first and second apertures for signal access to said secondary waveguide;

a first waveguide filter coupled through said first aperture to said secondary waveguide;

a second waveguide filter coupled through said second aperture to said secondary waveguide; and

a septum positioned between said first and second apertures to provide signal isolation between said first and second apertures.

2. The multiplexer/demultiplexer of claim 1, wherein:

said secondary waveguide has dimensions that allow propagation of signals which have an average guide wavelengthλ

_gavg;

said secondary waveguide has a short-circuited end; and

said septum extends away from said short-circuited end by a distance greater than (⅛

)λ

_gavg.

3. The multiplexer/demultiplexer of claim 1, wherein:

said secondary waveguide has dimensions that allow propagation of signals which have an average guide wavelength λ

_gavg;

said secondary waveguide has a short-circuited end; and

said septum extends away from said short-circuited end by a distance substantially equal to (¼

) λ

_gavg.

4. The multiplexer/demultiplexer of claim 1, wherein:

said septum divides a portion of said secondary waveguide into first and second subwaveguides; and

each of said first and second apertures is positioned to provide access to a respective one of said first and second subwaveguides.

5. The multiplexer/demultiplexer of claim 1, wherein said primary waveguide and said secondary waveguide are rectangular waveguides.

6. The multiplexer/demultiplexer of claim 5, wherein said primary waveguide and said secondary waveguide are configured to define an E-plane junction.

7. The multiplexer/demultiplexer of claim 5, wherein said primary waveguide and said secondary waveguide are configured to define an H-plane junction.

8. The multiplexer/demultiplexer of claim 1, wherein said primary waveguide and said secondary waveguide are circular waveguides.

9. The multiplexer/demultiplexer of claim 1, wherein said first and second waveguide filters are cylindrical filters.

10. The multiplexer/demultiplexer of claim 1, wherein said first and second waveguide filters are rectangular filters.

11. The multiplexer/demultiplexer of claim 1, wherein said first and second waveguide filters are spherical filters.

12. The multiplexer/demultiplexer of claim 1, wherein said primary waveguide has a short-circuited end and said primary waveguide also has an open-circuited end which provides signal access to said secondary waveguide.

13. A spacecraft communication system, comprising:

a spacecraft; and

a transponder carried by said spacecraft, said transponder having;

a) a receive antenna to receive input communication signals in a receive frequency band;

b) a transmit antenna to radiate output communication signals in a transmit frequency band; and

c) a frequency converter coupled between said receive antenna and said transmit antenna to convert said receive frequency band to said transmit frequency band, said frequency converter including;

1) a demultiplexer for splitting said receive frequency band into a plurality of subbands;

2) a plurality of amplifiers, each coupled to amplify input communication signals in a respective one of said subbands; and

3) a multiplexer for combining said subbands into said transmit frequency band wherein said demultiplexer and said multiplexer each include;

a) a primary waveguide;

b) a secondary waveguide joined to said primary waveguide and providing first and second apertures for signal access to said secondary waveguide;

c) a first waveguide filter coupled through said first aperture to said secondary waveguide;

d) a second waveguide filter coupled through said second aperture to said secondary waveguide; and

e) a septum positioned between said first and second apertures to provide signal isolation between said first and second apertures.

14. The communication system of claim 13, wherein in each of said mulitplexer and said demulitplexer:

said secondary waveguide has dimensions that allow propagation of signals which have an average guide wavelength λ

_gavg;

said secondary waveguide has a short-circuited end; and

said septum extends away from said short-circuited end by a distance greater than (⅛

)λ

_gavg.

15. The communication system of claim 13, wherein in each of said mulitplexer and said demulitplexer:

said secondary waveguide has dimensions that allow propagation of signals which have an average guide wavelength λ

_gavg;

said secondary waveguide has a short-circuited end; and

said septum extends away from said short-circuited end by a distance substantially equal to (¼

)λ

_gavg.

16. The communication system of claim 13, wherein in each of said mulitplexer and said demulitplexer:

said septum divides a portion of said secondary waveguide into first and second subwaveguides; and

each of said first and second apertures is positioned to provide access to a respective one of said first and second subwaveguides.

17. The communication system of claim 13, wherein, in each of said mulitplexer and said demulitplexer, said primary waveguide and said secondary waveguide are configured to define an E-plane junction.

18. The communication system of claim 13, wherein, in each of said mulitplexer and said demulitplexer, said primary waveguide and said secondary waveguide are configured to define an H-plane junction.

19. A transponder, comprising:

a receive antenna to receive input communication signals in a receive frequency band;

a transmit antenna to radiate output communication signals in a transmit frequency band; and

a frequency converter coupled between said receive antenna and said transmit antenna to convert said receive frequency band to said transmit frequency band, said frequency converter including;

1) a demultiplexer for splitting said receive frequency band into a plurality of subbands;

2) a plurality of amplifiers, each coupled to amplify input communication signals in a respective one of said subbands; and

3) a multiplexer for combining said subbands into said transmit frequency band wherein said demultiplexer and said multiplexer each include;

a) a primary waveguide;

b) a secondary waveguide joined to said primary waveguide and providing first and second apertures for signal access to said secondary waveguide;

c) a first waveguide filter coupled through said first aperture to said secondary waveguide;

d) a second waveguide filter coupled through said second aperture to said secondary waveguide; and

e) a septum positioned between said first and second apertures to provide signal isolation between said first and second apertures.

20. The transponder of claim 19, wherein, in each of said mulitplexer and said demulitplexer, said primary waveguide and said secondary waveguide are configured to define an E-plane junction.

21. The transponder of claim 19, wherein, in each of said mulitplexer and said demulitplexer, said primary waveguide and said secondary waveguide are configured to define an H-plane junction.

22. The transponder of claim 19, wherein in each of said mulitplexer and said demulitplexer:

said secondary waveguide has dimensions that allow propagation of signals which have an average guide wavelength λ

_gavg;

said secondary waveguide has a short-circuited end; and

said septum extends away from said short-circuited end by a distance greater than (⅛

)λ

_gavg.

23. The transponder of claim 19, wherein in each of said mulitplexer and said demulitplexer:

said secondary waveguide has dimensions that allow propagation of signals which have an average guide wavelength λ

_gavg;

said secondary waveguide has a short-circuited end; and

said septum extends away from said short-circuited end by a distance substantially equal to (¼

)λ

_gavg.

24. The transponder of claim 19, wherein in each of said mulitplexer and said demulitplexer:

said septum divides a portion of said secondary waveguide into first and second subwaveguides; and

each of said first and second apertures is positioned to provide access to a respective one of said first and second subwaveguides.