Antenna and Radar System That Include a Polarization-Rotating Layer

• US 20180024226A1
• Filed: 07/21/2016
• Published: 01/25/2018
• Est. Priority Date: 07/21/2016
• Status: Active Grant

• Current Assignee: Waymo LLC (Alphabet Inc.)
• Original Assignee: Google Inc. (Alphabet Inc.)
• Inventors: Izadian, Jamal
• Granted Patent: US 10,539,656 B2
• Time in Patent Office: Days
• CPC Class Codes: G01S 7/024 using polarisation effects in waveguides H01P1/165; for aerials H01Q, e.g. H01Q15/22, H01Q15/24, H01Q19/195
• CPC Class Codes: G01S 7/03 Details of HF subsystems specially adapted therefor, e.g. common to transmitter and receiver
• CPC Class Codes: H01P 1/165 for rotating the plane of polarisation
• CPC Class Codes: H01P 5/12 Coupling devices having more than two ports H01P5/04 takes precedence
• CPC Class Codes: H01Q 1/3233 particular used as part of a sensor or in a security system, e.g. for automotive radar, navigation systems
• CPC Class Codes: H01Q 13/02 Waveguide horns
• CPC Class Codes: H01Q 13/0241 radiating a circularly polarised wave H01Q13/0258 takes precedence; polarisation converters H01Q15/244, in a waveguide H01P1/17
• CPC Class Codes: H01Q 15/246 rotating the plane of polarisation of a linear polarised wave guided wave H01P1/165
• CPC Class Codes: H01Q 21/0025 Modular arrays
• CPC Class Codes: H01Q 21/0037 linear waveguide fed arrays
• CPC Class Codes: H01Q 21/064 using horn or slot aerials slotted waveguides arrays H01Q21/005
• CPC Class Codes: H01Q 21/24 Combinations of antenna units polarised in different directions for transmitting or receiving circularly and elliptically polarised waves or waves linearly polarised in any direction circularly polarised patch antennas H01Q9/0428; circularly polarised horns H01Q13/0241; cross-polarised horns H01Q13/0258; polarisation converters H01Q15/242; cross-polarised rear feeds H01Q19/136; crossed polarisation dual antenna H01Q25/001
• CPC Class Codes: H01Q 5/55 for horn or waveguide antennas

Abstract

An antenna includes a plurality of waveguide antenna elements arranged in a first array configured to operate with a first polarization. The antenna also includes a plurality of waveguide output ports arranged in a second array configured to operate with a second polarization. The second polarization is different from the first polarization. The antenna further includes a polarization-rotating layer with channels defined therein. The polarization-rotating layer is disposed between the waveguide antenna elements and the waveguide output ports. The channels are oriented at a first angle with respect to the waveguide antenna elements and at a second angle with respect to the waveguide output ports. The channels are configured to receive input electromagnetic waves having the first polarization and transmit output electromagnetic waves having a first intermediate polarization. The waveguide output ports are configured to receive input electromagnetic waves and radiate electromagnetic waves having the second polarization.

Claims

1. An antenna, comprising:

a plurality of waveguide antenna elements arranged in a first array configured to operate with a first polarization;

a plurality of waveguide output ports arranged in a second array configured to operate with a second polarization, wherein the second polarization is different from the first polarization; and

a polarization-rotating layer with channels defined therein,

wherein the polarization-rotating layer is disposed between the waveguide antenna elements and the waveguide output ports,

wherein the channels are oriented at a first angle with respect to the waveguide antenna elements and at a second angle with respect to the waveguide output ports,

wherein the channels are configured to receive input electromagnetic waves having the first polarization and transmit output electromagnetic waves having a first intermediate polarization, and

wherein the waveguide output ports are configured to receive input electromagnetic waves and radiate electromagnetic waves having the second polarization.

2. The antenna of claim 1, wherein the waveguide antenna elements and the waveguide output ports are substantially rectangular in shape.

3. The antenna of claim 1, wherein the waveguide antenna elements and the waveguide output ports are substantially circular in shape.

4. The antenna of claim 1, wherein the channels are shaped as rounded rectangles.

5. The antenna of claim 1, wherein the first polarization is orthogonal to the second polarization.

6. The antenna of claim 1, wherein the first angle is between 44 and 46 degrees and wherein the second angle is between 44 and 46 degrees.

7. The antenna of claim 1, wherein a thickness of the polarization-rotating layer is between a half and a whole wavelength of the input electromagnetic waves having the first polarization.

8. The antenna of claim 1, wherein the channels are filled with a dielectric material.

9. The antenna of claim 1, further comprising a secondary polarization-rotating layer with secondary channels defined therein,

wherein the secondary polarization-rotating layer is disposed between the polarization-rotating layer and the waveguide output ports,

wherein the secondary channels are oriented at a third angle with respect to the waveguide antenna elements and at a fourth angle with respect to the waveguide output ports,

wherein the secondary channels are configured to receive input electromagnetic waves having the first intermediate polarization and transmit output electromagnetic waves having a second intermediate polarization, and

wherein the first intermediate polarization is different from the second intermediate polarization.

10. The antenna of claim 9, wherein a bandwidth of usable frequencies associated with the radar antenna lies within the 77 GHz band.

11. The antenna of claim 9, wherein the first angle is between 25 and 35 degrees, wherein the second angle is between 50 and 70 degrees, wherein the third angle is between 50 and 70 degrees, and wherein the fourth angle is between 25 and 35 degrees.

12. A radar system, comprising:

a transmitter, comprising;

a plurality of first waveguide antenna elements arranged in a first array configured to operate with a first polarization;

a first polarization-rotating layer with first channels defined therein,

wherein the first polarization-rotating layer is disposed adjacent to the first waveguide antenna elements,

wherein the first channels are oriented at a first angle with respect to the first waveguide antenna elements, and

wherein the first channels are configured to receive input electromagnetic waves having the first polarization and transmit output electromagnetic waves having a second polarization; and

a receiver, comprising;

a plurality of second waveguide antenna elements arranged in a second array configured to operate with the first polarization;

a second polarization-rotating layer with second channels defined therein,

wherein the second polarization-rotating layer is disposed adjacent to the second waveguide antenna elements,

wherein the second channels are oriented at the first angle with respect to the second waveguide antenna elements, and

wherein the second channels are configured to receive input electromagnetic waves having the second polarization and transmit output electromagnetic waves having the first polarization to the second waveguide antenna elements.

13. The radar system of claim 12,

wherein the transmitter further comprises:

a third polarization-rotating layer with third channels defined therein,

wherein the third polarization-rotating layer is disposed adjacent to the first polarization-rotating layer,

wherein the third channels are oriented at a second angle with respect to the first channels, and

wherein the third channels are configured to receive input electromagnetic waves having the second polarization and transmit output electromagnetic waves having a third polarization; and

wherein the receiver further comprises;

a fourth polarization-rotating layer with fourth channels defined therein,

wherein the fourth polarization-rotating layer is disposed adjacent to the second polarization-rotating layer,

wherein the fourth channels are oriented at the second angle with respect to the second channels, and

wherein the fourth channels are configured to receive input electromagnetic waves having the third polarization and transmit output electromagnetic waves having the second polarization to the second channels.

14. The radar system of claim 13, wherein the first angle is between 20 and 25 degrees, and wherein the second angle is between 20 and 25 degrees.

15. The radar system of claim 12, wherein the radar system is configured to be used by an autonomous vehicle for navigation.

16. The radar system of claim 12, wherein the first channels and the second channels are shaped as rounded rectangles.

17. The radar system of claim 12, wherein the first angle is between 44 and 46 degrees.

18. The radar system of claim 12, wherein a thickness of the first polarization-rotating layer is less than a wavelength of the input electromagnetic waves having the first polarization.

19. The radar system of claim 12, wherein the first channels and the second channels are filled with a dielectric material.

20. A method, comprising:

emitting electromagnetic waves having a first polarization from a plurality of waveguide antenna elements arranged in a first array;

receiving, by channels defined within a polarization-rotating layer that is disposed between the waveguide antenna elements and a plurality of waveguide output ports arranged in a second array, the electromagnetic waves having the first polarization, wherein the channels are oriented at a first angle with respect to the waveguide antenna elements;

transmitting, by the channels defined within the polarization-rotating layer, electromagnetic waves having an intermediate polarization;

receiving, by the waveguide output ports, electromagnetic waves having the intermediate polarization, wherein the waveguide output ports are oriented at a second angle with respect to the channels; and

radiating, by the waveguide output ports, electromagnetic waves having a second polarization, wherein the second polarization is different from the first polarization, wherein the second polarization is different from the intermediate polarization, and wherein the first polarization is different from the intermediate polarization.