COAXIAL WAVEGUIDE ANTENNA

• US 20130127678A1
• Filed: 11/23/2011
• Published: 05/23/2013
• Est. Priority Date: 11/23/2011
• Status: Active Grant

• Current Assignee: Raytheon Company (Rtx Corporation)
• Original Assignee: Raytheon Company (Rtx Corporation)
• Inventors: Chandler, Charles
• Granted Patent: US 9,325,074 B2
• Time in Patent Office: Days
• US Class Current: 343/731
• CPC Class Codes: H01Q 13/08 Radiating ends of two-conductor microwave transmission lines, e.g. of coaxial lines, of microstrip lines
• CPC Class Codes: H01Q 23/00 Antennas with active circuits or circuit elements integrated within them or attached to them

Abstract

Processes and systems for radiating electromagnetic energy from an open-ended coaxial cavity are described herein. An antenna assembly includes an open-ended coaxial radiator. The coaxial assembly includes an inner electrically conducting surface and an outer conductive surface spaced apart from and opposing the inner electrically surface. More than one radially aligned electromagnetic coupling modules are positioned at least partially within the coaxial waveguide along different rotation angles. Each of the different electromagnetic coupling modules samples a local electric field, amplifies the sampled field, and alters a phase of at least one of the amplified fields. The amplified, phase-adjusted coaxial fields are radiated from an open end of the coaxial cavity. Although described for transmission mode, the structure can be operated in receive mode by similarly detecting radiated electric fields, amplifying and applying a phase offset, and radiating the amplified, phase offset fields into an open-ended coaxial cavity.

Claims

1. An antenna assembly comprising:

an open-ended coaxial waveguide, comprising;

an inner electrically conducting surface having a substantially uniform cross section extending along a central axis; and

an outer electrically conducting surface having a substantially uniform cross section extending along the central axis, the outer conductive surface spaced apart from and opposing the inner electrically conducting surface;

a first electromagnetic coupling module disposed at least partially within the coaxial waveguide and aligned substantially along a radius;

a second electromagnetic coupling module disposed at least partially within the coaxial waveguide and aligned substantially along a different radius, each of the first and second electromagnetic coupling modules comprising;

a respective pair of opposing transducers, each transducer adapted to convert between an electromagnetic field and at least one of a voltage and a current; and

a respective electronic circuit in electrical communication between the respective pair of opposing transducers, at least one of the respective electronic circuits comprising a phase-adjusting element adapted to introduce a phase difference between the at least one of a voltage and a current of the first and second electromagnetic coupling modules.

2. The antenna assembly of claim 1, wherein the first and second electromagnetic coupling modules are disposed along diametrically opposing radii and the phase adjusting element introduces a phase difference of +/−

180 degrees.

3. The antenna assembly of claim 2, wherein each of the transducers comprises a finline structure adapted for efficiently coupling a radial component of an electric field.

4. The antenna assembly of claim 3, wherein each of the transducers is selected from the group consisting of:

dipoles;

loops;

finlines;

antipodal finlines;

notch;

travelling wave structures; and

combinations thereof.

5. The antenna assembly of claim 2, further comprising:

third and fourth electromagnetic coupling modules, each disposed at least partially within the coaxial waveguide and along diametrically opposing radii arranged orthogonal to diametrically opposing radii of the first and second electromagnetic coupling modules, each of the third and fourth electromagnetic coupling modules comprising;

a respective pair of opposing transducers, each transducer adapted to convert between an electromagnetic field and at least one of a voltage and a current, and

a respective electronic circuit in electrical communication the respecting pair of transducers, at least one of the respective electronic circuits comprising a phase adjusting element introducing a +/−

180 degree phase difference between the at least one of a voltage and a current of the third and fourth electromagnetic coupling modules.

6. The antenna assembly of claim 5, wherein each phase adjusting element introduces a +/−

90 degrees phase difference between the respective at least one of a voltage and a current of radially adjacent ones of the electromagnetic coupling modules.

7. The antenna assembly of claim 1, wherein at least one of the electronic circuits comprise a respective amplifier adapted to amplify a respective one of the at least one of a voltage and a current.

8. The antenna assembly of claim 1, further comprising:

a coaxial transmission line port axially aligned with the coaxial waveguide; and

an axially aligned, tapered coaxial waveguide coupled between one end of the open-ended coaxial waveguide and the coaxial transmission line port.

9. The antenna assembly of claim 1, wherein a cross section of the open-ended coaxial cavity is substantially circular.

10. The antenna assembly of claim 1, wherein the phase-adjusting element is selected from the group consisting of:

reactance-based phase shifters;

switched-line phase shifters;

vector-modulator-based phase shifters;

digital phase shifters; and

combinations thereof.

11. The antenna assembly of claim 1, wherein the open end of the coaxial waveguide is defined substantially in a plane perpendicular to the central axis.

12. The antenna assembly of claim 1, further comprising an axial protrusion of the inner conducting surface extending beyond a terminal end of the outer conducting surface.

13. The antenna assembly of claim 12, wherein a shape of the protrusion is selected from the group of shapes consisting of:

cylinders;

cones;

paraboloids;

truncated cones;

truncated paraboloids;

prisms;

pyramids; and

combinations thereof.

14. A method for radiating electromagnetic energy, comprising:

amplifying selectively a first radial component of a transverse electromagnetic field within an open-ended coaxial waveguide;

amplifying selectively a second radial component of the transverse electromagnetic field, angularly offset from the first radial component;

applying a relative phase offset between the first and second amplified radial components of the transverse electromagnetic field; and

directing each of the amplified radial components toward an open end of the open-ended coaxial waveguide, wherein the amplified radial components establish far-field radiation.

15. The method of claim 14, wherein the first and second radial components are selected along diametrically opposing radii, and wherein the act of applying a relative phase offset comprises applying a +/−

180 degree offset between the first and second amplified radial components.

16. The method of claim 14, further comprising:

amplifying selectively a third radial component of the transverse electromagnetic field angularly offset from the first and second radial components;

amplifying selectively a fourth radial component of the transverse electromagnetic field angularly offset from the first, second and third radial components;

applying a relative phase offset between the third and fourth amplified radial components of the transverse electromagnetic field; and

directing each of the amplified radial components toward an open end of the open-ended coaxial waveguide, wherein the amplified radial segments establish far-field radiation.

17. The method of claim 14, wherein the third and fourth radial components are selected along diametrically opposing radii, and applying a relative phase offset comprises applying a +/−

180 degree offset between the first and second amplified radial components.

18. The method of claim 14, wherein applying the relative phase difference between the first and second electromagnetic coupling modules and applying the relative phase difference between the third and fourth electromagnetic coupling modules, comprises applying a relative phase difference between the first and the third electromagnetic coupling modules of approximately +/−

90 degrees.

19. An antenna assembly, comprising:

means for amplifying selectively a first radial component of a transverse electromagnetic field within an open-ended coaxial waveguide;

means for amplifying selectively a second radial component of the transverse electromagnetic field, angularly offset from the first radial component;

means for applying a relative phase offset between the first and second amplified radial components of the transverse electromagnetic field; and

means for directing each of the amplified radial components toward an open end of the open-ended coaxial waveguide, wherein the amplified radial components establish far-field radiation.