Flared microwave feed horns and waveguide transitions

• US 4,604,627 A
• Filed: 01/11/1984
• Issued: 08/05/1986
• Est. Priority Date: 01/11/1984
• Status: Expired due to Term

• Current Assignee: Andrew Corporation (CommScope Holding Company, Inc.)
• Original Assignee: Andrew Corporation (CommScope Holding Company, Inc.)
• Inventors: Knop, Charles M., Saad, Saad S.
• Primary Examiner(s): Lieberman, Eli
• Application Number:
  US06/569,789
• Time in Patent Office: 937 Days
• Field of Search: 343/786, 343/840, 343/912
• US Class Current: 343/786
• CPC Class Codes: H01P 1/16 for mode selection, e.g. mode suppression or mode promotion; for mode conversion
• CPC Class Codes: H01P 5/024 between hollow waveguides
• CPC Class Codes: H01Q 13/02 Waveguide horns
• CPC Class Codes: H01Q 19/132 Horn reflector antennas; Off-set feeding

Abstract

A horn-reflector antenna comprising a paraboloidal reflector for transmitting and receiving microwave energy, and a flared feed horn for guiding microwave energy to and from the reflector, the longitudinal shape of at least a section of the horn at the end where the horn begins to flare outwardly being defined by the equation ##EQU1## where R is the transverse dimension from the longitudinal axis of the horn to the side wall of the horn 1 is the axial distance along the horn measured from the end where the horn begins to flare outwardly, R₁ and R₂ are the radii of the horn at opposite ends of the horn section defined by the equation, L is the axial length of the horn section defined by the equation, and the exponent p has a value greater than two and less than about 7, to effect a substantial reduction in the TM₁₁ mode level.

Claims

1. A horn-reflector antenna comprising

a paraboloidal reflector for transmitting and receiving microwave energy, and

a flared feed horn for guiding microwave energy to and from said reflector, the longitudinal shape of at least a section of said horn at the end where the horn begins to flare outwardly being defined by the equation ##EQU5## where R is the transverse dimension from the longitudinal axis of the horn to the side wall of the horn, l is the axial distance along the horn measured from said end where the horn begins to flare outwardly, R₁ and R₂ are the radii of the horn at opposite ends of the horn section defined by said equation, L is the axial length of the horn section defined by said equation, and the exponent p has a value greater than two and less than about 7, to effect a substantial reduction in the TM₁₁ mode level.

2. A horn-reflector antenna as set forth in claim 1 wherein said exponent p has a value sufficiently greater than two that said antenna has a TM₁₁ mode level substantially below the TM₁₁ mode level of the same antenna with a hyperbolic (p=2) longitudinal shape along the length L between the radii R₁ and R₂.

3. A horn-reflector antenna as set forth in claim 2 wherein said antenna has, at 6 GHz, a TM₁₁ mode level at least 5 dB below the TM₁₁ mode level of the same antenna with a hyperbolic longitudinal shape.

4. A horn-reflector antenna as set forth in claim 1 wherein the exponent p has a value of at least 2.5.

5. A horn-reflector antenna as set forth in claim 1 wherein the exponent p has a value greater than about 2.5.

6. A horn-reflector antenna as set forth in claim 1 wherein the exponent p has a value within the range from about 4 to about 6.7.

7. A method of reducing the TM₁₁ mode level in a horn reflector antenna having a paraboloidal reflector for transmitting and receiving microwave energy, and a smooth-walled, flared feed horn for guiding microwave energy to and from said reflector, said method comprising shaping a section of said horn at the end where the horn begins to flare outwardly so that the inside wall of said section is defined by the equation ##EQU6## where R is the transverse dimension from the longitudinal axis of the horn to the side wall of the horn, l is the axial distance along the horn measured from said end where the horn begins to flare outwardly, R₁ and R₂ are the radii of the horn at opposite ends of the horn section defined by said equation, L is the axial length of the horn section defined by said equation, and the exponent p has a value greater than two and less than about 7, to effect a substantial reduction in the TM₁₁ model level.

8. A method as set forth in claim 7 wherein said exponent p has a value sufficiently greater than two that said antenna has a TM₁₁ mode level substantially below the TM₁₁ mode level of the same antenna with a hyperbolic (p=2) longitudinal shape along the length L between the radii R₁ and R₂.

9. A method as set forth in claim 8 wherein said antenna has, at 6 GHz, a TM₁₁ mode level at least 5 dB below the TM₁₁ mode level of the same antenna with a hyperbolic longitudinal shape.

10. A method as set forth in claim 7 wherein the exponent p has a value of at least 2.5.

11. A method as set forth in claim 7 wherein the exponent p has a value greater than about 2.5.

12. A method as set forth in claim 7 wherein the exponent p has a value within the range from about 4 to about 6.7.