Hybrid mode waveguide and feedhorn antennas

• US 4,231,042 A
• Filed: 08/22/1979
• Issued: 10/28/1980
• Est. Priority Date: 08/22/1979
• Status: Expired due to Term

• Current Assignee: Bell Telephone Laboratories, Inc. (Nokia Corporation)
• Original Assignee: Bell Telephone Laboratories, Inc. (Nokia Corporation)
• Inventors: Turrin, Richard H.
• Primary Examiner(s): Lieberman, Eli
• Application Number:
  US06/068,621
• Time in Patent Office: 433 Days
• Field of Search: 343/783, 343/786, 333/239, 333/241, 333/242, 333/21 R
• 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 3/127 with a circular, elliptic, or parabolic cross-section
• CPC Class Codes: H01Q 13/0208 Corrugated horns waveguide mouth antenna with corrugated flange H01Q13/065; manufacturing details H01Q13/0283

Abstract

The present invention relates to a hybrid mode waveguide or feedhorn antenna for transforming the TE₁₁ mode into the HE₁₁ mode. The waveguide or feedhorn comprises a circular waveguide including a tubular section at the TE₁₁ mode entrance port changing in the antenna configuration to a conical section that flares outward to the feedhorn mouth, and a spiro-helical projection bonded to the interior surface of the waveguide. In a first arrangement, the spiro-helical projection comprises an initially flattened dielectrically coated wire that gradually returns to a rounded configuration in closely spaced helical turns after which the spacings between turns gradually increase linearly in the tubular section and then continue with uniform spacings in the conical section. In a second arrangement, multiple layers of closely-wound helically wound dielectrically coated wires, which layers gradually taper down to a single layer, can replace the closely spaced flattened-to-round wire section of the first arrangement.

Claims

1. A hybrid mode feedhorn antenna comprising:

a hollow waveguide body including an inner surface and comprises a first section (12) of uniform cross-section which converts into a second section (14) that flares outward from one end of the first section to form a mouth of the feedhorn antenna

characterized in that

the feedhorn antenna further comprises;

a spiro-helical projection (18, FIGS. 1-3;

38, FIG.

     4) comprising a helically wound dielectrically coated wire bonded to the waveguide body with a dielectric layer, said wire being helically wound in closely spaced turns which abut one another starting at the end of the first section further from the second section and covering a first portion (II-IV, FIG. 2;

30, FIG.

     4) of the inner surface of the first section in a manner capable of providing a smooth transition for a TE₁₁ mode signal propagating therethrough, the helical windings continuing in a second portion (V, FIG. 2;

32, FIG.

     4) of the first section adjacent said first portion with turns which gradually have the spacing therebetween increased in a linear manner which is capable of converting the TE₁₁ mode of a signal propagating therethrough into a HE₁₁ mode, and the helical windings continuing in the remaining portion of the feedhorn antenna with a uniform pitch.

2. A hybrid mode feedhorn antenna according to claim 1

characterized in that

the spiro-helical projection (18) in said first portion (II-IV, FIG. 2) of the first section is formed from a dielectrically coated wire which is initially flattened on two opposing surfaces and edge wound in abutting helical turns, the wire gradually changing to a rounded cross-section as the helix approaches said second portion of the first section.

3. A hybrid mode feedhorn antenna according to claim 1

characterized in that

the spiro-helical projection (18) in said first portion (30, FIG. 4) further includes multiple abutting layers of helically wound dielectrically coated wires (40, FIG. 4) disposed on the surface of said first helically wound wire nearest the inner surface of the first section of the waveguide body, the successive layers of helically wound dielectrically coated wires forming said multiple layers having lengths, which progress inwards from the end of the first section furthest from the conical section, to effect an edge on said multiple layers which slopes inward to said first helically wound wire in the direction of said second portion of the first section.

4. A hybrid mode feedhorn antenna according to claim 1, 2 or 3

characterized in that

the thickness of the wire and the dielectric layer being an approximate quarter wavelength at the lowest operating frequency of the feedhorn antenna.

5. A hybrid mode waveguide comprising:

a hollow waveguide body including an inner surface

characterized in that

the hybrid mode waveguide further comprises;

a helical projection (18, FIG.

     5) comprising a helically wound dielectrically coated wire bonded to the waveguide body with a dielectric layer, said wire being helically wound in closely spaced turn which abut one another starting at one end of the waveguide body and covering a first portion of the inner surface of the waveguide body in a manner capable of providing a smooth transition for a TE₁₁ mode signal propagating therethrough, the helical windings continuing in a second portion of the waveguide body adjacent said first portion with turns which gradually have the spacing therebetween increased in a linear manner which is capable of converting the TE₁₁ mode of a signal propagating therethrough into a HE₁₁ mode, and the helical windings continuing in the remaining portion of the waveguide body with a uniform pitch.

6. A hybrid mode waveguide according to claim 5

characterized in that

the helical projection (18) in said first portion of the waveguide body is formed from a dielectrically coated wire which is initially flattened on two opposing surfaces and edge wound in abutting helical turns, the wire gradually changing to a rounded cross-section as the helix approaches said second portion of the waveguide body.

7. A hybrid mode waveguide according to claim 5

characterized in that

the helical projection (18) in said first portion of the waveguide body further includes multiple abutting layers of helically wound dielectrically coated wires disposed on the surface of said first helically wound wire nearest the inner surface of the waveguide body, the successive layers of helically wound wires forming said multiple layers having lengths, which progress inwards from said one end of the waveguide, to effect an edge on said multiple layers which slopes inward to said first helically wound wire in the direction of said second portion of the waveguide body.

8. A hybrid mode waveguide according to claim 5, 6 or 7

characterized in that

the thickness of the wire and the dielectric layer being an approximate quarter wavelength at the lowest operating frequency of the waveguide.

9. A waveguide for converting a TE₁₁ mode signal into a HE₁₁ mode signal comprising:

a hollow waveguide section comprising an inner surface

characterized in that

the waveguide further comprises;

a mode conversion means (III-V, FIG. 2;

72, FIG.

     5) comprising a helically wound dielectrically coated wire bonded to the inner surface of the waveguide section with a dielectric layer, said wire being wound in closely spaced turns which abut one another starting at one end of the waveguide section and covering a first portion of the inner surface of the waveguide section in a manner capable of providing a smooth transition for the TE₁₁ mode signal propagating therethrough, the helical windings continuing in a second portion of the waveguide section adjacent said first portion with turns which gradually have the spacing therebetween increased in a linear manner to convert the TE₁₁ mode signal to the HE₁₁ mode signal.

10. A waveguide according to claim 9

characterized in that

the helical projection (18) in said first portion of the waveguide section is formed from a dielectrically coated wire which is initially flattened on two opposing surfaces and edge wound in abutting helical turns, the wire gradually changing to a rounded cross-section as the helix approaches said second portion of the waveguide section.

11. A waveguide according to claim 9

characterized in that

the helical projection (18) in said first portion of the waveguide section further includes multiple abutting layers of helically wound dielectrically coated wires disposed on the surface of said first helically wound wire nearest the inner surface of the waveguide section, the successive layers of helically wound wires forming said multiple layers having lengths, which progress inwards from said one end of the waveguide section, to effect an edge on said multiple layers which slopes inward to said first helically wound wire in the direction of said second portion of the waveguide section.

12. A waveguide in accordance with claim 9, 10 or 11

characterized in that

the thickness of the wire and the dielectric layer being an approximate quarter wavelength at the lowest operating frequency of the waveguide.