Beam forming network for feeding short wall slotted waveguide arrays

• US 9,612,317 B2
• Filed: 08/17/2014
• Issued: 04/04/2017
• Est. Priority Date: 08/17/2014
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Google Inc. (Alphabet Inc.)
• Inventors: Izadian, Jamal, Smith, Russell
• Primary Examiner(s): Barker, Matthew M
• Application Number:
  US14/461,417
• Publication Number:
  US 20160047893A1
• Time in Patent Office: 961 Days
• CPC Class Codes: G01S 13/02 Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
• CPC Class Codes: G01S 13/931 of land vehicles
• CPC Class Codes: G01S 7/03 Details of HF subsystems specially adapted therefor, e.g. common to transmitter and receiver
• CPC Class Codes: G01S 7/032 Constructional details for solid-state radar subsystems
• CPC Class Codes: H01P 1/182 Waveguide phase-shifters H01P1/181, H01P1/185, H01P1/19 take precedence
• CPC Class Codes: H01P 5/182 the waveguides being arranged in parallel
• CPC Class Codes: H01Q 21/0043 Slotted waveguides combination with horns H01Q13/0233
• CPC Class Codes: H01Q 21/005 Slotted waveguides arrays
• CPC Class Codes: H01Q 3/40 with phasing matrix
• CPC Class Codes: H04B 7/0617 for beam forming

Abstract

An example method for a beamforming network for feeding short wall slotted waveguide arrays. The beamforming network may include six beamforming network outputs, where each beamforming network output is coupled to one of a set of waveguide inputs. Further, the beamforming network may include a cascaded set of dividers configured to split electromagnetic energy from a beamforming network input to the six phase-adjustment sections. The cascade may include a first level of the cascade configured to split the electromagnetic energy from the beamforming network input into two first-level beamforming waveguides, a second level configured to split the electromagnetic energy from each of two first-level beamforming waveguides into two respective second-level beamforming waveguides, and a third level of the cascade configured to split the electromagnetic energy from one of two respective second-level beamforming waveguides into two respective third-level beamforming waveguides.

Claims

1. A radar system comprising:

six radiating waveguides located in a waveguide layer, each having a radiating waveguide input, wherein each radiating waveguide has a height and a width that are equal to that of each other radiating waveguide, wherein the radiating waveguides are aligned on a plane defined by a center of the width of the radiating waveguide and a length of the radiating waveguide, and wherein each radiating waveguide is coupled to at least one radiating element located in a radiating layer; and

a beamforming network located in the waveguide layer, wherein the beamforming network comprises;

a beamforming network input,

six beamforming network outputs, wherein each beamforming network output is coupled to one of the radiating waveguide inputs,

six phase-adjustment sections, wherein each of the phase-adjustment sections is coupled to a respective one of six cascade outputs,

a cascaded set of dividers configured to split electromagnetic energy from the beamforming network input to the six phase-adjustment sections, wherein the cascade comprises;

a first level of the cascade configured to split the electromagnetic energy from the beamforming network input into two first-level beamforming waveguides,

a second level of the cascade configured to split the electromagnetic energy from each of two first-level beamforming waveguides into two respective second-level beamforming waveguides for each respective first-level beamforming waveguide, wherein one of two respective second-level beamforming waveguides for each respective first-level beamforming waveguide is coupled to one of the phase-adjustment sections, and

a third level of the cascade configured to split the electromagnetic energy from one of two respective second-level beamforming waveguides for each respective first-level beamforming waveguide into two respective third-level beamforming waveguides for each respective second-level beamforming waveguides, wherein each of the third-level beamforming waveguides is coupled to a respective one of the phase-adjustment sections.

2. The radar system according to claim 1, wherein the first level of the cascade is configured to divide power evenly between the two first-level beamforming waveguides.

3. The radar system according to claim 1, wherein each radiating waveguide of the six waveguides has a predetermined amplitude taper factor, and wherein the beamforming network is configured to provide an electromagnetic signal having an amplitude proportional to the associated amplitude taper factor of the respective radiating waveguide to the radiating waveguide input of the respective radiating waveguide.

4. The radar system according to claim 1, wherein the cascaded set of dividers comprises reactive elements.

5. The radar system according to claim 1, wherein the cascaded set of dividers comprises hybrids each having matched loads.

6. The radar system according to claim 1, wherein the beamforming waveguides each have a width equal to the width of the radiating waveguides.

7. The radar system according to claim 1, wherein each radiating waveguide of the six waveguides has a predetermined phase shift defined by a length of a corresponding phase-adjustment section.

8. The radar system according to claim 1, wherein each radiating element:

comprises a respective slot defined by a respective angular or curved path, and

has an effective length greater than the height of waveguide, wherein the effective length is measured along the respective angular or curved path of the respective slot.

9. The radar system according to claim 1, wherein the radiating element is configured to operate at approximately 77 Gigahertz (GHz) and propagate millimeter (mm) electromagnetic waves.

10. A method of radiating electromagnetic energy comprising:

receiving electromagnetic energy by a beamforming network input;

splitting the received electromagnetic energy with a cascaded set of dividers to form six electromagnetic energy streams coupled into six phase-adjustment sections, wherein the splitting comprises;

splitting the electromagnetic energy from the beamforming network input into two first-level beamforming waveguides by a first level of the cascade,

splitting the electromagnetic energy from each of two first-level beamforming waveguides into two respective second-level beamforming waveguides for each respective first-level beamforming waveguide by a second level of the cascade, wherein one of two respective second-level beamforming waveguides for each respective first-level beamforming waveguide is coupled to one of the phase-adjustment sections, and

splitting the electromagnetic energy from one of two respective second-level beamforming waveguides for each respective first-level beamforming waveguide into two respective third-level beamforming waveguides for each respective second-level beamforming waveguides by a third level of the cascade, wherein each of the third-level beamforming waveguides is coupled to a respective one of the phase-adjustment sections;

adjusting the phase of each of the six electromagnetic energy streams by the six phase-adjustment sections to form six phase adjusted electromagnetic energy streams;

coupling each of the six phase adjusted electromagnetic energy streams into a respective radiating waveguide of six radiating waveguides located in a waveguide layer, wherein each radiating waveguide is coupled to at least one radiating element located in a radiating layer; and

for each radiating waveguide, radiating at least a portion of the phase adjusted electromagnetic energy stream by a radiating element.

11. The method according to claim 10, further comprising dividing power evenly between the two first-level beamforming waveguides by the first level of the cascade.

12. The method according to claim 10, wherein each radiating waveguide of the six waveguides has an predetermined amplitude taper factor, and further comprising providing an electromagnetic signal having an amplitude proportional to the associated amplitude taper factor of the respective radiating waveguide to a radiating waveguide input of the respective radiating waveguide.

13. The method according to claim 10, wherein the cascaded set of dividers comprises reactive elements.

14. The method according to claim 10, wherein the cascaded set of dividers comprises hybrids each having matched loads.

15. The method according to claim 10, wherein the beamforming waveguides each have a width equal to the width of the radiating waveguides.

16. The method according to claim 10, wherein each radiating waveguide of the six waveguides has an predetermined phase shift defined by a length of a corresponding phase-adjustment section.

17. The method according to claim 10, wherein each radiating element:

comprises a respective slot defined by a respective angular or curved path, and

has an effective length greater than the height of waveguide, wherein the effective length is measured along the respective angular or curved path of the respective slot.

18. The method according to claim 10, wherein the electromagnetic energy has a frequency of approximately 77 Gigahertz (GHz).

19. A beamforming network located in a waveguide layer comprising:

a beamforming network input,

six beamforming network outputs, wherein each beamforming network output is coupled to a respective waveguide input of a set of waveguides,

a cascaded set of dividers coupled to six phase-adjustment sections, where the cascade is configured to distribute electromagnetic energy from the beamforming network input to the six phase-adjustment sections based on a predetermined taper profile, wherein the cascade comprises;

a first level of the cascade configured to approximately evenly split the electromagnetic energy from the beamforming network input into two first-level beamforming waveguides,

a second level of the cascade configured to split the electromagnetic energy from each of two first-level beamforming waveguides into two respective second-level beamforming waveguides for each respective first-level beamforming waveguide, wherein one of two respective second-level beamforming waveguides for each respective first-level beamforming waveguide is coupled to one of the phase-adjustment sections, and

a third level of the cascade configured to split the electromagnetic energy from one of two respective second-level beamforming waveguides for each respective first-level beamforming waveguide into two respective third-level beamforming waveguides for each respective second-level beamforming waveguides, wherein each of the third-level beamforming waveguides is coupled to a respective one of the phase-adjustment sections; and

wherein each phase-adjustment section has a respective length that provides a respective phase offset for each waveguide.

20. The beamforming network according to claim 19, wherein the beamforming network is configured to operate at approximately 77 Gigahertz (GHz).